Micro movable device and optical switching apparatus

A micro movable device includes: a micro movable substrate including a micro movable unit, the micro movable unit including a frame section, a movable section, and a coupling section which couples the frame section and the movable section to each other; a support base; a first spacer and a second spacer which are provided between the frame section of the micro movable substrate and the base, the first and second spacers joining the frame section and the base to each other; and a fixation member provided between the frame section of the micro movable substrate and the base, the fixation member including a spacer portion which joins the frame section and the base to each other and an adhesive portion which covers the spacer portion and joins the frame section and the base to each other, the fixation member being provided between the first and second spacers.

CROSS-REFERENCE TO RELATED APPLICATION

This application is based upon and claims the benefit of priority of the prior Japanese Patent Application No. 2008-261653, filed on Oct. 8, 2008, the entire contents of which are incorporated herein by reference.

FIELD

The embodiments discussed herein are related to a micro movable device including a small movable section, and to an optical switching apparatus including a micromirror device.

BACKGROUND

Recently, devices having a microstructure formed by micromachining techniques have been used in various fields. Examples of such devices include micro movable devices, such as a micromirror device, an angular velocity sensor, and an acceleration sensor, which include small movable sections. The micromirror device is used as, for example, an optical reflective device in the field of optical communication and optical disc technology. The angular velocity sensor and the acceleration sensor are used in, for example, a image stabilizing devices in video cameras or camera-equipped mobile phones, car navigation systems, airbag-deployment timing systems, or position control systems for vehicles or robots. Japanese Unexamined Patent Application Publications Nos. 2003-19700, 2004-341364, and 2006-72252 disclose examples of micro movable devices.

SUMMARY

According to an aspect of an invention, a micro movable device includes: a micro movable substrate including a micro movable unit, the micro movable unit including a frame section, a movable section, and a coupling section which couples the frame section and the movable section to each other; a support base; a first spacer and a second spacer which are provided between the frame section of the micro movable substrate and the support base, the first spacer and the second spacer joining the frame section and the support base to each other; and a fixation member provided between the frame section of the micro movable substrate and the support base, the fixation member including a spacer portion which joins the frame section and the support base to each other and an adhesive portion which covers the spacer portion and joins the frame section and the support base to each other, the fixation member being provided between the first spacer and the second spacer.

DESCRIPTION OF EMBODIMENTS

FIGS. 1 to 11illustrate a micro movable device X1according to a first embodiment.FIG. 1is a plan view of the micro movable device X1.FIG. 2is a plan view of a part of the micro movable device X1.FIG. 3is a plan view of another part of the micro movable device X1.FIGS. 4 to 8are sectional views ofFIG. 1taken along lines IV-IV, V-V, VI-VI, VII-VII, and VIII-VIII, respectively.FIGS. 9 to 11are sectional views ofFIG. 1taken along lines IX-IX, X-X, and XI-XI, respectively.

The micro movable device X1includes a micro movable substrate S1, a wiring board S2, spacers90A and90B, and reinforced fixation members90C. According to the present embodiment, the micro movable device X1may be used as a micromirror device.

As illustrated inFIG. 1, the micro movable substrate S1includes a micro movable unit Xa. The micro movable unit Xa includes an oscillating portion10, frames20and30, a pair of connecting portions41, a pair of connecting portions42and43, and electrode portions50,60, and70. The micro movable unit Xa is obtained by subjecting a material substrate to processes using bulk micromachining technology, such as micro-electromechanical systems (MEMS) technology. A silicon-on-insulator (SOI) wafer, for example, may be used as the material substrate. The material substrate has a layered structure including a first silicon layer, a second silicon layer, and an insulating layer interposed between the first and second silicon layers. The first and second silicon layers are doped with impurities which apply conductivities to the first and second silicon layers. Each of the above-mentioned portions of the micro movable unit Xa is formed in the first silicon layer or the second silicon layer. To facilitate understanding of the drawings, portions formed in the first silicon layer are shaded inFIG. 1. InFIG. 2, portions of the micro movable unit Xa formed in the second silicon layer are illustrated as provided on the wiring board S2. In other words, inFIG. 2, portions formed in the first silicon layer, portions formed on the first silicon layer, and portions formed in the insulating layer in the micro movable substrate S1are omitted.

The oscillating portion10of the micro movable unit Xa includes a land portion11, an electrode portion12, and a beam portion13.

The land portion11is formed in the first silicon layer. The land portion11has a mirror surface11ahaving a light-reflecting function on a surface thereof. The land portion11and the mirror surface11afunction as a movable body of the micro movable unit Xa. A length W (seeFIG. 1) of the movable body or the land portion11may be, for example, 20 μm to 300 μm.

The electrode portion12is also formed in the first silicon layer. The electrode portion12includes two arms and a plurality of electrode fingers which extend from the arms. Thus, the electrode portion12has a comb-electrode structure. When the micro movable device X1or the micro movable unit Xa is driven, a reference potential (for example, a ground potential) is supplied to the electrode portion12.

The beam portion13is also formed in the first silicon layer. The beam portion13connects the land portion11and the electrode portion12to each other.

As illustrated inFIGS. 4 to 6, the frame20includes a first layer21formed in the first silicon layer, a second layer22formed in the second silicon layer, and an insulating layer23interposed between the first and second layers21and22. Thus, the frame20has a layered structure. As illustrated inFIG. 1, the first layer21includes portions21a,21b, and21cwhich are separated from each other. As illustrated inFIG. 2, the second layer22includes portions22aand22bwhich are separated from each other. As illustrated inFIG. 1, the portion21aof the first layer21is shaped so as to partially surround the oscillating portion10. The portion22aof the second layer22is a frame body which is shaped so as to partially surround the oscillating portion10. As illustrated inFIG. 6, the portions21aand22aare electrically connected to each other by conductive vias24awhich extend through the insulating layer23. The portions21band22bare electrically connected to each other by a conductive via24bwhich extends through the insulating layer23. As illustrated inFIG. 7, the portions21cand22aare electrically connected to each other by a conductive via24cwhich extends through the insulating layer23.

As illustrated inFIGS. 9 to 11, the frame30includes a first layer31formed in the first silicon layer, a second layer32formed in the second silicon layer, and an insulating layer33interposed between the first and second layers31and32. As illustrated inFIG. 1, the first layer31includes portions31aand31bwhich are separated from each other. As illustrated inFIG. 2, the second layer32includes portions32a,32b,32c, and32dwhich are separated from each other. As illustrated inFIG. 9, the portions31band32bare electrically connected to each other by a conductive via34awhich extends through the insulating layer33. As illustrated inFIG. 11, each of the portions32dis electrically connected to the portion31aby a conductive via34bwhich extends through the insulating layer33. In addition, as illustrated inFIGS. 9 to 11, pads35are provided on the surfaces of the portions32ato32d.

