JP2007248731A - Micromirror, and optical component and optical switch using the micromirror - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a micromirror having the advantage of antishock characteristic and a high speed control. <P>SOLUTION: The micromirror is provided with: a movable mirror 111 having a reflection face 112 on one face; a movable mirror substrate 110 to which the movable mirror 111 is connected; and beams 114 which connect the movable mirror 111 and the movable mirror substrate 110 and support the movable mirror 111 turnably with respect to the movable mirror substrate 110. The reflection face 112 is composed of a film formed on the base body 119 of the movable mirror 111, the base body 119 has a thin portion having a thickness smaller than that of the portion having the reflection face 112, and the thin portion has a height different from that of the portion having the reflection face 112 at least on the side of the face having the reflection face, thus the loss due to the warpage or the like of the reflection face is suppressed while suppressing the increase in mass. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a micromirror that reflects a light beam and changes the traveling direction of the light beam, and an optical component such as an optical switch and a photodetector.

  Many applications of MEMS technology to optical communication components and optical communication systems have been proposed. For example, a micromirror is disclosed in which polycrystalline silicon laminated on a silicon substrate is used as a member. The micromirror is supported by a beam formed integrally with the micromirror, and is formed in a floating state on the substrate. The micromirror is an electrostatic drive type micromirror, and can perform a biaxial rotation operation by applying a potential difference between an electrode formed under the micromirror and the micromirror. The mirror thickness of the micromirror is about several μm (Patent Document 1).

As another example, a micromirror is disclosed in which a silicon on insulator (SOI) substrate in which a silicon oxide (SiO ₂ ) layer is sandwiched between single crystal silicon (Si) layers is etched to form single crystal silicon as a member. ing. The micromirror is intended for application to an optical cross-connect switch (Non-Patent Document 1). The micromirror is disposed on a separately formed electrode formation substrate, and a biaxial rotation operation can be performed by applying a potential difference between the electrode disposed below the micromirror and the micromirror. The mirror thickness of the micromirror is 10 μm by using an SOI substrate.

Japanese Patent Laid-Open No. 2001-221962 “Conference Digest of 2002 IEEE / LEOS International Conference on Optical MEMs”, August 20-23, 2002, p.11-12 (TuB1)

  In optical communication parts, it is extremely important to ensure the optical characteristics of the optical parts used. When the optical component is a mirror, the optical characteristic to be ensured is that no loss occurs due to reflection on the reflection surface of the mirror. The loss at the reflecting surface of the mirror is mainly caused by the scattering of the wave front caused by the reflectance, the scattering caused by the roughness of the reflecting surface, or the warping or waviness of the reflecting surface. In the example disclosed in Patent Document 1, there are problems with the roughness and warping of the reflecting surface, and it is difficult to achieve low loss. The example disclosed in Non-Patent Document 1 is an example in which a mirror is formed by bulk micromachining for the purpose of solving the problems such as roughness and warpage in Patent Document 1. However, even in Non-Patent Document 1, sufficient consideration is required at the time of forming a reflective film in order to suppress warping particularly when a temperature change is applied. The mirror warp is caused by the mirror thickness not being sufficiently large with respect to the residual stress and thermal stress of the formed reflective film. Therefore, it is possible to ensure optical characteristics by increasing the thickness of the mirror. However, increasing the mirror thickness unnecessarily affects other characteristics. Specifically, as the mirror mass increases, the resistance to breakage, particularly breakage when an impact is applied, decreases. Furthermore, the operating speed is lowered, and the high speed controllability is lowered. One solution is to increase the force to support or hold the mirror in order to suppress the drop in impact resistance and high-speed controllability. For example, when using electrostatically driven micromirrors, Since the electric driving force is small, it is difficult to increase the supporting force and holding force. That is, in the conventional micromirror, it is difficult to ensure both optical properties and improve impact resistance and controllability.

  In view of the above problems, the present invention provides a micromirror having a structure that can easily suppress loss due to warping of a reflecting surface while suppressing an increase in mass, and is advantageous in impact resistance and high-speed controllability. With the goal. Further, by applying the micromirror, an optical component and an optical switch that are superior in optical characteristics, impact resistance, and high speed controllability are provided.

  The present invention relates to a movable mirror having a reflecting surface on one surface, a movable mirror substrate to which the movable mirror is coupled, the movable mirror and the movable mirror substrate, and the movable mirror as the movable mirror substrate. And a beam that is rotatably supported. The reflecting surface is formed of a film formed on the base of the movable mirror, and the base has a thin portion having a thickness smaller than that of the portion having the reflecting surface. The thin portion is a micromirror having a surface having a height different from the height of the portion having the reflective surface at least on the surface having the reflective surface. By providing a thin portion on the base at a portion other than the reflecting surface necessary for the function as a mirror, the mass of the movable mirror is reduced while ensuring a necessary thickness for suppressing the warpage in the portion having the reflecting surface. Therefore, it is possible to provide a micromirror that is advantageous in optical characteristics, impact resistance, and high-speed controllability.

  Further, the micromirror includes a mirror electrode portion formed on a surface opposite to the surface having the reflecting surface, and a drive electrode portion disposed to face the mirror electrode portion, and the movable mirror Is preferably driven by an electrostatic force applied between the drive electrode portion and the mirror electrode portion. Since the movable mirror mass is effectively reduced by providing the thin portion, the micromirror according to the present invention is particularly suitable for the electrostatically driven micromirror having the above-described configuration with relatively weak driving force. The thin part is formed by reducing the thickness by changing the surface height on the side having the reflecting surface of the base, so the surface opposite to the surface having the reflecting surface is necessary for driving. It is possible to ensure a wide electrode surface.

  Furthermore, in the micromirror, it is preferable that the reflecting surface and the mirror electrode portion are substantially parallel. Such a configuration prevents the manufacturing process from becoming complicated and contributes to an improvement in productivity.

  Further, in the micromirror, the movable mirror rotates about the beam as a central axis, the central axis is located at the center in the in-plane direction of the movable mirror, and the reflecting surface straddles the central axis. Is preferred. A portion having a reflecting surface thicker than a thin portion straddles the central axis, so that an increase in moment of inertia can be effectively suppressed, contributing to improvement in controllability.

  Furthermore, it is preferable that the micromirror has a thick portion having a thickness larger than the thin portion on the surface side having the reflective surface, in addition to the portion having the reflective surface. Providing the thick portion effectively acts to suppress the warp of the movable mirror and contributes to the suppression of deterioration of the optical characteristics.

  Furthermore, in the micromirror, it is preferable that the thick portion surrounds the portion having the reflective surface in a frame shape with at least a portion sandwiching the thin portion. The frame-shaped thick portion is more preferable for suppressing warpage because it firmly supports the movable mirror.

  Furthermore, in the micromirror, it is preferable that the thickness of the movable mirror is maximized in the portion having the reflective surface. The configuration has an advantage that it can be easily manufactured, and contributes to a reduction in moment of inertia.

  Moreover, the optical component of the present invention is an optical component using any one of the above-described micromirrors as an optical deflection unit. By using the micromirror that is advantageous in optical characteristics, impact resistance, and high-speed controllability, an optical component that makes full use of the characteristics can be realized. Here, the optical component is a component that is widely used for light, such as an optical switch, a photodetector, or the like, and may be any device that requires light deflecting means.

