JP2011039142A - Optical device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To adjust a tilt angle of a mirror mounted on a movable part with sufficient accuracy in an optical device in which light beam is deflected by making the mirror rock with a static driving mode. <P>SOLUTION: The optical device includes a first protrusion and a second protrusion which are fixed to one member of a substrate and the movable part and which protrude to the other member. The first protrusion has a height in a direction vertical to the substrate higher than that of the second protrusion, and the first protrusion is installed on a position nearer to a rocking shaft of the movable part than a position of the second protrusion. When the movable part is inclined with a maximum tilt angle with respect to the substrate, the first protrusion and the second protrusion are brought into contact with the other member. Thereby the tilt angle of the movable part is adjusted with sufficient accuracy. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an optical device that changes a reflection direction of a light beam by swinging a mirror with an electrostatic force.

  A technique for manufacturing an optical device that deflects a light beam by using a MEMS technique has been developed. This type of optical device includes a substrate, a flexible beam, and a movable portion, and supports the movable portion at a position away from the substrate by the flexible beam. A mirror is installed on the upper surface of the movable part, and the mirror is tilted to a predetermined angle by swinging the movable part with respect to the substrate.

  In an electrostatic drive type optical device that drives this optical device with an electrostatic force, a movable portion formed of a conductor is used as a movable electrode, and a fixed electrode is placed on a substrate at a position facing the movable electrode. When a driving voltage is applied between the movable electrode and the fixed electrode, an electrostatic force acts between the two electrodes. By attracting a part of the movable part toward the substrate side (the lower side of the movable part) by this electrostatic force, the movable part is swung. This electrostatic force is inversely proportional to the square of the distance between the movable electrode and the fixed electrode. By reducing the distance between the movable electrode and the fixed electrode, the electrostatic force for swinging the movable part can be increased. However, when the movable part swings greatly, if the movable electrode installed on the movable part and the fixed electrode installed on the substrate are too close, the movable part is strongly pulled toward the substrate side, and the movable part and the substrate come into contact with each other. End up. This phenomenon is called pull-in.

  A technique for suppressing pull-in has been proposed. For example, Patent Document 1 discloses a technique for preventing the fixed electrode and the movable electrode from contacting each other using a stopper that is fixed to the substrate and protrudes from the substrate toward the movable portion.

JP 2001-13443 A

  In an electrostatic drive type optical device, when an electrostatic attractive force is applied to the movable part to swing the movable part, not only the movable part swings but also the swing axis of the movable part approaches the substrate. Happens. This phenomenon is called subduction. As described in Patent Document 1, when a stopper that protrudes from the substrate toward the movable part is installed, the movable part and the stopper are brought into contact with each other so that the fixed electrode and the movable electrode do not come into contact with each other. I can. However, sinking cannot be prevented.

  When the moving part sinks, the tilt angle of the movable part with respect to the substrate changes depending on the size of the sinking, so that it is difficult to control the mirror to an appropriate tilt angle.

  An object of the present invention is to provide a technique capable of adjusting the tilt angle of a mirror installed in a movable part to be constant.

  An optical device according to the present invention includes a substrate, a support portion fixed to the substrate, a flexible beam extending from the support portion, and a movable portion supported to be swingable with respect to the substrate by the flexible beam. A mirror fixed above the movable portion, a first projection and a second projection fixed to one member of the substrate and the movable portion and projecting toward the other member, and the substrate And a movable electrode provided on the movable part. In this optical device, the first protrusion is higher in the direction perpendicular to the substrate than the second protrusion, and the first protrusion is closer to the swing axis of the movable part than the second protrusion. is set up. When the movable portion is inclined at the maximum inclination angle with respect to the substrate, the first protrusion and the second protrusion are the other members described above (the first protrusion and the second protrusion are directed from the substrate toward the movable portion. When it protrudes, it is a movable part, and it contacts with the other party member below.

  The optical device includes a first protrusion and a second protrusion that are fixed to one member of the substrate and the movable portion and protrude toward the other member. When the movable part is inclined with respect to the substrate, the distance between the upper surface of the substrate and the lower surface of the movable part is relatively large on the side closer to the swing axis, and the distance is relatively small on the side far from the swing axis. Become. In order to cope with this, in the above optical device, a relatively high first protrusion is provided on the side closer to the swing axis, and a relatively low second protrusion on the side far from the swing axis. is set up. For this reason, when a movable part inclines with respect to a board | substrate, the relationship which both a 1st projection part and a 2nd projection part contact | abut on the other party member can be acquired. For example, when the first protrusion and the second protrusion are installed on the substrate, both the first protrusion and the second protrusion can be brought into contact with the movable portion. Further, when the first protrusion and the second protrusion are installed on the movable part, both the first protrusion and the second protrusion can be brought into contact with the substrate. In the optical device described above, the maximum inclination angle at which the movable portion is inclined to the maximum with respect to the substrate is regulated by the first protrusion and the second protrusion being in contact with the counterpart member.