Each of the connecting portions41is a torsion bar. The connecting portions41are formed in the first silicon layer. The connecting portions41connect the beam portion13of the oscillating portion10to the portion21aof the first layer21of the frame20. Thus, the oscillating portion10and the frame20are connected to each other. The beam portion13and the portion21aare electrically connected to each other by the connecting portions41. As illustrated inFIG. 4, the dimension of the connecting portions41in the thickness direction H is smaller than that of the oscillating portion10, and is also smaller than that of the first layer21of the frame20. The connecting portions41define an axial center A1of rotation of the oscillating portion10or the movable body (the land portion11and the mirror surface11a). The direction in which the electrode fingers in the electrode portion12extend is parallel to the direction of the axial center A1.

Each of the connecting portions42and43is a torsion bar. The connecting portions42and43are formed in the first silicon layer. The connecting portions42and43connect the frame20and the frame30to each other. As illustrated inFIG. 1, the connecting portion42is connected to the portion21bof the first layer21of the frame20and the portion31bof the first layer31of the frame30. Accordingly, the frame20and the frame30are connected to each other. The portions21band31bare electrically connected to each other by the connecting portion42. The connecting portion43is connected to the portion21cof the first layer21of the frame20and the portion31aof the first layer31of the frame30. Accordingly, the frame20and the frame30are connected to each other. The portions21cand31aare electrically connected to each other by the connecting portion43. The dimensions of the connecting portions42and43in the thickness direction H are smaller than that of the first layer21of the frame20, and are also smaller than that of the first layer31of the frame30. The connecting portions42and43define an axial center A2of rotation of the frame20and the oscillating portion10. In the present embodiment, the axial center A2is perpendicular to the axial center A1.

The electrode portion50is formed in the second silicon layer. As illustrated inFIG. 2, the electrode portion50includes an arm and a plurality of electrode fingers which extend from the arm. Thus, the electrode portion50has a comb-electrode structure. The electrode portion50extends from the portion22bof the second layer22of the frame20.

The electrode portion60is formed in the first silicon layer. As illustrated inFIGS. 1 and 8, the electrode portion60includes a plurality of electrode fingers which extend in a direction toward the electrode portion70from the portion21cof the first layer21of the frame20. Thus, the electrode portion60has a comb-electrode structure.

The electrode portion70is formed in the second silicon layer. As illustrated inFIG. 2, the electrode portion70includes an arm and a plurality of electrode fingers which extend from the arm in a direction toward the electrode portion60. Thus, the electrode portion70has a comb-electrode structure. The electrode portion70extends from the portion32cof the second layer32of the frame30.

In the micro movable substrate S1or the micro movable unit Xa, the pair of electrode portions12and50function as a part of a driving mechanism or an actuator for generating a driving force for rotating the oscillating portion10around the axial center A1. The pair of electrode portions60and70function as a part of a driving mechanism or an actuator for generating a driving force for rotating the frame20and the oscillating portion10around the axial center A2. In the micro movable substrate S1or the micro movable unit Xa, the oscillating portion10, the frame20, the connecting portions41, and the electrode portions50and60form a movable section.

As illustrated inFIG. 3, the wiring board S2of the micro movable device X1includes a base81, wiring patterns82A,82B, and82C, and pads83. The base81is made of a silicon material. Each of the wiring patterns82A,82B, and82C includes pads82aand82b. The pads82aserve as external connection terminals of the micro movable device X1.

As illustrated inFIGS. 9 to 11, each of the spacers90A includes a bump unit91A and an adhesive portion92. The spacers90A are disposed between the micro movable substrate S1and the wiring board S2or between the frame30of the micro movable unit Xa and the wiring board S2. In the present embodiment, each of the bump units91A includes two bumps placed on top of each other. The bumps may be made of, for example, Au. The bump units91A are pressed against the pads82bin the wiring patterns82A,82B, and82C on the wiring board S2. In addition, the bump units91A are joined to the pads35on the frame30in the micro movable substrate S1via the adhesive portions92. The adhesive portions92are made of a conductive adhesive containing conductive fillers. The conductive adhesive may be obtained by mixing silver filler into an epoxy adhesive which serves as a main component. A material having a high resistance to ambient temperature is preferably used as the epoxy resin material. In the present embodiment, the spacers90A having the above-described structure electrically connect the micro movable substrate S1and the wiring board S2to each other.

As illustrated inFIGS. 9 to 11, each of the spacers90B includes a bump unit91B and an adhesive portion92. The spacers90B are disposed between the frame30in the micro movable substrate S1and the wiring board S2. In the present embodiment, each of the bump units91B includes two bumps placed on top of each other. The bumps may be made of, for example, Au. The bump units91B are pressed against the pads83on the wiring board S2. In addition, the bump units91B are joined to the pads35on the frame30in the micro movable substrate S1by the adhesive portions92. The adhesive portions92may be made of, for example, conductive adhesive.

As illustrated inFIGS. 9 to 11, each of the reinforced fixation members90C includes a bump unit91C and adhesive portions92and93. The reinforced fixation members90C are disposed between the frame30in the micro movable substrate S1and the wiring board S2. In the present embodiment, each of the bump units91C includes two bumps placed on top of each other. The bumps may be made of, for example, Au. The bump units91C are pressed against the pads83on the wiring board S2. In addition, the bump units91C are joined to the pads35on the frame30in the micro movable substrate S1by the adhesive portions92. The adhesive portions92may be made of, for example, a conductive adhesive. In the reinforced fixation members90C, the bump units91C serve as spacer portions. The adhesive portions93are made of reinforcing adhesive. The adhesive portions93are provided so as to cover the periphery of the bump units91C. The adhesive portions93are joined to the micro movable substrate S1and the wiring board S2. The reinforcing adhesive may be, for example, an epoxy resin. A material having a high resistance to ambient temperature or a material having bridging silicone particles mixed therein is preferably used as the epoxy resin material. Since the reinforced fixation members90C are provided, the micro movable substrate S1and the wiring board S2may be more strongly fixed to each other compared to only providing the spacers90A and90B.