An optical switch according to the present invention includes any one of the above-described micromirrors, one or more input side optical fibers, an input side collimating lens, one or more output side optical fibers, and an output side collimating lens. ,
The optical switch selects an output side optical fiber to which the light beam is recombined by deflecting the light beam emitted from the input side optical fiber by the micromirror. Since the micromirror according to the present invention can be reduced in weight while suppressing warpage, it is suitably used for an optical switch that requires integration.

  Furthermore, in the optical switch, it is preferable that a light beam is condensed on a reflection surface of the micromirror using a condensing optical system. Such a configuration contributes to miniaturization of the optical switch, and as a result, is advantageous for integration of the optical switch.

  Further, in the optical switch, the condensing optical element is a cylindrical lens, the input side optical fiber is one, the output side optical fiber is two, and the movable mirror is the input side optical fiber. And an optical path between the input optical fiber and the other optical fiber of the output side optical fiber, and a first posture that forms an optical path between the optical fiber and the output side optical fiber. It is preferable to select a second posture that forms a mirror, and in the first posture and the second posture, the movable mirror has a contact point with another member. The optical switch having such a configuration to which the micromirror according to the present invention is applied has high accuracy and reliability because each posture is stable, and can contribute to miniaturization. Combined with the effect of the mirror, an excellent optical switch can be realized.

  According to the present invention, it is possible to provide a micromirror that has a structure that easily suppresses a loss due to warping of a reflecting surface and the like while suppressing an increase in mass and is advantageous in impact resistance and high-speed controllability.

Embodiments of the present invention will be described below with reference to the drawings. In addition, this invention is not limited by these Examples.

  FIG. 1 is a cross-sectional view of an embodiment of a micromirror according to the present invention. In this embodiment, an electrostatic drive micromirror using an electrostatic force as a driving force will be described as an example. However, the driving force is not limited to an electrostatic force, and an electromagnetic force, a piezo element, a thermal deformation, a bimorph element, or the like is used. A micromirror with a driving force may be used. However, since the micromirror of the present invention is suitable when the driving force is weak or when the driving force is proportional to the area, the micromirror is more preferably configured as an electrostatically driven micromirror.

  The movable mirror 111 has a reflecting surface 112 on one surface. The movable mirror 111 is connected to the movable mirror substrate 110 by a beam 114, and the beam 114 supports the movable mirror 111 so as to be rotatable with respect to the movable mirror substrate 110. The beam 114 has elasticity, and is connected to the movable mirror as a pair of beams on both sides of the movable mirror. The movable mirror 111 is rotated about the beam 114 as a central axis, and is inclined within a predetermined angle range by the applied driving force. In the embodiment of FIG. 1, the electrode substrate 120 for applying a voltage is disposed opposite to the movable mirror 111 and also opposite to one surface having the reflecting surface of the movable mirror 111, that is, opposite to the electrode substrate 120. A mirror electrode portion 113 is provided on the side surface. On the electrode substrate 120, a drive electrode portion 121 is disposed so as to face the mirror electrode portion 113. The mirror electrode portion 113 and the reflecting surface 112 are substantially parallel planes. A configuration in which these are parallel to each other is easy to manufacture and ensures high accuracy. “Substantially parallel” means that a manufacturing error is allowed. The reflective surface 112 is configured by forming a reflective film 132 on a base 119 of a movable mirror formed of at least one of a semiconductor and a semiconductor oxide.

  The base 119 has a thin portion 117 having a thickness smaller than that of a portion having a reflecting surface. The thin portion 117 has a surface having a height different from the height of the portion having the reflective surface on the surface having the reflective surface. That is, on the surface having the reflective surface, the surface of the thin portion is lower than the surface of the portion having the reflective surface, whereby a concave portion is formed in the movable mirror 111. In order to apply a driving force such as electrostatic force, the movable mirror needs to have a certain size and spread in order to secure an electrode area and the like, but the reflecting surface is not necessarily formed on the entire movable mirror. Absent. The area of the reflecting surface 112 is limited to a necessary and sufficient size to reflect the light beam. On the other hand, the area of the mirror electrode portion 113 is made as large as possible without causing inconvenience in the configuration of the micromirror 100 to generate a strong electrostatic force. It is desirable that the portion not having the reflecting surface 112 be as thick as the beam 114 as much as possible.

Here, the warp R of the reflecting surface 112 includes the thickness h of the base 119, the Young's modulus E of the base 119, the Poisson's ratio ν of the base 119, the thickness t of the reflective film 132, and the thickness of the reflective film 132. Using stress σ, R = (E × h ² ) / {6 × (1−ν) × t × σ}
It is represented by FIG. 14 shows the relationship between the ratio of the thickness of the base portion and the thickness of the thin portion having the reflecting surface and the warpage resistance. The criterion for warpage resistance was a value when the thickness of the base portion of the portion having the reflective surface was the same as that of the thin portion. Warpage resistance can be improved 10 times or more by setting the thickness of the portion having the reflecting surface 112 to 3.2 times or more of the thin portion. By adopting the above configuration, it is possible to suppress an increase in mass and moment of inertia of the movable mirror 111 while preventing the reflection surface 112 from warping. Therefore, in this embodiment, a reflecting surface having a width necessary for the reflecting function is secured, and a thin portion is provided on the base 119 in other portions, thereby reducing the weight of the movable mirror and improving the high-speed controllability. Is planned. Further, in order to prevent mirror warpage or the like, it is necessary to make the base 119 thick. However, since the thin portion 117 is provided in this embodiment, the thickness of the base is increased while suppressing an increase in mirror mass. Is possible.

  Further, in the present embodiment shown in FIGS. 1 and 2, in addition to the portion having the reflection surface 112, the thick portion 116 having a thickness larger than the thin portion 117 has the reflection surface 112 with the thin portion 117 interposed therebetween. The part is surrounded by a frame. The thick portion is formed in a linear shape when viewed from the reflecting surface side. In the present embodiment, the thickness of the base of the portion having the reflecting surface 112 and the thick portion 116 is the same. Such a thick portion 116 is not necessarily provided, and effects such as reduction in the weight of the mirror and prevention of warping can be obtained without providing the thick portion. However, it is preferable to provide a thick part in addition to the part having the reflecting surface, particularly from the viewpoint of preventing the warp of the mirror, particularly the warp at the thin part 117.

  In FIG. 1, the central axis of rotation is located at the center in the in-plane direction of the movable mirror, and the reflection surface 112 straddles the central axis 115 when viewed from the reflection surface side. . The center means that an error range that does not hinder the symmetrical operation of the movable mirror is allowed. With this configuration, an increase in the moment of inertia of the movable mirror 111 can be effectively suppressed, which contributes to an improvement in controllability.

  Further, in the configuration of FIG. 1, the thickness of the movable mirror 111 is maximized in the portion having the reflecting surface 112, and this configuration has an advantage that it can be easily manufactured. This manufacturing method will be described later.

  The electrode substrate 120 has one or more, for example, a pair of drive electrode portions 121. An electrostatic actuator is configured between the drive electrode unit 121 and the mirror electrode unit 113. By applying a potential difference between the drive electrode unit 121 and the mirror electrode unit 113, static electricity is provided between the two. Electric power is applied and the movable mirror 111 is operated.