  According to the present invention, the inclination angle of the movable part can be adjusted to the maximum inclination angle by both the first protrusion and the second protrusion being in contact with the mating member. Even if the entire movable portion is about to sink toward the substrate due to the electrostatic force acting between the fixed electrode and the movable electrode, the tilt of the mirror installed on the movable portion is caused by the first protrusion and the second protrusion. The angle is always adjusted to a constant tilt angle. Since it is not necessary to maintain the rigidity of the flexible beam high in order to suppress the occurrence of sinking, the rigidity of the flexible beam should be as low as possible and the movable part can be swung with a low driving voltage. Is possible.

  In the optical device described above, it is preferable that the fixed electrode and the movable electrode face each other at a position between the first protrusion and the second protrusion when observed from the direction along the swing axis. In this case, since the electrostatic force acts between the first protrusion and the second protrusion, both the first protrusion and the second protrusion can be stably brought into contact with the counterpart member.

In the above optical device, it is preferable that the flexible beam has rigidity that does not bend the movable portion when the counterpart member contacts the first protrusion and the second protrusion.
In the above optical apparatus, the movable portion is adjusted to the maximum inclination angle in a state where the movable portion is supported at three points by the first protrusion, the second protrusion, and the flexible beam. When the movable part is supported at three points, the movable part may be deformed in the positional relationship of the three points. If the flexible beam is sufficiently flexible, a relationship in which the movable portion is adjusted to the maximum inclination angle in a state where the movable portion is supported at two points by the first protrusion and the second protrusion can be obtained. When the counterpart member contacts the first protrusion and the second protrusion, if the flexible beam has rigidity (sufficiently flexible rigidity) that does not bend the movable part, the movable part is the first protrusion. And the relationship adjusted to the maximum inclination angle can be obtained in a state where two points are supported by the second protrusion.

  In the above optical device, it is preferable that the first protrusion and the second protrusion are installed at a position where the fixed electrode and the movable part do not contact each other. According to such a configuration, the occurrence of pull-in can be prevented by the first protrusion and the second protrusion.

In the above optical device, the movable part can be configured by a drive part, a connection part, and a mirror installation part. The drive unit is supported by a flexible beam so as to be swingable with respect to the substrate, and a movable electrode is provided. The connecting part is fixed above the driving part. The mirror installation part is fixed to the connection part, is located above the drive part, and the mirror is fixed to the upper surface thereof. The first protrusion and the second protrusion may be fixed to the upper surface of the substrate.
The optical device having this structure can obtain a wide mirror area. Further, the first protrusion and the second protrusion can be formed in the same process as the process of forming the support part, the flexible beam, and the drive part.

  The optical device includes a first step of forming a fixed electrode, a support unit, a flexible beam, a drive unit including a movable electrode, a first projection unit, a second projection unit, and a first sacrificial layer. A second step of forming, a third step of forming a connection portion, a mirror installation portion, a mirror, and a second sacrificial layer; and a fourth step of removing the first sacrificial layer and the second sacrificial layer. It can be manufactured by a manufacturing method.

  According to the present invention, the maximum inclination angle of the movable portion is always managed at a constant angle by the first protrusion and the second protrusion. There is no need to prevent the movable part from sinking, the rigidity of the flexible beam is lowered, and the movable part can be swung with a lower driving voltage.