As illustrated inFIGS. 9 to 11, each of the reinforced fixation members90C is disposed between the corresponding pair of spacers90A and90B. The pairs of spacers90A and90B and the reinforced fixation members90C illustrated inFIGS. 9 to 11are arranged in a line parallel to the axial center A2of the micro movable unit Xa, as illustrated inFIG. 2. The pair of spacers90A and90B and the reinforced fixation member90C illustrated inFIG. 9are joined to the frame30at positions along the axial center A2. The pair of spacers90A and90B and the reinforced fixation member90C illustrated inFIG. 10are also joined to the frame30at positions along the axial center A2. The axial center A2is a center of rotation of the movable section (the oscillating portion10, the frame20, the connecting portions41, the electrode portion50, and the electrode portion60) with respect to a fixed section or the frame30, and is defined by the connecting portions42and43.

When the micro movable device X1is driven, the reference potential is applied to the electrode portion12of the oscillating portion10and the electrode portion60. The reference potential is applied to the electrode portion12through the wiring patterns82C (including the pads82awhich serve as external connection terminals) on the wiring board S2, the spacers90A on the pads82bof the wiring patterns82C, the pads35provided on the micro movable substrate S1and joined to the spacers90A, the portions32dof the second layer32of the frame30in the micro movable substrate S1, the conductive vias34b, the portion31aof the first layer31, the connecting portion43, the portion21cof the first layer21of the frame20, the conductive via24c, the portion22aof the second layer22, the conductive vias24a, the portion21aof the first layer21, the connecting portions41, and the beam portion13of the oscillating portion10. The reference potential is applied to the electrode portion60through the wiring patterns82C (including the pads82awhich serve as external connection terminals) on the wiring board S2, the spacers90A on the pads82bof the wiring patterns82C, the pads35provided on the micro movable substrate S1and joined to the spacers90A, the portions32dof the second layer32of the frame30in the micro movable substrate S1, the conductive vias34b, the portion31aof the first layer31, the connecting portion43, and the portion21cof the first layer21of the frame20. The reference potential may be, for example, a ground potential and is preferably maintained constant.

In this state, a drive potential, which is higher than the reference potential, is applied to each of the electrode portions50and70if necessary. When an electrostatic attractive force is generated between the electrode portions12and50, the oscillating portion10rotates around the axial center A1, as illustrated inFIG. 12. When an electrostatic attractive force is generated between the electrode portions60and70, the frame20and the oscillating portion10rotate around the axial center A2. Thus, the micro movable device X1functions as a two-axis movable device. The drive potential is applied to the electrode portion50through the wiring pattern82A (including the pad82awhich serves as an external connection terminal) on the wiring board S2, the spacer90A on the pad82bof the wiring pattern82A, the pad35provided on the micro movable substrate S1and joined to the spacer90A, the portion32bof the second layer32of the frame30in the micro movable substrate S1, the conductive via34a, the portion31bof the first layer31, the connecting portion42, the portion21bof the first layer21of the frame20, the conductive via24b, and the portion22bof the second layer22. The drive potential is applied to the electrode portion70through the wiring pattern82B (including the pad82awhich serves as an external connection terminal) on the wiring board S2, the spacer90A on the pad82bof the wiring pattern82B, the pad35provided on the micro movable substrate S1and joined to the spacer90A, and the portion32cof the second layer32of the frame30in the micro movable substrate S1. Due to the above-described rotation around the two axes, the direction in which light is reflected by the mirror surface11aprovided on the land portion11of the micro movable unit Xa included in the micro movable device X1may be changed.

The micro movable device X1may also be used as a sensing device, such as an angular velocity sensor or an acceleration sensor. When the micro movable device X1is used as a micro sensing device, it is not necessary to provide the mirror surface11aon the land portion11of the oscillating portion10in the micro movable unit Xa.

When the micro movable device X1is used as an angular velocity sensor, the movable section (the oscillating portion10, the frame20, the connecting portions41, the electrode portion50, and the electrode portion60) may be rotated, for example, around the axial center A2at a specific frequency or period. The movable section may be rotated by applying a voltage between the electrode portions60and70at a specific period. In the present embodiment, for example, the electrode portion60is connected to the ground potential while a potential is applied to the electrode portion70at a specific period.

If an angular velocity is applied to the micro movable device X1or the oscillating portion10while the movable section is being vibrated in the above-described manner, the oscillating portion10rotates around the axial center A1. Thus, the positional relationship between the electrode portions12and50changes and the capacitance between the electrode portions12and50changes accordingly. The amount of rotation of the oscillating portion10may be detected based on the change in the capacitance. The angular velocity applied to the micro movable device X1or the oscillating portion10may be calculated based on the detection result of the amount of rotation.

When the micro movable device X1is used as an acceleration sensor, a direct-current voltage is applied between the electrode portions12and50. Thus, the oscillating portion10is put into a stationary state with respect to the frame20and the electrode portion50. In this state, if an acceleration is applied to the micro movable device X1or the oscillating portion10in the direction of a normal line (in a direction perpendicular to the plan view illustrated inFIG. 1), an inertial force having a vector component parallel to the acceleration is generated. Accordingly, a rotational torque around the axial center A1is applied to the oscillating portion10. As a result, the oscillating portion10rotates around the axial center A1such that the rotational displacement of the oscillating portion10is proportional to the acceleration. Referring to the plan view illustrated inFIG. 1, the above-mentioned inertial force may be generated when the structure is designed such that the center of gravity of the oscillating portion10does not coincide with the axial center A1. The rotational displacement is electrically detected based on a change in the capacitance between the electrode portions12and50. The acceleration applied to the micro movable device X1or the oscillating portion10may be calculated based on the result of detection of the capacitance.

FIGS. 13A to 16Billustrate an example of a method for manufacturing the micro movable device X1.FIGS. 13A to 14Dillustrate an example of a method for manufacturing the micro movable substrate S1included in the micro movable device X1. This method is one of methods for forming the micro movable unit Xa using bulk micromachining technology. The sectional views illustrated inFIGS. 13A to 14Dillustrate the processing for forming a land portion L, a beam portion B, frames F1, F2, and F3, connecting portions C1and C2, and a pair of electrodes E1and E2illustrated inFIG. 14D. The land portion L corresponds to a part of the land portion11. The beam portion B corresponds to the beam portion13. The frame F1corresponds to a part of the frame20. The frames F2and F3correspond to parts of the frame30. The connecting portion C1corresponds to the connecting portions41. The connecting portion C2corresponds to each of the connecting portions41,42, and43. The electrode E1corresponds to a part of each of the electrode portions12and60. The electrode E2corresponds to a part of each of the electrode portions50and70.FIGS. 15A to 15Cillustrate processing for processing the wiring board S2.FIGS. 16A and 16Billustrate a processing of joining the micro movable substrate S1and wiring board S2to each other (substrate bonding processing).