The spacer 130 is disposed to provide a certain space between the electrode substrate 120 and the movable mirror 111. The spacer 130 may be made of a member independent of the movable mirror substrate 110 or the electrode substrate 120, or may be formed integrally with the movable mirror substrate 110 or the electrode substrate 120. FIG. 1 shows an example in which the spacer 130 is integrally formed with the electrode substrate 120. The movable mirror substrate 110 is made of, for example, a silicon (Si) substrate, an SOI substrate in which a silicon oxide (SiO ₂ ) layer is sandwiched between silicon (Si) layers, a metal substrate, or the like. It is desirable that the movable mirror 111 improve the reflectance by forming a reflective film on the reflective surface 112. Gold (Au), aluminum (Al), or various multilayer films can be used as the reflective film. For the mirror electrode portion 113 of the movable mirror 111, for example, gold (Au), aluminum (Al), chromium (Cr), nickel (Ni), copper (Cu), platinum (Pt), or titanium (Ti) alone or A conductive film is formed by appropriately stacking. However, when the material constituting the movable mirror 111 has sufficient conductivity, the conductive film does not need to be formed on the mirror electrode portion 113.

  The spacer 130 can be manufactured using various materials. In the case of electrostatic driving, depending on the configuration of the micromirror 100, the surface of the spacer 130 can be conductive or insulative. For example, by making the surface of the spacer 130 conductive, the mirror electrode portion 113 of the movable mirror 111 can be part of a path that electrically connects an external circuit (not shown). Alternatively, by making the surface of the spacer 130 insulative, the spacer 130 can be disposed on the electrode substrate 120 without avoiding the wiring 123 on the electrode substrate 120. When the spacer 130 is formed independently of the movable mirror substrate 110 or the electrode substrate 120, the material constituting the spacer 130 is a material having a thermal expansion coefficient close to or matched to that of the movable mirror substrate 110 and the electrode substrate 120. It is desirable.

  The base of the part constituting the reflecting surface 112 is made thicker than the beam 114. The movable mirror 111 is provided with as many thin portions as possible, preferably the same thickness as the beam 114. However, there may be a part that is partially thicker than the beam 114, such as the thick part. The beam 114 supports the movable mirror 111 on the movable mirror substrate 110 and gives a restoring force to the displacement of the movable mirror 111. The beam 114 also has a function as a path for electrically connecting the mirror drive electrode portion 113 to an external circuit. However, the electrical connection between the mirror drive electrode portion 113 of the movable mirror 111 and an external circuit (not shown) is not shown. In FIG. 2, a folded beam is illustrated as the beam 114, but the figure does not limit the beam structure. For example, the beam 114 may be a straight beam, and the number of turns may be increased or decreased.

  FIG. 2 does not limit the shape of the movable mirror 111 on the reflecting surface 112 side. 3A, 3B and 3C illustrate another embodiment of the micromirror according to the present invention. FIG. 3A shows an embodiment in which a thick portion is provided only on the reflecting surface 112 disposed at the center of the movable mirror 111. The portions other than the portion having the reflecting surface 112 are all thin portions 117, and the effect of reducing mass and moment of inertia is greatest. FIG. 3B shows an embodiment having a reflecting surface 112 at the center of the movable mirror 111 and having a thin and thick portion 116 in the longitudinal direction of the mirror, that is, in the direction perpendicular to the rotation axis. The thick portions are extended from the portion having the reflecting surface 112 in a thin line shape toward the both ends in the longitudinal direction. The thickness of the thick portion 116 is matched with the thickness of the portion having the reflecting surface 112. The thick portion 116 has an effect of suppressing the thin portion 117 from being deformed by residual stress or thermal stress. FIG.3 (c) is another embodiment regarding the arrangement | positioning method of the thick part 116 which has the same effect as FIG.3 (b). Each thick portion extends from the portion having the reflecting surface 112 in a narrow line shape toward both ends in the longitudinal direction. Since the area of the thick part 116 is smaller than that in FIG. 3B, the mass and the moment of inertia are superior to the embodiment in FIG.

FIG. 4A shows the electrode substrate 120 illustrated in FIG. 1 as viewed from the movable mirror substrate 110 side. The electrode substrate 120 is made of, for example, a silicon (Si) substrate, an SOI substrate in which a silicon oxide (SiO ₂ ) layer is sandwiched between silicon (Si) layers, a metal substrate, or an insulator substrate (eg, a glass substrate or a ceramic substrate). To do. When the material for forming the electrode substrate 120 is conductive, an insulating film (for example, oxide film SiO ₂ or nitride film SiN _{x in} the case of silicon) is formed on the surface of the electrode substrate 120, and the conductive film is formed on the insulating film. The drive electrode portion 121, the wiring 123, and the electrode pad 124 are formed. The conductive film is formed of, for example, gold (Au), aluminum (Al), chromium (Cr), nickel (Ni), copper (Cu), platinum (Pt), or titanium (Ti) alone or appropriately stacked. As another manufacturing method, the drive electrode portion 121 can be formed by performing screen printing on a ceramic substrate.

  Next, the movement of the movable mirror will be described. As shown in FIG. 4A, a drive electrode portion 121 for driving the movable mirror 111 with an electrostatic actuator is formed on the electrode substrate 120. Even when the movable mirror 111 rotates until it contacts the electrode substrate 120, the drive electrode portion 121 and the movable mirror 111 are not electrically short-circuited. Specifically, a method of arranging the drive electrode unit 121 only at a position where the drive electrode unit 121 and the movable mirror 111 do not contact each other, a method of covering the drive electrode unit 121 at least partially with an insulating film, or the like is applied. FIG. 4A shows an example in which the electrode 121 is disposed only at a position where the electrode 121 and the movable mirror 111 do not contact each other. A protrusion is formed on the electrode substrate 120 at a position corresponding to the lower portion of the rotation center axis 115 of the movable mirror 111. For example, one end (mirror edge) 118 of the movable mirror 111 is in contact with the electrode substrate 120, and the vicinity of the center of the surface of the movable mirror on the side where the mirror electrode is formed is in contact with the protrusion 122. The operating angle of the mirror 111 can be given mechanically and stably.

  The movable mirror 111 illustrated in FIGS. 3A, 3 </ b> B, 3 </ b> C, and 3 </ b> D changes the shape of the mirror end 118 for the purpose of reducing the contact area between the movable mirror 111 and the electrode substrate 120. Embodiments are shown. By reducing the contact area, when the movable mirror 111 contacts the electrode substrate 120 during operation, it contributes to suppression of adhesion between the movable mirror 111 and the electrode substrate 120. 3A, 3 </ b> B, 3 </ b> C, and 3 </ b> D show examples of the shape on the reflecting surface side and the shape of the mirror end portion 118, the combination of both is not limited. In particular, in the embodiment of FIG. 3B, since the curved line is formed at the mirror end 118, the movable mirror 111 and the electrode substrate 120 are in point contact, and the contact area reduction effect is greatest. FIG. 3D shows an example in which the mirror end portion 118 is not a thin portion. In the embodiment of FIGS. 3A and 3B, the thin portion 117 has a contact portion between the movable mirror 111 and the electrode substrate 120. However, in the embodiment of FIGS. The thick portion 116 has a contact portion with the electrode substrate 120. In the embodiment of FIG. 3C, a mirror end 118 having a thickness can be confirmed from the reflecting surface 112 side. However, the mirror end part having the thick part is a part. In the embodiment of FIG. 3D, the mirror end portion 118 having a thick portion is realized by partially processing the mirror electrode portion 113 side. In the form of FIG. 3D, the entire mirror end has a thick portion. In any form, even when the mirror end portion 118 collides with the electrode substrate 120, the mirror end portion 118 has a thick portion, so that it is rigid and hardly breaks.