1 is a perspective view of an optical device according to Example 1. FIG. It is a perspective view which shows the drive part etc. of the optical apparatus of FIG. It is the III-III sectional view taken on the line of FIG. It is a top view which shows the drive part etc. of the optical apparatus of FIG. FIG. 2 schematically illustrates a cross section of the optical device in FIG. 1 and illustrates a state in which a mirror installation portion, a first protrusion, and a second protrusion are in contact with each other. In FIG. 5, it is a figure which shows the relationship between the 1st projection part and the 2nd projection part, and the inclination-angle of a movable part. 6 is a diagram illustrating a manufacturing process of the optical device according to Example 1. FIG. 6 is a diagram illustrating a manufacturing process of the optical device according to Example 1. FIG. 6 is a diagram illustrating a manufacturing process of the optical device according to Example 1. FIG. 6 is a diagram illustrating a manufacturing process of the optical device according to Example 1. FIG. 6 is a diagram illustrating a manufacturing process of the optical device according to Example 1. FIG. 6 is a diagram illustrating a manufacturing process of the optical device according to Example 1. FIG. 6 is a diagram illustrating a manufacturing process of the optical device according to Example 1. FIG. 6 is a diagram illustrating a manufacturing process of the optical device according to Example 1. FIG. 6 is a diagram illustrating a manufacturing process of the optical device according to Example 1. FIG. 6 is a diagram illustrating a manufacturing process of the optical device according to Example 1. FIG. 6 is a diagram illustrating a manufacturing process of the optical device according to Example 1. FIG. 6 is a diagram illustrating a manufacturing process of the optical device according to Example 1. FIG. 6 is a diagram illustrating a manufacturing process of the optical device according to Example 1. FIG. 6 is a diagram illustrating a manufacturing process of the optical device according to Example 1. FIG. 6 is a diagram illustrating a manufacturing process of the optical device according to Example 1. FIG. 6 is a diagram illustrating a manufacturing process of the optical device according to Example 1. FIG. 6 is a diagram illustrating a manufacturing process of the optical device according to Example 1. FIG. 6 is a diagram illustrating a manufacturing process of the optical device according to Example 1. FIG. 6 is a diagram illustrating a manufacturing process of the optical device according to Example 1. FIG. 6 is a diagram illustrating a manufacturing process of the optical device according to Example 1. FIG. It is a perspective view which shows the drive part etc. of the optical apparatus of a modification. It is a figure which shows typically the cross section of the optical apparatus of a modification. It is a figure which shows typically the cross section of the optical apparatus of a modification.

Preferred embodiments according to the present invention are embodied, for example, by examples having the characteristics listed below.
(Characteristic 1) The drive unit, the connection unit, and the mirror installation unit are substantially rigid bodies, and swing as a whole as a whole. That is, the movable part is substantially rigid and swings integrally as a whole.

FIG. 1 is a perspective view of the optical device 100 according to the first embodiment. As shown in FIG. 1, the optical device 100 includes a substrate 101, a pair of supports 102a and 102b formed on the substrate 101, and fixed to the substrate 101, and a pair of supports 102a and 102a. A pair of flexible beams 104a and 104b extending from 102b, a movable portion 103 supported by the pair of flexible beams 104a and 104b, and a mirror 105 fixed to the upper surface of the movable portion 103. ing.
3 is a cross-sectional view taken along line III-III in FIG. As shown in FIG. 3, the movable unit 103 includes a drive unit 107, a connection unit 108, and a mirror installation unit 109. A mirror 105 is fixed on the upper surface of the mirror installation portion 109.
FIG. 2 is a perspective view showing a state in which the mirror installation portion 109 and the mirror 105 are removed from FIG.

  As shown in FIG. 1, the line connecting the connection points of the supports 102a and 102b and the flexible beams 104a and 104b is defined as the x axis, and is orthogonal to the x axis in a plane parallel to the substrate 101. , 102b and flexible beams 104a, 104b passing through the midpoint of the line segment is defined as the y-axis, and the direction orthogonal to the xy plane is defined as the z-axis. When a force in the z-axis direction is applied, the movable portion 103 swings with respect to the substrate 101 with the x-axis as the swing axis. 2 and 3, the x, y, and z axes are set in the same manner as described above, but the description thereof is omitted.

The movable unit 103 includes a drive unit 107, a connection unit 108 fixed above the drive unit 107, and a mirror installation unit 109 fixed above the connection unit 108.
The pair of flexible beams 104 a and 104 b connect the upper ends of the pair of supports 102 a and 102 b and the drive unit 107 constituting the movable unit 103. The pair of flexible beams 104 a and 104 b and the drive unit 107 are supported at a height away from the substrate 101. As shown in FIG. 2, the pair of flexible beams 104a and 104b are folded back many times in order to reduce the rigidity, and the entire length thereof is formed long, so that it can be relatively easily twisted. . Because it is thin and long, it is a movable beam that is easy to twist.