In the process of forming the micro movable unit Xa, first, a material substrate100is prepared, as illustrated inFIG. 13A. The material substrate100includes silicon layers101and102and an insulating layer103interposed between the silicon layers101and102. An SOI wafer, for example, having a layered structure may be used as the material substrate100. Conductive vias, which serve as the above-described conductive vias24ato24c,34a, and34b, are formed in the insulating layer103of the material substrate100in advance. The silicon layers101and102are doped with impurities to apply conductivity thereto. The impurities may be p-type impurities, such as B, or n-type impurities, such as P and Sb. The insulating layer103may be made of, for example, silicon oxide. The thickness of the silicon layer101may be, for example, 10 μm to 100 μm. The thickness of the silicon layer102may be, for example, 50 μm to 500 μm. The thickness of the insulating layer103may be, for example, 0.3 μm to 3 μm.

As illustrated inFIG. 13B, the mirror surface11ais formed on the silicon layer101. In addition, the pads35are formed on the silicon layer102. In the process of forming the mirror surface11a, first, a metal film, such as a Cr film, is formed on the silicon layer101by sputtering. Then, another metal film, such as an Au film, is formed on the Cr film. The thickness of the Cr film may be, for example, 50 nm. The thickness of the Au film may be, for example, 200 nm. Then, the metal films are formed into a certain pattern by etching using a mask. Thus, the mirror surface11ais formed. A solution of potassium iodide and iodine, for example, may be used as an etchant for Au. A solution of di-ammonium cerium (IV) nitrate, for example, may be used as an etchant for Cr. The pads35are formed on the silicon layer102by a process similar to for the process for forming the mirror surface11a.

As illustrated inFIG. 13C, an oxide film pattern110and a resist pattern111are formed on the silicon layer101. In addition, an oxide film pattern112is formed on the silicon layer102. The oxide film pattern110has a shape corresponding to the oscillating portion10(the land portion11, the electrode portion12, and the beam portion13), the first layer21of the frame20, the first layer31of the frame30, and the electrode portion60, all of which are to be formed in the silicon layer101. The shape of the oxide film pattern110is illustrated inFIG. 17. The resist pattern111has a shape corresponding to the connecting portions41to43. The oxide film pattern112has a shape corresponding to the second layer22of the frame20, the second layer32of the frame30, and the electrode portions50and70, all of which are to be formed in the silicon layer102. The shape of the oxide film pattern112is illustrated inFIG. 18.

As illustrated inFIG. 13D, the silicon layer101is etched to a specific depth by deep reactive ion etching (DRIE) using the oxide film pattern110and the resist pattern111as masks. The specific depth is a depth corresponding to the thickness of the connecting portions C1and C2, and is set to, for example, 5 μm. In the DRIE, the Bosch process may be used. The Bosch process is a process in which etching using SF6 gas and side wall protection using C4F8 gas are alternately performed. If the Bosch process is used, satisfactory anisotropic etching may be achieved. The Bosch process may also be used in the DRIE described below.

As illustrated inFIG. 14A, the resist pattern111is removed. The resist pattern111may be removed by, for example, exposing the resist pattern111to a releasing agent.

As illustrated inFIG. 14B, the silicon layer101is etched down to the insulating layer103by DRIE using the oxide film pattern110as a mask. The etching is performed such that the connecting portions C1and C2remain. As a result, the land portion L, the beam portion B, the electrode E1, a part of the frame F1(the first layer21of the frame20), a part of the frame F2(the first layer31of the frame30), a part of the frame F3(the first layer31of the frame30), and the connecting portions C1and C2are formed.

As illustrated inFIG. 14C, the silicon layer102is etched down to the insulating layer103by DRIE using the oxide film pattern112as a mask. As a result, another part of the frame F1(the second layer22of the frame20), another part of the frame F2(the second layer32of the frame30), another part of the frame F3(the second layer32of the frame30), and the electrode E2are formed.

As illustrated inFIG. 14D, exposed portions of the insulating layer103and the oxide film patterns110and112are etched away. As an etching method, either dry etching or wet etching may be used. When dry etching is used, CF4, CHF3, etc., may be used as an etching gas. When wet etching is used, buffered hydrogen fluoride (BHF) including fluorinated acid and ammonium fluoride may be used as an etchant. After this processing, the material substrate100is cut so as to separate micro movable units Xa from each other.

By performing the above-described procedure, the micro movable substrate S1including the micro movable unit Xa is manufactured.

In the process of manufacturing the micro movable device X1, as illustrated inFIG. 15A, the bump units91A,91B, and91C are formed on the wiring board S2. The wiring patterns82A,82B, and82C including the pads82aand82band the pads83are formed in advance on the surface of the wiring board S2. In this way, two bumps are stacked on each of the pads82band83using a bump bonder. Thus, a plurality of double-bump structures are formed. The pads and the bumps are pressure-bonded to one another. Next, a leveling processing is performed to make the heights of the double-bump structures uniform. Thus, the bump units91A to91C are formed. The leveling processing may be performed by, for example, pressing a flat surface of a glass plate or the like against top portions of the double-bump structures.

As illustrated inFIG. 15B, thermosetting conductive adhesive92′ is applied to the top portions of the bump units91A to91C. For example, the bump units91A to91C on the wiring board S2are brought into contact with a flat substrate on which the conductive adhesive92′ is applied at a uniform thickness (for example, 25 μm). The conductive adhesive92′ may be transferred onto the top portions of the bump units91A to91C by using the above-described method.

As illustrated inFIG. 15C, thermosetting reinforcing adhesive93′ is applied to the bump units91C. For example, the reinforcing adhesive93′ is applied to the bump units91C with a dispenser such that the bump units91C are covered by the reinforcing adhesive93′. The amount of reinforcing adhesive93′ provided so as to cover each of the bump units91C may be larger than the amount of conductive adhesive92′ applied only to the top portion of each of the bump units91A to91C.

After the reinforcing adhesive93′ is applied, as illustrated inFIGS. 16A and 16B, the micro movable substrate S1and the wiring board S2are joined to each other such that the bump units91A to91C, the conductive adhesive92′, and the reinforcing adhesive93′ are disposed therebetween. In this processing, the conductive adhesive92′ and the reinforcing adhesive93′ are cured by applying heat, so that the adhesive portions92and93are formed.

Thus, the micro movable device X1is manufactured which includes the micro movable substrate S1, the wiring board S2, and the spacers90A and90B and the reinforced fixation members90C which are disposed between the micro movable substrate S1and the wiring board S2to join them together.