  FIGS. 4B and 4C show another embodiment of the electrode substrate 120. The electrode substrate 120 shown in FIGS. 4B and 4C is an example of reducing the contact area when the movable mirror 111 and the protrusion 122 are in contact with each other. FIG. 4B shows an example in which the protrusion 122 is formed into a dot shape, and FIG. 4C shows an example in which the protrusion 122 is shortened and divided.

  The micromirror 100 may have a structure without the protrusion 122. In this case, the micromirror 100 having no protrusion 122 can be realized by eliminating the protrusion 122 of FIGS. 1 and 4. FIGS. 6A and 6B described later are examples of the micromirror 100 that does not have the protrusion 122. Even in the micromirror 100 having no protrusion 122, the shape shown in FIGS. 3A, 3B, 3C, and 3D can be applied to the shape on the reflecting surface 112 side and the shape of the mirror end portion 118. .

  Further, as described above, it is preferable that the thickness of the movable mirror 111 is maximized in the portion having the reflecting surface 112. This is because such a configuration makes it easy to manufacture. As an example of a manufacturing method of the movable mirror substrate 110 having the above structure, a manufacturing method using an SOI substrate will be described with reference to FIGS. An SOI substrate is used as a substrate on which the movable mirror substrate 110 is formed (FIG. 5A). A mirror electrode portion 113 is formed on the active layer 173 (Si layer) side of the SOI substrate, and a reflective surface is formed on the base layer (Si layer) 171. The SOI substrate is mirror-polished on both sides. The reason why the mirror electrode portion 113 is formed in the active layer 173 (Si layer) is that the active layer (Si layer) 173 side is thinner than the base layer (Si layer) 171 side. If the 173 side is thicker than the base layer (Si layer) 171 side, the reflecting surface 112 is formed on the active layer (Si layer) 173 side. Usually, since the active layer (Si layer) 173 side is thinner than the base layer (Si layer) 171 side, a manufacturing method when the mirror electrode portion 113 is formed on the active layer (Si layer) 173 side will be described below.

On the surface on the active layer (Si layer) 173 side, the shape of the mirror electrode portion 113 and the shape of the beam 114 are patterned by photolithography using a mask material such as a photoresist, an aluminum film, a silicon oxide film, and dry etching is performed ( FIG. 5B). The arrows shown in FIG. 5B indicate the direction of etching. The thickness of the beam 114 is given by the thickness of the active layer (Si layer) 173. The movable mirror shape on the reflecting surface 112 side is patterned on the base layer (Si layer) 171 side with a mask material such as a photoresist, an aluminum film, a silicon oxide film, and dry etching is performed (FIG. 5C). The arrows shown in FIG. 5C indicate the direction of etching. The movable mirror shape to be patterned on the reflecting surface 112 side is, for example, the shape shown in FIG. Since the thickness of the portion having the reflective surface 112 is given by the thickness of the base layer (Si layer) 171, the thickness of the movable mirror 111 is maximum at the portion having the reflective surface 112. The thickness of the thin portion 117 thinned by dry etching is the thickness of the active layer (Si layer) 173 plus the intermediate layer (SiO ₂ layer) 172. The intermediate layer (SiO ₂ layer) 172 is removed by wet etching (FIG. 5D). The arrows shown in FIG. 5D indicate the etching progress direction. By this process, the movable mirror is connected to the movable mirror substrate 110 only by the beam 114. That is, it is in a state of being rotatable around the central axis 115 provided by the beam 114. The thickness of the thin portion 117 thinned by dry etching matches the thickness of the beam 114. An element constituting the movable mirror in the state shown in FIG. That is, the base 119 indicates a portion of the movable mirror 111 that is formed of only the substrate used as a constituent material. Finally, a reflective film is formed on the reflective surface 112, and a conductive film is formed on the mirror electrode portion 113, for example, by sputtering (FIG. 5E).

In the case of the method for manufacturing the movable mirror substrate 110 using the above-described SOI substrate, the thickness of each part of the movable mirror 111 can be controlled by the thickness of each layer of the SOI substrate, so that the manufacturing is easy. The reflecting surface 112 and the mirror electrode portion 113 are particularly required to be flat in order to maintain the optical characteristics. The flatness of the reflecting surface 112 and the mirror electrode portion 113 is ensured by the flatness of the SOI substrate whose both surfaces are mirror-polished. In the example of the manufacturing method described above, since the etching surface is not used as the reflection surface 112, it is not necessary to request flatness of the etching surface. In the above-described procedure, the intermediate layer (SiO ₂ layer) 172 of the SOI substrate can be used as an etch stop layer in dry etching (FIGS. 5B and 5C), so that the manufacturing can be facilitated. Similarly, when a layer in which the etch rate is changed by doping a dopant and a silicon substrate that functions as an etch stop layer is used as a material, the movable mirror substrate 110 can be easily manufactured. Description of an example of a manufacturing method using the substrate is based on a manufacturing method using an SOI substrate, and thus the description is omitted.

  In addition, the manufacturing method mentioned above is an example, Comprising: The manufacturing method of the micromirror 100 of this invention is not limited. For example, a structure in which silicon on the base layer (Si layer) 171 side is partially etched to an appropriate depth (for example, half) and the etching surface is used as the reflection surface 112 may be employed. FIG. 6A shows an embodiment of the electrostatically driven micromirror 100 in which the movable mirror 111 is etched by a certain amount and the etched surface is the reflecting surface 112. The reflective surface 112 is lower than the surface of the movable mirror substrate 110, and the portion having the reflective surface 112 is thinner than the movable mirror substrate 110. Further, the surface of the thick part 116 formed is also lower than the surface of the movable mirror substrate 110, and the thick part is also thinner than the movable mirror substrate 110. In the example of FIG. 6A, the thickness is the same as that of the reflecting surface 112. In the configuration of FIG. 6A, the movable mirror substrate 110 can be made thick, and the mass of the movable mirror substrate can be reduced while keeping the rigidity of the substrate high. In this embodiment, the electrode substrate 120 does not have the protrusion 122. However, the presence or absence of the protrusion 122 may be selected according to the use of the micromirror 100.

  As another example, a configuration example in which the thickness of the thick portion 116 is thinner than the thickness of the portion having the reflecting surface 112 and thicker than the thickness of the thin portion 117 which is the thinnest portion of the movable mirror 111 is shown in FIG. Shown in b). The configuration shown in FIG. 6B can be realized, for example, by intentionally generating side etching (the progress of etching from the side surface by the etchant that wraps around from the side surface of the mask) in the thick portion 116. Alternatively, it is realized by intentionally etching the thick portion 116 in the middle of the etching process of FIG. 5C by making the mask thickness of the portion having the reflecting surface 112 thicker than the mask thickness of the thick portion 116. Can do. By reducing the thickness of the thick portion 116, the mass and moment of inertia of the movable mirror 111 can be reduced. In particular, reducing the thickness portion 116 near the mirror end portion 118 effectively contributes to the reduction of the moment of inertia. Although not clearly shown in the figure, the thickness of the thin portion 116 may not be uniform, and may be partially thinned. For example, the thickness near the reflecting surface 112 is the same as the thickness of the reflecting surface 112, and the thickness can be gradually reduced as the mirror end 118 is approached.