In the process of joining the micro movable substrate S1and the wiring board S2to each other, the adhesive portions93of the reinforced fixation members90C are formed by curing a large amount of reinforcing adhesive93′ applied to the bump units91C. The reinforcing adhesive93′ contracts when it is cured. Therefore, a stress is applied to the frame30in the micro movable substrate S1at positions where the reinforced fixation members90C are joined. For example, a tensile stress is applied in a direction such that the distance between the micro movable substrate S1and the wiring board S2decreases. However, as illustrated inFIGS. 9 to 11, each of the reinforced fixation members90C including the adhesive portions93is disposed between the corresponding pair of spacers90A and90B. Therefore, in the micro movable device X1, the frame30may be prevented from being deformed by the above-described stress. The spacers90A and90B and the reinforced fixation members90C disposed therebetween resist the stress applied to the frame30at positions where the reinforced fixation members90C are joined. Therefore, the boundary between the adhesive portion93of each reinforced fixation member90C and the micro movable substrate S1serves as a power point and the boundary between each of the spacers90A and90B and the micro movable substrate S1serves as a fulcrum, so that deformation of the frame30is prevented. As a result, in the micro movable device X1, spring constants of the connecting portions42and43after the processing of joining the micro movable substrate S1and the wiring board S2to each other may be prevented from being changed due to the joining. Changes in the spring constants of the connecting portions42and43, which are connected to the frame30, may be caused by the deformation of the frame30.

In addition, in the manufactured micro movable device X1, the volume of the adhesive portion93of each reinforced fixation member90C varies in accordance with the temperature variation. Therefore, a stress is applied to the frame30in the micro movable substrate S1at positions where the reinforced fixation members90C are joined. However, as illustrated inFIGS. 9 to 11, each of the reinforced fixation members90C including the adhesive portions93is disposed between the corresponding pair of spacers90A and90B with which the micro movable substrate S1and the wiring board S2are joined to each other. Therefore, in the micro movable device X1, the frame30may be prevented from being deformed by the above-described stress. The spacers90A and90B and the reinforced fixation members90C resist the stress applied to the frame30at positions where the reinforced fixation members90C are joined. Therefore, the boundary between the adhesive portion93of each reinforced fixation member90C and the micro movable substrate S1serves as a point of force and the boundary between each of the spacers90A and90B and the micro movable substrate S1serves as a fulcrum, so that deformation of the frame30may be prevented. As a result, in the micro movable device X1, spring constants of the connecting portions42and43after the processing of joining the micro movable substrate S1and the wiring board S2to each other may be prevented from being changed due to the joining.

As described above, the spring constants of the connecting portions42and43, which connect the movable section (the oscillating portion10, the frame20, the connecting portions41, the electrode portion50, and the electrode portion60) to the frame30, may be prevented from being changed during the manufacturing process of the micro movable device X1or after the manufacturing process of the micro movable device X1. In this type of micro movable device X1, variations in mechanical characteristics, such as the resonance frequency of the movable section, may be adequately suppressed. Therefore, degradation of performance of the device may be suppressed.

In the micro movable device X1, the base material of the micro movable substrate S1is a silicon material, as described above. The base81, which is the base material of the wiring board S2, is also made of a silicon material, as described above. Therefore, a difference between a change in the volume of the micro movable substrate S1and a change in the volume of the wiring board S2(support base) due to temperature variation may be reduced. As a result, a stress applied to the frame30in the micro movable substrate S1at positions where the reinforced fixation members90C are joined may be reduced.

FIGS. 19A and 19Billustrate a modification of the reinforced fixation members90C.FIG. 19Ais a sectional view of a reinforced fixation member90C according to the modification taken along a thickness direction of the wiring board S2.FIG. 19Bis a sectional view of the reinforced fixation member90C according to the modification taken along a direction in which the wiring board S2extends. Referring toFIGS. 19A and 19B, the reinforced fixation member90C includes a plurality of bump units91C. Each of the bump units91C includes two bumps, such as Au bumps, which are placed on top of each other. The bump units91C are pressed against a single pad83provided on the wiring board S2. In addition, the bump units91C are joined to a corresponding pad35provided on the frame30in the micro movable substrate S1by respective adhesive portions92. The adhesive portions92are made of a conductive adhesive. The conductive adhesive contains conductive filler. The adhesive portion93is made of a reinforcing adhesive. The adhesive portion93is provided so as to cover the periphery of the bump units91C and join the micro movable substrate S1and the wiring board S2to each other. In this structure, the volume ratio of the adhesive portion93is smaller than that in the case where a single bump unit91C is included in the reinforced fixation member90C. Therefore, in the process of curing the reinforcing adhesive93′, a frictional force is effectively generated at the boundary between the reinforcing adhesive93′, which contracts in the curing process, and the bump units91C. As a result, the contraction of the reinforcing adhesive93′ is suppressed. The above-mentioned frictional force is applied so as to resist the contraction of the reinforcing adhesive93′. Therefore, as illustrated inFIGS. 19A and 19B, the reinforced fixation member90C including the plurality of bump units91C contributes to suppressing the variation in the spring constants of the connecting portions42and43.

In the micro movable device X1, the pairs of spacers90A and90B and the strong fixation portions90C illustrated inFIGS. 9 to 11are arranged in a line parallel to the axial center A2of the micro movable unit Xa. In addition, the pair of spacers90A and90B and the reinforced fixation portion90C illustrated inFIG. 9are joined to the frame30at positions on the axial center A2. The pair of spacers90A and90B and the strong fixation portion90C illustrated inFIG. 10are also joined to the frame30at positions on the axial center A2.

The shape of the pattern of the portions32ato32dof the second layer32of the frame30in the micro movable substrate S1, the shape of the wiring patterns82A to82C and the pattern of the pads83on the wiring board S2, and the arrangement of each set of the spacers90A and90B and the reinforced fixation member90C, which are arranged in a single row, may be changed such that the micro movable substrate S1and the wiring board S2are electrically connected to each other by specific reinforced fixation members90C. The micro movable substrate S1and the wiring board S2may be electrically connected to each other only by the reinforced fixation members90C.

FIGS. 20 to 23illustrate a modification of the micro movable device X1.FIG. 20is a plan view of the micro movable device X1according to the modification.FIG. 21is a plan view of a part of the micro movable device X1illustrated inFIG. 20.FIG. 22is a plan view of another part of the micro movable device X1illustrated inFIG. 20.FIG. 23is a sectional view ofFIG. 20taken along line XXIII-XXIII.