Next, an example of a method for manufacturing the electrode substrate 120 will be described with reference to FIGS. The electrode substrate 120 in FIG. 7 is an example in which the spacer 130 is formed integrally with the electrode substrate, and corresponds to a manufacturing example of the electrode substrate 120 used in the micromirror 100 in FIG. A silicon (Si) substrate 181 is used as a substrate on which the electrode substrate 120 is formed (FIG. 7A). The surface of the spacer 130 is patterned on the surface with a mask material such as a photoresist or a silicon oxide film by photolithography, and anisotropic wet etching using KOH (potassium hydroxide aqueous solution) is performed on the etchant (FIG. 7B). ). The arrows shown in FIG. 7B indicate the direction of etching. In this step, a difference between the height of the spacer 130 and the height of the protrusion 122 is formed. The shape of the spacer 130 and the shape of the protrusion 122 are patterned on the surface by photolithography, and anisotropic wet etching using KOH or the like is performed on the etchant (FIG. 7C). The arrows shown in FIG. 7C indicate the direction of etching. A thermal oxide film (SiO ₂ ) is formed as an insulating film on the surface of the silicon (Si) substrate 181 (FIG. 7D). Finally, conductive drive electrode portions 121, wirings 123, and electrode pads 124 are formed by sputtering, for example (FIG. 7E).

  The above-described manufacturing method is an example, and the manufacturing method of the electrode substrate 120 is not limited. For example, the etching method may be isotropic wet etching or dry etching. Alternatively, the protrusion 122 and the spacer 130 can be formed by stacking. Since the height of the spacer 130 and the height of the protrusion 122 are different in the electrode substrate 120 of this embodiment, the etching is performed twice. However, the heights of the both may be the same, and in this case, the number of times of etching is set. It can be once. Further, although the electrode substrate 120 of the present embodiment is an example in which the protrusion 122 is formed, when the protrusion 122 is not formed, the number of times of etching can be set to one. The electrode substrate 120 of this embodiment is an example in which the spacers 130 are integrally formed. However, when the spacers 130 are made of different members, the number of etchings can be one. Although a manufacturing method in the case where the spacer 130 is manufactured independently of the movable mirror substrate 110 and the electrode substrate 120 is not illustrated, for example, the spacer 130 can be formed by adjusting the thickness of a silicon (Si) substrate by etching. Furthermore, if necessary, the surface can be thermally oxidized to provide insulation, or a conductive film can be formed on the surface to provide conductivity.

  Hereinafter, a method of forming the micromirror 100 will be described using an electrostatically driven micromirror as an example. In the example of the micromirror 100 according to the embodiment of the present invention shown in FIG. 1, the electrode substrate 120 integrally formed with the spacer 130 illustrated in FIG. 4 and the movable mirror substrate 110 illustrated in FIG. 2 are bonded, bonded, or fastened. Thus, the electrostatic drive type micro mirror 100 is configured. As for the translation position of the movable mirror substrate 110 and the electrode substrate 120 integrally formed with the spacer, for example, an alignment hole (not shown) is formed in both, and a pin or a sphere is inserted into the alignment hole. Thus, the translational position of both can be controlled. As another example, a pattern for alignment (not shown) is formed on the movable mirror substrate 110 and the electrode substrate 120 in which spacers are integrally formed, and the translation position of both is controlled by pattern recognition (for example, image processing). Can do. The height of the movable mirror substrate 110 and the electrode substrate 120 is given by the accuracy of the spacer 130. When forming the electrostatic drive micromirror 100 by bonding, for example, an ultraviolet curable resin can be used as the adhesive. Alternatively, a thermosetting resin can be used. When forming the electrostatically driven micromirror 100 by bonding, for example, gold-tin solder or the like can be used. When the spacer 130 is manufactured independently of the movable mirror substrate 110 and the electrode substrate 120, or when the spacer 130 is formed integrally with the movable mirror substrate 110, the micromirror 100 can be manufactured by the same method.

FIG. 8 shows another embodiment of the micromirror 100 of the present invention. As shown in FIG. 8A, the micromirror 100 of this embodiment is characterized in that the micromirror 100 is housed in a sealable casing 140 and the interior of the casing is filled with optical oil 150. The optical oil 150 filled around the electrostatic drive micromirror 100 functions as a restraining force when an impact is applied to the movable mirror 111, so that the impact resistance of the movable mirror 111 can be improved. FIG. 8 shows an example of the electrostatic drive micromirror 100 having a structure in which the end 118 of the movable mirror 111 is in contact with the electrode substrate 120 during the operation of the movable mirror, but the end 118 of the movable mirror is in contact with the electrode substrate 120. It is not a requirement. The micromirror 100 according to the present embodiment may be driven without moving the end 118 of the movable mirror in contact with the electrode substrate 120.
FIG. 8B is a view of the electrode substrate 120 shown in FIG. 8A viewed from the movable mirror substrate 110 side. The basic configuration is the same as that of the electrode substrate 120 described with reference to FIG. 4, but is characterized in that a resistance wiring 125 is provided in the vicinity where the end portion 118 of the movable mirror 111 contacts. As described above, the micromirror 100 according to the present embodiment may be driven by the end 118 of the movable mirror 111 without contacting the electrode substrate. In the case of a system in which the end 118 of the movable mirror 111 is driven without contacting the electrode substrate, the resistance wiring 125 is not necessary. The resistance wiring 125 is not in contact with the movable mirror 111. When the movable mirror 111 is started to operate, the bubble 151 is generated in the optical oil 150 by energizing the resistance wiring 125 on the side where the end 118 of the movable mirror is approaching. By applying a pushing force to the movable mirror 111 with the bubbles 151, an initial speed is given to the movable mirror 111, the operation of the movable mirror 111 is assisted, and the movable mirror 111 is prevented from sticking. The generation of the bubbles 151 is shown in FIG.

  The configuration based on each of the embodiments described above reduces the mass and moment of inertia of the movable mirror 111 while maintaining the thickness of the portion where the movable mirror 111 functions optically (that is, the portion having the reflective surface 112). Thus, a micromirror excellent in impact resistance and high-speed controllability can be realized while suppressing loss at the optical characteristics, that is, the reflection surface 112.

  Although the above description is about a single-axis rotating electrostatic drive micromirror, the present invention is not limited to a single-axis rotating electrostatic drive micromirror, and can be applied to a multi-axis rotating mirror. FIG. 9 illustrates a cross-sectional view of a biaxially rotated electrostatically driven micromirror. In the configuration shown in FIG. 9, the first beam that supports the movable mirror 111 and provides the rotation shaft 115 is connected to an outer frame portion 160 disposed around the movable mirror 111, and the outer frame portion 160 is The second mirror 162 is connected to the movable mirror substrate 110 in a direction orthogonal to the rotation shaft 115. The relationship between the rotation axis provided by the second beam 162 and the portion having the reflecting surface 112 is the same as in the case of the uniaxial rotation described above.

  FIG. 12 shows an example of an optical switch as an embodiment of the optical component of the present invention. By applying the micromirror of the present invention to an optical component, an optical component excellent in impact resistance and high-speed controllability can be realized while suppressing optical characteristics, that is, loss on the reflecting surface. The micromirror of the present invention is suitable for an optical switch that requires high integration and high-speed controllability. In the embodiment of FIG. 12, a 1 × 2 type optical switch is shown as an example. However, the optical switch of the present invention includes the micromirror of the present invention, one or more input side optical fibers, and the input side optical fibers. An input-side collimating lens, one or more output-side optical fibers, and an output-side collimating lens opposed to the output-side optical fiber, the light beam emitted from the input-side optical fiber being Any configuration may be used as long as the output side optical fiber to which the light beam is recombined is selected by deflecting with a micromirror. In this case, when the input side optical fiber is 1 and the output side optical fiber is 1, an on / off switch is configured.

  FIG. 12A shows a configuration of an optical switch in which the optical fibers 202 are arranged at an angle. The micromirror according to the present invention is used as the light deflection means. Incident light from the optical fiber 202 a is collimated by the collimating lens 204 a and enters the reflecting surface of the movable mirror 111. The optical path 209 is switched by the rotation of the movable mirror 111 to switch the coupling between the optical fibers 202b and 202c. The light reflected by the movable mirror 111 is collimated by the collimating lens 204b or 204c before entering the optical fiber 202b or 202c. Since the optical switch of this configuration uses the micromirror according to the present invention, it is excellent in optical characteristics, impact resistance, and high-speed controllability.

  Further, in the configuration of FIG. 12A, an optical switch that switches coupling of optical fibers as an optical component is shown. However, a photodetector such as a photodiode is disposed instead of a part of the optical fiber to detect the photodetector. May be configured. Or you may comprise the optical device which switches the advancing direction of the light emitted from the laser light source with the micromirror of the present invention and couples it to a desired optical fiber. While the micromirror of the present invention is excellent as a light deflecting means as described above, the application form is not limited, and can be widely applied to optical parts that require the light deflecting means. That is, an optical component can be configured using the micromirror of the present invention as a light deflecting unit.

  In the configuration example of FIG. 12B, a collimating lens array is arranged between the optical fibers 202a, 202b, 202c and the movable mirror 111, and collimating lenses 204a, 204b, 204c are placed on the respective optical fibers. Yes. Here, at least a part of the plurality of optical fibers, for example, in the example of FIG. 12B, collimating lenses 204a and 204c facing the optical fibers 202a and 202c are offset. The offset arrangement means that the optical axis of the optical fiber is shifted from the optical axis of the collimating lens. When the optical axis of the optical fiber is shifted from the optical axis of the collimating lens, the optical axis of the light beam 209 after passing through the collimating lens is deflected in the direction opposite to the direction of shift of the optical fiber. Accordingly, in FIG. 12B, when the optical fiber 202a is shifted in a direction away from the optical fiber 202b with respect to the collimating lens 204a, the optical axis of the light beam 209 is deflected toward the center of the micromirror. As a result, incident light from the optical fiber 202 a is reflected by the reflecting surface of the movable mirror 111. When the reflected light is directed to the collimating lens 204c, the light beam is coupled to the optical fiber 202c by shifting the optical fiber 202c away from the optical fiber 202b with respect to the collimating lens 204c. In this configuration, the number of optical elements can be reduced by eliminating the need for a cylindrical lens while utilizing the characteristics of the electrostatically driven micromirror 100 of the present invention. Further, since the input / output side optical fibers 202 are arranged in parallel, they are easily arranged.

  In the configuration example of FIG. 12C, the fixed mirror 230 is disposed between the collimating lenses 204 a, 204 b, 205 c and the movable mirror 111, and incident light from the optical fiber 202 a is collected on the reflecting surface of the movable mirror 111. The light reflected by the reflecting surface is coupled to the optical fiber 202c. Instead of the offset arrangement of the collimating lens in FIG. 12B, a fixed mirror 230 is used. Further, the input / output side optical fibers 202 are arranged in parallel as in the case of FIG. Since the fixed mirror 230 is an optical component having excellent reflection loss and wavelength-dependent loss, the optical characteristics of the optical switch 200 can be expected to be improved in this configuration. Further, the fixed mirror 230 has an advantage that it is easy to manufacture.

  FIG. 10 shows another example of an optical switch using the micromirror of the present invention. FIG. 10 shows an example of the electrostatic drive type 1-input 2-output optical switch using the uniaxial rotating mirror shown in FIG. 1, but the driving method of the micro mirror 100 is such that the movable mirror 111 is not brought into contact with the electrode substrate 120. By adopting the driving method, it is possible to provide an optical switch with one input and multiple outputs (not shown). For example, a multi-input multi-output optical switch can be configured by using a multi-axis rotating mirror as shown in FIG. 9 for the micro mirror 100 (not shown).

  The optical switch 200 shown in FIG. 10 includes an input port having an input side optical fiber 202a and an input side collimating lens 204a, a cylindrical lens 205, a micro mirror 100, output side collimating lenses 204b and 204c, and output side optical fibers 202b and 202c. 1 is a 1-input 2-output optical switch (1 × 2 optical switch). That is, in the embodiment shown in FIG. 10, a condensing optical system is arranged between the collimating lens and the micromirror instead of the offset arrangement and the fixed mirror shown in FIGS. In this configuration, the light beam is condensed on the reflecting surface. In FIG. 10, a cylindrical lens is used as the condensing optical system.

If the cylindrical lens 205 which is a condensing optical system for condensing the light beam 209 is used for the reflecting surface 112 of the micromirror 100 in the optical switch 200, the reflecting surface 112 of the micromirror 100 can be reduced in size. The reflecting surface 112 can be made smaller by the amount of the condensed light beam 209. This will be described with reference to FIG. A region indicated by D ₀ in FIG. 11 is a light beam diameter on the reflection surface 112 when the condensing optical system is not used. In order to sufficiently cover the region D ₀ , L ₀ is obtained as the length of the reflection surface 112 of the micromirror 100. On the other hand, a hatched area D is the diameter of the light beam on the reflecting surface 112 when a cylindrical lens is used as the condensing optical system. The length L of the reflecting surface 112 required to sufficiently cover the region D is sufficient. As a result, the reflecting surface 112 can be made small, and the mass and moment of inertia of the micromirror 100 can be reduced, so that the impact resistance and high speed controllability are further improved. Note that the cylindrical lens 205 can be replaced with another condensing optical element (lens) as long as the light beam 209 has a property of condensing on the reflecting surface 112.