As illustrated inFIGS. 20 to 23, in the micro movable device X1, the reinforced fixation members90C are disposed, instead of the spacers90A, on conductive paths for applying a reference potential to the electrode portions12and60. In this point, the micro movable device X1according to the present modification differs from the micro movable device X1illustrated inFIGS. 1 to 11. In the micro movable device X1illustrated inFIGS. 20 to 23, the reinforced fixation members90C are joined to the pads82bof the wiring patterns82C on the wiring board S2. The pads82band the bump units91C are pressure-bonded to each other. The reinforced fixation members90C are joined to the pads35on the surfaces of the portions32dof the second layer32of the frame30in the micro movable substrate S1. The bump units91C are joined to the pads35with the adhesive portions92disposed therebetween. The reference potential is applied to the electrode portion12through the wiring patterns82C (including the pads82awhich serve as external connection terminals) on the wiring board S2, the reinforced fixation members90C on the pads82bof the wiring patterns82C, the pads35provided on the micro movable substrate S1and joined to the reinforced fixation members90C, the portions32dof the second layer32of the frame30in the micro movable substrate S1, the conductive vias34b, the portion31aof the first layer31, the connecting portion43, the portion21cof the first layer21of the frame20, the conductive via24c, the portion22aof the second layer22, the conductive vias24a, the portion21aof the first layer21, the connecting portions41, and the beam portion13of the oscillating portion10. The reference potential is applied to the electrode portion60through the wiring patterns82C (including the pads82awhich serve as external connection terminals) on the wiring board S2, the reinforced fixation members90C on the pads82bof the wiring patterns82C, the pads35provided on the micro movable substrate S1and joined to the reinforced fixation members90C, the portions32dof the second layer32of the frame30in the micro movable substrate S1, the conductive vias34b, the portion31aof the first layer31, the connecting portion43, and the portion21cof the first layer21of the frame20.

FIGS. 24 to 29illustrate a micro movable device X2according to a second embodiment.FIG. 24is a plan view of the micro movable device X2.FIG. 25is a plan view of a part of the micro movable device X2.FIG. 26is a plan view of another part of the micro movable device X2.FIGS. 27 to 29are sectional views ofFIG. 24taken along lines XXVII-XXVII, XXVIII-XXVIII, and XXIX-XXIX, respectively.

The micro movable device X2includes a micro movable substrate S3, a wiring board S4, spacers90A and90B, and reinforced fixation portions90C. According to the present embodiment, the micro movable device X2may be used as a micromirror device.

The micro movable substrate S3includes a plurality of micro movable units Xa having the structure similar to that of the above-described micro movable unit Xa. Each of the micro movable units Xa includes an oscillating portion10, frames20and30, a pair of connecting portions41, a pair of connecting portions42and43, and electrode portions50,60, and70. The micro movable units Xa are arranged in a single row along the direction of the axial center A1such that axial centers A2of all of the micro movable units Xa are parallel to each other. Similar to the micro movable unit Xa according to the first embodiment, the micro movable units Xa according to the present embodiment are also formed by subjecting a material substrate to processes using bulk micromachining technology, such as the MEMS technology. An SOI wafer, for example, may be used as the material substrate. The material substrate includes a first silicon layer, a second silicon layer, and an insulating layer interposed between the first and second silicon layers. The silicon layers are doped with impurities to apply conductivity thereto. Each of the above-mentioned portions of the micro movable unit Xa is formed in the first silicon layer or the second silicon layer. To facilitate understanding of the drawings, portions formed in the first silicon layer are shaded inFIG. 24. InFIG. 25, portions formed in the second silicon layer are illustrated as provided on the wiring board S4. In other words, inFIG. 25, portions formed in the first silicon layer, portions formed on the first silicon layer, and portions formed in the insulating layer are omitted.

In the micro movable device X2, the micro movable units Xa have a common frame30. A first layer31of the frame30has a portion31a, as described in the first embodiment, which continuously extends around all of the micro movable units Xa. A second layer32of the frame30includes portions32dwhich are common to all of the micro movable units Xa. The movable sections including the oscillating portions10and the frames20of all of the micro movable units Xa are surrounded by the common frame30. In the micro movable substrate S3in which the common frame30is formed, electrode portions12of the oscillating portions10, portions21aand21cof first layers21in the frames20, portions22aof second layers22in the frames20, the portions32dof the second layer32of the frame30, and the electrode portions60are electrically connected to each other in all of the micro movable units Xa.

As illustrated inFIG. 26, the wiring board S4of the micro movable device X2includes a base81, wiring patterns82A,82B, and82C, and pads83. The base81is made of a silicon material. Each of the wiring patterns82A,82B, and82C includes pads82aand82b. The pads82aserve as external connection terminals of the micro movable device X2.

As illustrated inFIGS. 27 to 29, each of the spacers90A included in the micro movable device X2includes a bump unit91A and an adhesive portion92. The spacers90A are disposed between the frame30in the micro movable substrate S3and the wiring board S4. Each of the bump units91A includes two bumps placed on top of each other. The bumps may be made of, for example, Au. The bump units91A are pressed against the pads82bin the wiring patterns82A to82C on the wiring board S4. In addition, the bump units91A are joined to the pads35on the frame30in the micro movable substrate S3by the adhesive portions92. The adhesive portions92may be made of, for example, a conductive adhesive. The conductive adhesive contains a conductive filler. In the present embodiment, the spacers90A electrically connect the micro movable substrate S3and the wiring board S4to each other.

As illustrated inFIGS. 27 to 29, each of the spacers90B included in the micro movable device X2includes a bump unit91B and an adhesive portion92. The spacers90B are disposed between the frame30in the micro movable substrate S3and the wiring board S4. Each of the bump units91B includes two bumps placed on top of each other. The bumps may be made of, for example, Au. The bump units91B are pressed against the pads83on the wiring board S4. In addition, the bump units91B are joined to the pads35on the frame30in the micro movable substrate S3by the adhesive portions92. The adhesive portions92may be made of, for example, conductive adhesive.

As illustrated inFIGS. 27 to 29, each of the reinforced fixation members90C of the micro movable device X2includes a bump unit91C and adhesive portions92and93. The reinforced fixation members90C are disposed between the frame30in the micro movable substrate S3and the wiring board S4. Each of the bump units91C includes two bumps placed on top of each other. The bumps may be made of, for example, Au. The bump units91C are pressed against the pads83on the wiring board S4. The bump units91C are joined to the pads35on the frame30in the micro movable substrate S3by the adhesive portions92. The adhesive portions92may be made of, for example, a conductive adhesive. The adhesive portions93are provided so as to cover the periphery of the bump units91C and join the micro movable substrate S3and the wiring board S4to each other. The adhesive portions93may be made of, for example, a conductive adhesive. Since the reinforced fixation members90C are provided, the micro movable substrate S3and the wiring board S4may be strongly fixed to each other.

As illustrated inFIGS. 27 to 29, each of the reinforced fixation members90C of the micro movable device X2is disposed between the corresponding pair of spacers90A and90B. The pairs of spacers90A and90B and the reinforced fixation portions90C illustrated inFIGS. 27 to 29are arranged in a line parallel to the axial centers A2of the corresponding micro movable units Xa. The pair of spacers90A and90B and the reinforced fixation member90C illustrated inFIG. 27are joined to the frame30at positions in a line parallel to the axial center A2of the corresponding micro movable unit Xa, as illustrated inFIG. 25. The pair of spacers90A and90B and the reinforced fixation member90C illustrated inFIG. 28are also joined to the frame30at positions in a line parallel to the axial center A2of the corresponding micro movable unit Xa, as illustrated inFIG. 25.

When the micro movable device X2is driven, the reference potential is commonly applied to the electrode portions12of the oscillating portions10and the electrode portions60of all of the micro movable units Xa. In this state, a drive potential is applied to the electrode portions50and70of selected micro movable units Xa. Thus, the oscillating portions10and the frames20of the micro movable units Xa are individually rotated, and the direction in which light is reflected by the mirror surfaces11aprovided on the land portions11of the respective micro movable units Xa may be changed individually. The reference potential is commonly applied to the electrode portions12of the oscillating portions10and the electrode portions60of all of the micro movable units Xa through the wiring patterns82C (including the pads82awhich serve as external connection terminals) on the wiring board S4, the spacers90A on the pads82bof the wiring patterns82C, the pads35provided on the micro movable substrate S3and joined to the spacers90A, the portions32dof the second layer32of the frame30in the micro movable substrate S3, the conductive vias34b, the portion31aof the first layer31, the connecting portions43, the portions21cof the first layers21of the frames20, the conductive vias24c, the portions22aof the second layers22, the conductive vias24a, the portions21aof the first layers21, the connecting portions41, and the beam portions13of the oscillating portions10. The reference potential may be, for example, a ground potential and is preferably maintained constant. The drive potential is applied to the electrode portions50and70of the selected micro movable units Xa in a manner similar to the application of the drive voltage to the electrode portions50and70of the micro movable unit Xa according to the first embodiment.

In manufacturing the micro movable device X2, the micro movable substrate S3illustrated inFIG. 30Ais formed by a method similar to the method for forming the micro movable substrate S1included in the micro movable device X1.

In addition, in the process of manufacturing the micro movable device X2, the bump units91A to91C, the conductive adhesive92′, and the reinforcing adhesive93′ are placed on the pads82band83on the wiring board S4, as illustrated inFIG. 30A, by a method similar to the method for placing the bump units91A to91C, the conductive adhesive92′, and the reinforcing adhesive93′ on the pads82band83on the wiring board S2included in the micro movable device X1.

As illustrated inFIG. 30B, the micro movable substrate S3and the wiring board S4are joined to each other such that the bump units91A to91C, the conductive adhesive92′, and the reinforcing adhesive93′ are disposed therebetween. In this processing, the conductive adhesive92′ and the reinforcing adhesive93′ are cured by applying heat, thereby forming the adhesive portions92and93.

Thus, the micro movable device X2is manufactured which includes the micro movable substrate S3, the wiring board S4, and the spacers90A and90B and the reinforced fixation members90C which are provided so as to join the micro movable substrate S3and the wiring board S4to each other.

In the process of joining the micro movable substrate S3and the wiring board S4to each other, a large amount of reinforcing adhesive93′ applied to the bump units91C is cured. Thus, the adhesive portions93of the reinforced fixation members90C are formed. The reinforcing adhesive93′ contracts when it is cured. Therefore, a stress is applied to the frame30in the micro movable substrate S3at positions where the reinforced fixation members90C are joined. For example, a tensile stress is applied in a direction such that the distance between the micro movable substrate S3and the wiring board S4decreases. However, as illustrated inFIGS. 27 to 29, each of the reinforced fixation members90C including the adhesive portions93is disposed between the corresponding pair of spacers90A and90B. Therefore, the frame30may be prevented from being deformed by the above-described stress. The spacers90A and90B and the reinforced fixation members90C resist the stress applied to the frame30at positions where the reinforced fixation members90C are joined. Therefore, the boundary between the adhesive portion93of each reinforced fixation member90C and the micro movable substrate S3serves as a point of force and the boundary between each of the spacers90A and90B and the micro movable substrate S3serves as a fulcrum, so that deformation of the frame30may be reduced if not prevented. As a result, in the micro movable device X2, spring constants of the connecting portions42and43after the processing of joining the micro movable substrate S3and the wiring board S4to each other may be prevented from being changed due to the joining process. Changes in the spring constants of the connecting portions42and43, which are included in the micro movable units Xa and connected to the frame30, are caused by the deformation of the frame30.

In addition, in the manufactured micro movable device X2, the volume of the adhesive portion93of each reinforced fixation member90C varies in accordance with the temperature variation. Therefore, a stress is applied to the frame30in the micro movable substrate S3at positions where the reinforced fixation members90C are joined. However, as illustrated inFIGS. 27 to 29, each of the reinforced fixation members90C including the adhesive portions93is disposed between the corresponding pair of spacers90A and90B. Therefore, the frame30may be prevented from being deformed by the above-described stress. The spacers90A and90B and the reinforced fixation members90C resist the stress applied to the frame30at positions where the reinforced fixation members90C are joined. Therefore, the boundary between the adhesive portion93of each reinforced fixation member90C and the micro movable substrate S3serves as a point of force and the boundary between each of the spacers90A and90B and the micro movable substrate S3serves as a fulcrum, so that deformation of the frame30may be prevented. As a result, in the micro movable device X2, spring constants of the connecting portions42and43in each micro movable unit Xa after the processing of joining the micro movable substrate S3and the wiring board S4to each other may be prevented from being changed due to the joining process.

As described above, the spring constants of the connecting portions42and43, which connect the movable section (the oscillating portion10, the frame20, the connecting portions41, the electrode portion50, and the electrode portion60) to the frame30in each micro movable unit Xa, after the process of manufacturing the micro movable device X2may be prevented from being changed from the spring constants before the manufacturing process. In this type of micro movable device X2, mechanical characteristics, such as resonance frequency of the movable section, may be adequately controlled. Therefore, degradation of performance of the device may be suppressed.