  The optical switch shown in FIG. 10 will be described in further detail along with its function. The configuration of FIG. 10 has one input side optical fiber 202a and two output side optical fibers 202b and 202c, and the movable mirror 111 is composed of the input side optical fiber 202a and the first output side optical fiber 202b. A first posture that forms an optical path between them and a second posture that forms an optical path between the input-side optical fiber 202a and the second output-side optical fiber 202c can be selected. The optical switch 200 is configured to have a contact point with another member in the second posture and the second posture, and uses a cylindrical lens 205 as a condensing optical system. For example, if the movable mirror 111 is a uniaxial rotation type electrostatic drive mirror shown in FIG. 1, the vicinity of the center of the movable mirror end portion 118 and the mirror electrode portion 113 is in contact with the electrode substrate 120 and the protrusion 122, respectively. The posture or the second posture can be realized. The electrostatically driven micromirror 100 having such a configuration is not only excellent in optical characteristics, impact resistance and high-speed controllability, but also excellent in stability of the operating angle, and thus is effective in improving the optical characteristics of the optical switch. Since the electrostatic drive micromirror 100 having this configuration performs binary digital drive, a 1-input 2-output optical switch (1 × 2 optical switch) can be realized using the electrostatic drive micromirror 100 having the configuration. In the optical switch having the above configuration, the input side optical fiber 202a and the output side optical fibers 202b and 202c can be arranged in a straight line, so that a cylindrical lens can be applied as a condensing optical system.

  FIG. 10A is a diagram showing an optical path formation state from the input side optical fiber 202a to the first output side optical fiber 202c. In FIG. 10A, the movable mirror 111 takes the first posture. FIG. 10B is a diagram showing an optical path forming state from the input side optical fiber 202a to the second output side optical fiber 202b. In FIG. 10B, the movable mirror 111 takes the second posture. FIG. 10C is a diagram showing a state where no driving force is applied to the movable mirror 111.

  An example in which the micromirror according to the present invention is applied to the 1 × 2 optical switch shown in FIG. 10 and the 1 × 2 optical switch is arrayed to form an optical switch array 300 is shown in FIG. The mirror and the optical switch will be described in more detail.

  The optical switch array 300 shown in FIG. 13 includes an optical fiber array 203, a collimating lens array 204, a cylindrical lens 205, and an electrostatically driven micromirror 100 as components. The optical switch array 300 shown in FIG. 13 is an optical switch array in which 8 sets of 1 × 2 optical switches that operate independently are integrated. However, FIG. 13 does not limit the number of 1 × 2 optical switches that can be integrated. Moreover, the application device of the micromirror 100 of this invention is not limited. Each 1 × 2 optical switch element has the structure shown in FIG. The micromirror 100 used in each 1 × 2 optical switch element is the micromirror shown in FIG. The movable mirror 111 determines the operating angle when the vicinity of the center of the mirror end portion 118 and the mirror electrode portion 113 is in contact with the electrode substrate 120 and the protrusion 122. During the switching operation of the optical switch 200, the contact between the movable mirror 111 and the protrusion 122 is temporarily released.

  The optical fiber array 203 includes 24 optical fibers 202 and substrates (optical fiber alignment substrates) 218 and 219 for aligning the fibers as constituent elements. Since the present embodiment integrates eight sets of 1 × 2 optical switches, 24 optical fibers 2 are arranged in three directions in one direction and eight in a direction orthogonal thereto. Here, the three arranged optical fibers correspond to one input optical fiber and two output optical fibers corresponding to one 1 × 2 optical switch. This arrangement direction is defined as a switching direction. An arrangement direction orthogonal to the switching direction is defined as an integration direction. The definitions of the switching direction and the integration direction are described in FIG.

  In this embodiment, the optical fiber pitch in the switching direction is 0.5 mm, and the optical fiber pitch in the integration direction is 1 mm. In the optical fiber array 203, the optical fibers are accurately aligned. In this embodiment, the optical fibers are aligned using an optical fiber alignment substrate 218 having optical fiber alignment holes formed therein. The alignment accuracy of the optical fiber array 203 is given by the accuracy of the optical fiber alignment holes formed in the optical fiber alignment substrate 218.

  In this embodiment, since 8 sets of 1 × 2 optical switches are integrated, three collimating lens arrays 204 are arranged in the switching direction, and a total of 24 collimating lenses arranged in the integration direction are used as constituent elements. Have. Here, the definition of the switching direction and the integration direction conforms to the direction defined by the optical fiber array 203. The pitch of the collimating lens array 204 is made to correspond to the pitch of the optical fiber array 203. In this embodiment, the collimating lens array has a switching direction pitch of 0.5 mm and an integration direction pitch of 1 mm. In this embodiment, the collimating lens array 204 is manufactured by etching a silicon substrate having a substrate thickness of 0.625 mm. An antireflection film corresponding to the wavelength of light to be used (1500 to 1650 nm) is formed on the front and back surfaces of the collimating lens array 204. The collimating lens array 204 has a structure in which a side facing the optical fiber array 203 is a flat surface and a convex lens is formed on the side facing the cylindrical lens 205. Each collimating lens constituting the collimating lens array 204 is a spherical convex lens having a lens diameter of 0.45 mm, and its radius of curvature is 3 mm. The gap between the optical fiber alignment substrate 218 and the collimating lens array 204 is selected so that the light emitted from the input optical fiber becomes a collimated beam having desired characteristics.

  In the present embodiment, one cylindrical lens 205 is shared by eight 1 × 2 optical switches. The cylindrical lens 205 is made of optical glass (BK7), has a radius of curvature of 3.58 mm, and a focal length of 7.15 mm. On the cylindrical lens 205, an antireflection film corresponding to the wavelength (1500 to 1650 nm) of light used on the front and back surfaces is formed. The cylindrical lens 205 is disposed so that the curved surface side faces the collimating lens array 204 and the flat surface side faces the micromirror 110.

  Since this embodiment integrates eight sets of 1 × 2 optical switches, it has eight micromirrors 100 of the present invention. Each micromirror 100 has a uniaxially rotatable structure with a rotation center axis in the arrangement direction of the micromirrors. The arrangement direction of the micromirrors is a direction corresponding to the integration direction of the optical fiber array 203 and the collimating lens array 204. Therefore, the micromirrors 100 are arranged in a line at a pitch corresponding to the pitch in the integration direction of the optical fiber array 203. In this embodiment, the pitch of the micromirrors 100 is 1 mm.

  The movable mirror 111 is supported by a pair of beams 114, which are elastic members, and the beams 114 are connected to a substrate (movable mirror substrate) 110 on which the movable mirror is formed. The beam 114 is composed of a folded beam so that the movable mirror 111 can easily rotate and translate in the Z direction, that is, sink.

  A drive electrode portion 121 for driving the movable mirror 111 is formed on the electrode substrate 120. On the electrode substrate 120, a projection 122 having a thickness of 15 μm is formed. The electrode substrate 120 is manufactured by the method shown in FIG.

  The length of the surface of the movable mirror opposite to the side having the reflecting surface in the direction orthogonal to the rotation center axis is 1735 μm. The movable mirror 111 is operated until it contacts the electrode substrate 120. The movable mirror 111 and the electrode substrate 120 are in contact with the electrode substrate 120 at the mirror end portion 118 and are in contact with the protrusion 122 near the center of the surface opposite to the side having the reflecting surface, thereby realizing an inclination angle of 1 degree. The drive electrode portion 121 is not disposed at a portion where the mirror end portion 118 of the electrode substrate 120 contacts.

  The light emitted from the input-side optical fiber 202a and converted into a collimated beam by the corresponding collimating lens 204a becomes a quasi-elliptical shape having a major axis in the arrangement direction of the movable mirror on the reflecting surface 112 of the movable mirror by the action of the cylindrical lens 205 ( (See FIG. 11). On the reflecting surface 112, the light is 0.2 to 0.25 mm in the major axis direction and 0.1 to 0.15 mm in the minor axis direction, so that the reflecting surface 112 of the movable mirror is 0.4 mm × 0.3 mm. The width of the surface of the movable mirror opposite to the side having the reflecting surface, that is, the length in the direction of the rotation center axis is 0.5 mm. The shape of the thick portion 116 on the reflecting surface side is the shape shown in FIG. The line width of the thick portion 116 is 50 μm. The thickness of the thick portion 116 is made to coincide with the thickness of the portion having the reflecting surface. The thickness matches the thickness of the movable mirror substrate 110.

The movable mirror substrate 110 is made of an SOI having an active layer (Si layer) 173 thickness of 10 μm, an intermediate layer (SiO ₂ layer) 172 thickness of 1 μm, and a base layer (Si layer) 171 thickness of 300 μm, and the method shown in FIG. To make. The thickness of the reflecting surface 112 is 311 μm, which is the same as the initial thickness of the SOI substrate. The thickness of the beam 114 is 10 μm, which is the thickness of the SOI active layer (Si layer). The thickness of the thick portion 116 is 311 μm, the same as the thickness of the reflecting surface 112 portion. The thickness of the thin part 117 of the movable mirror is 10 μm, which is the same as the thickness of the beam 114.

The electrostatic drive micromirror of the present invention has a mass and a moment of inertia of 2.5 × 10 ⁻⁷ [kg] and 6.3 × 10 ⁻¹⁴ [kg · m ² ], respectively. However, the density of silicon (Si) was 2330 [kg / m ³ ]. The mass and moment of inertia of the configuration example in which the entire movable mirror is 311 μm, which is the initial thickness of the SOI substrate, are 6.3 × 10 ⁻⁷ [kg] and 1.8 × 10 ⁻¹³ [kg · m. ² ] is reduced to 0.4 times and 0.35 times, respectively. Therefore, when supported by a beam having the same rigidity, the impact resistance is inversely proportional to the mass and is improved by 2.5 times, and the resonance frequency of the rotational operation is inversely proportional to the square root of the moment of inertia and is improved by 1.7 times. Further, when the entire movable mirror is 10 μm, which is the thickness of the active layer (Si layer), the resistance to warpage is improved to the square of the thickness, that is, 900 times or more. Note that the SOI substrate of this embodiment has a sufficient thickness and is suitable in terms of easy handling. Therefore, the electrostatic drive micromirror of the present invention is an electrostatic drive micromirror excellent in optical characteristics, impact resistance and high-speed controllability. By applying the electrostatic drive micromirror of the present invention, optical characteristics and impact resistance are improved. Provide an optical switch with excellent performance and high-speed control.

It is a figure which shows embodiment of the micromirror of this invention. It is a figure which shows the shape by the side of the reflective surface of the movable mirror board | substrate applied to embodiment of the micromirror of this invention. It is a figure which shows the shape by the side of the reflective surface of the movable mirror applied to embodiment of the micromirror of this invention. It is a figure which shows the shape of the electrode substrate applied to embodiment of the micromirror of this invention. It is a figure which shows the example of a manufacturing method of the movable mirror board | substrate applied to embodiment of the micromirror of this invention. It is a figure which shows embodiment of the micromirror of this invention. It is a figure which shows the example of the preparation methods of the electrode substrate applied to embodiment of the micromirror of this invention. It is a figure which shows embodiment of the micromirror of this invention. It is a figure which shows embodiment of the micromirror of this invention. It is a figure which shows embodiment of the optical switch using the micromirror of this invention. It is a figure which shows the effect of using a condensing optical element in embodiment of the optical switch using the micromirror of this invention. It is a figure which shows embodiment of the optical switch using the micromirror of this invention. It is a figure which shows embodiment of the optical switch array which arrayed the optical switch using the micromirror of this invention. It is a figure which shows the relationship between the ratio of the base | substrate thickness of the part which has a reflective surface, and the thickness of a thin part, and curvature resistance.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100: Micro mirror 110: Movable mirror board | substrate 111: Movable mirror 112: Reflecting surface 113: Mirror electrode part 114: Beam 115: Center axis 116: Thick part 117: Thin part 118: End part 119: Base | substrate 120: Electrode board 121 : Driving electrode part 122: protrusion 123: wiring 124: electrode pad 125: resistance wiring 126: resistance wiring pad 130: spacer 140: housing 150: optical oil 151: bubble 160: outer frame part 162: second beam part 171 : Base layer 172: Intermediate layer 173: Active layer 181: Silicon substrate 200: Optical switch 202, 202 a, 202 b, 202 c: Optical fiber 203: Optical fiber array 204: Collimate lens array 204 a, 204 b, 204 c: Collimate lens 205: Cylindrical Lens 209: Optical path (light beam)
218, 219: Optical fiber alignment substrate 230: Fixed mirror 300: Optical switch array

Claims (11)

A movable mirror having a reflective surface on one surface, a movable mirror substrate to which the movable mirror is coupled, the movable mirror and the movable mirror substrate are coupled, and the movable mirror is rotated with respect to the movable mirror substrate. With a supporting beam,
The reflecting surface is composed of a film formed on the base of the movable mirror,
The base has a thin portion having a thickness smaller than that of the portion having the reflecting surface, and the thin portion has a surface having a height different from the height of the portion having the reflecting surface at least on the surface having the reflecting surface. Having a micromirror. A mirror electrode portion formed on a surface opposite to the surface having the reflective surface, and a drive electrode portion disposed to face the mirror electrode portion,
The micro mirror according to claim 1, wherein the movable mirror is driven by an electrostatic force applied between the drive electrode unit and the mirror electrode unit.   The micromirror according to claim 2, wherein the reflecting surface and the mirror electrode portion are substantially parallel.   2. The movable mirror rotates about the beam as a central axis, the central axis is located at the center in the in-plane direction of the movable mirror, and the reflecting surface straddles the central axis. The micromirror according to any one of?   In the surface side which has the said reflective surface, it has the thick part whose thickness is larger than the said thin part other than the part which has the said reflective surface, The Claims 1-4 characterized by the above-mentioned. The micromirror described.   The micromirror according to claim 5, wherein the thick portion surrounds the portion having the reflective surface in a frame shape with at least a portion sandwiching the thin portion.   The micromirror according to any one of claims 1 to 6, wherein the movable mirror has a maximum thickness in a portion having the reflection surface.   An optical component using the micromirror according to claim 1 as an optical deflection unit. The micromirror according to claim 1, one or more input side optical fibers, an input side collimating lens, one or more output side optical fibers, and an output side collimating lens,
An optical switch that selects an output-side optical fiber to which the light beam is recombined by deflecting the light beam emitted from the input-side optical fiber by the micromirror. The optical switch according to claim 9, wherein a light beam is condensed on a reflection surface of the micromirror using a condensing optical system. The optical switch according to claim 10, wherein
The condensing optical element is a cylindrical lens;
The input side optical fiber is one, the output side optical fiber is two,
A first posture in which the movable mirror forms an optical path between the input-side optical fiber and one of the output-side optical fibers, and the input-side optical fiber and the output-side optical fiber. A second posture that forms an optical path with the other optical fiber of
An optical switch, wherein the movable mirror has a contact point with another member in the first posture and the second posture.

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