In the micro movable device X2, the base material of the micro movable substrate S3is a silicon material, as described above. The base81, which is the base material of the wiring board S4, is also made of a silicon material, as described above. Therefore, a difference between a change in the volume of the micro movable substrate S3and a change in the volume of the wiring board S4(support base) due to temperature variation may be reduced. As a result, a stress applied to the frame30in the micro movable substrate S3at positions where the reinforced fixation members90C are joined may be reduced.

In the micro movable device X2, the pairs of spacers90A and90B and the reinforced fixation portions90C illustrated inFIGS. 27 to 29are arranged in a line parallel to the axial centers A2of the corresponding micro movable units Xa. The pair of spacers90A and90B and the reinforced fixation member90C illustrated inFIG. 27are joined at positions in a line parallel to the axial center A2of the corresponding micro movable unit Xa. The pair of spacers90A and90B and the reinforced fixation member90C illustrated inFIG. 28are also joined at positions in a line parallel to the axial center A2of the corresponding micro movable unit Xa. Therefore, variation in the spring constants of the connecting portions42and43may be suppressed.

In the micro movable device X2, each of the reinforced fixation members90C may include a plurality of bump units91C, a plurality of adhesive portions92provided at the top of the respective bump units91C, and an adhesive portion93provided so as to cover the periphery of the bump units91C.

The shape of the pattern of the portions32ato32dof the second layer32of the frame30in the micro movable substrate S3, the shape of the wiring patterns82A to82C and the pattern of the pads83on the wiring board S4, and the arrangement of each set of the spacers90A and90B and the reinforced fixation member90C, which are arranged in a single row, may be changed such that the micro movable substrate S3and the wiring board S4are electrically connected to each other by specific reinforced fixation members90C. The micro movable substrate S3and the wiring board S4may be electrically connected to each other only by the reinforced fixation members90C.

The above-described micro movable devices X1and X2may be used as components of an optical switching apparatus.

FIG. 31is a schematic diagram illustrating an optical switching apparatus300of a spatial optical coupling type according to a third embodiment. The optical switching apparatus300includes a pair of micromirror arrays301and302, an input fiber array303, an output fiber array304, and a plurality of microlenses305and306. The input fiber array303includes a plurality of input fibers303a. The micro mirror array301includes a plurality of micromirrors301awhich correspond to the input fibers303a. The output fiber array304includes a plurality of output fibers304a. The micro mirror array302includes a plurality of micromirrors302awhich correspond to the output fibers304a. Each of the micromirrors301aand302aincludes a mirror surface which reflects light. The orientations of the mirror surfaces of the micromirrors301aand302aare controllable. The above-described micro movable device X1may be used as each of the micromirrors301aand302a. Alternatively, the above-described micro movable device X2may be used as each of the micro mirror arrays301and302. The microlenses305are disposed so as to face the input fibers303aat ends thereof. The microlenses306are disposed so as to face the output fibers304aat ends thereof.

In the optical switching apparatus300, light beams L1emitted from the input fibers303apass through the corresponding microlenses305. Accordingly, the light beams L1are converted into parallel beams and are guided to the micro mirror array301. Then, the light beams L1are reflected by the corresponding micromirrors301a, and are deflected toward the micro mirror array302. At this time, the mirror surfaces of the micromirrors301aare oriented in specific directions so that the light beams L1may be incident on the desired micromirrors302a. Then, the light beams L1are reflected by the micromirrors302aand are deflected toward the output fiber array304. At this time, the mirror surfaces of the micromirrors302aare oriented in specific directions so that the light beams L1may be incident on the desired output fibers304a.

Thus, in the optical switching apparatus300, the light beams L1emitted from the respective input fibers303aare deflected by the micro mirror arrays301and302and are caused to reach the desired output fibers304a. In other words, the input fibers303aand the output fibers304aare connected to each other in one-to-one correspondence. In addition, by changing the deflecting angles of the micromirrors301aand302a, the output fibers304aat which the light beams L1arrive may be changed.

Characteristics of an optical switching apparatus which switches a transmission path of an optical signal, which is transmitted via an optical fiber, from a first fiber to a second fiber include transmission capacity, transmission speed, and reliability in the switching operation. From this point of view, a micromirror device formed by micromachining techniques is suitable for use as a switching device included in the optical switching apparatus. In the case where the micromirror device is used, a switching process of an optical signal between an input optical transmission path and an output optical transmission path may be performed by the optical switching apparatus without converting the optical signal into an electrical signal.

FIG. 32is a schematic diagram illustrating an optical switching apparatus400of a wavelength selection type according to a fourth embodiment. The optical switching apparatus400includes a micromirror array401, a single input fiber402, three output fibers403, a plurality of microlenses404aand404b, a spectral element405, and a condensing lens406. The micromirror array401includes a plurality of micromirrors401a. The number of input fibers402is not limited to one. The number of output fibers403is not limited to three. The micromirrors401amay be, for example, arranged along a single row in the micromirror array401. Each of the micromirrors401aincludes a mirror surface which reflects light. The orientations of the mirror surfaces of the micromirrors401aare controllable. The micro movable device X1may be used as each of the micromirrors401a. Alternatively, the micro movable device X2may be used as the micromirror array401. The microlens404ais disposed so as to face the input fiber402at an end thereof. The microlenses404bare disposed so as to face the output fibers403at ends thereof. The spectral element405is a reflective diffraction grating at which light is reflected at different degrees of reflection depending on the wavelength thereof.

In the optical switching apparatus400, a light beam L2including components of different wavelengths is emitted from the input fiber402. The thus-emitted light beam L2is collimated when the light beam L2passes through the microlens404a. The light beam L2is reflected by the spectral element405. At this time, the components of different wavelengths of the light beam L2are reflected at different angles. The reflected light components pass through the condensing lens406. Accordingly, the light components are collected at the corresponding micromirrors401ain the micromirror array401in accordance with the wavelengths thereof. The light components having different wavelengths are reflected by the corresponding micromirrors401ain specific directions. At this time, the mirror surfaces of the micromirrors401aare oriented in specific directions so that the light components having the corresponding wavelengths may reach the desired output fibers403. The light components reflected by the micromirrors401apass through the condensing lens406, the spectral element405, and the microlenses404b, and are incident on the selected output fibers403. Thus, the light components having the desired wavelengths may be selectively obtained from the light beam L2by the optical switching apparatus400.