  Each part of the drive part 107, the connection part 108, and the mirror installation part 109, and the connection part which connects them mutually have remarkably high rigidity compared with the flexible beams 104a and 104b. The relative displacement angles of the drive unit 107, the connection unit 108, and the mirror installation unit 109 are significantly smaller than the torsion angles of the flexible beams 104a and 104b. The movable portion 103 is substantially a rigid body, and if the driving portion 107 is inclined by twisting the flexible beams 104a and 104b, the mirror installation portion 109 and the mirror 105 fixed thereto are also inclined by the same angle.

  FIG. 4 is a plan view of the configuration below the drive unit 107 of the optical device 100. As shown in FIGS. 2 and 4, the first protrusions 151a, 151b, 151c, and 151d and the second protrusions 152a, 152b, 152c, and 152d are fixed to the substrate 101 and the supports 102a and 102b. . The first protrusions 151 a to 151 d and the second protrusions 152 a to 152 d protrude toward the mirror installation part 109. The first protrusions 151a to 151d have the same height (the distance in the direction perpendicular to the substrate 101 and equal to the distance in the z-axis direction shown in FIG. 1), and the second protrusions 152a to 152d have the same height. That's it. The first protrusions 151a to 151d are higher in height than the second protrusions 152a to 152d. In the present embodiment, the height of the first protrusions 151 a to 151 d is equal to the height of the upper surface of the driving unit 107 with respect to the upper surface of the substrate 101, and the height of the second protrusions 152 a to 152 d is the height of the substrate 101. It is slightly higher than the height of the lower surface of the drive unit 107 with respect to the upper surface.

  As illustrated in FIG. 4 and the like, the first protrusions 151a to 151d are installed closer to the x-axis than the second protrusions 152a to 152d. That is, the first protrusions 151a to 151d are installed closer to the swing axis of the movable part 103 than the second protrusions 152a to 152d. The first projecting portion 151a and the first projecting portion 151c, and the first projecting portion 151b and the first projecting portion 151d are installed at positions that are symmetric with respect to the x-axis. Further, the first protrusion 151a and the first protrusion 151b, and the first protrusion 151c and the first protrusion 151d are installed at positions that are symmetric with respect to the y-axis. Similarly, the second protrusion 152a and the second protrusion 152c, and the second protrusion 152b and the second protrusion 152d are installed at positions that are symmetric with respect to the x-axis, and the second protrusion 152a and the second protrusion The portion 152b, the second protrusion 152c, and the second protrusion 152d are installed at positions that are symmetric with respect to the y-axis.

  The length of the drive unit 107 in the x-axis and y-axis directions is shorter than the length of the mirror installation unit 109 in the x-axis and y-axis directions. As shown in FIG. 4, the drive unit 107 is H-shaped when viewed from the top. As shown in FIGS. 2 and 4, the first protrusions 151 a to 151 d and the second protrusions 152 a to 152 d are located on the side of the driving unit 107, and the first protrusions 151 a to 151 d and the second protrusion The parts 152a to 152d do not come into contact with the drive unit 107 and restrict the swing of the drive unit 107. On the other hand, as shown in FIG. 1, the mirror installation portion 109 extends to above the first protrusions 151a to 151d and the second protrusions 152a to 152d.

  When observed in the cross section indicated by the line A-A ′ in FIG. 1, the first protrusions 151 a and 151 c and the second protrusions 152 a and 152 c exist below the mirror installation part 109, and the drive part 107 does not exist. When observed in the cross section indicated by the line B-B ′ in FIG. 1, the driving unit 107 exists below the mirror installation unit 109, and the first projecting units 151 a and 151 c and the second projecting units 152 a and 152 c do not exist.

  The optical device 100 is an electrostatic drive type, and the drive unit 107 itself is a conductor and functions as a movable electrode. A pair of fixed electrodes 122 a and 122 b are fixed on the substrate 101 at a position facing the drive unit 107. As shown in FIG. 4, the fixed electrode 122a is disposed at a position farther from the x-axis than the first protrusions 151a and 151b and closer to the x-axis than the second protrusions 152a and 152b. The fixed electrode 122b is disposed at a position farther from the x-axis than the first protrusions 151c and 151d and closer to the x-axis than the second protrusions 152c and 152d. That is, when observed along the swing axis (x axis) of the movable portion 103, the drive portion 107 and the fixed electrode 122a functioning as the movable electrode are located between the first protrusion portions 151a and 151b and the second protrusion portions 152a and 152b. The driving unit 107 that functions as a movable electrode and the fixed electrode 122b are opposed to each other at a position between the first projecting portions 151c and 151d and the second projecting portions 152c and 152d.

  For example, when a movable electrode is grounded and a drive voltage is applied to the fixed electrode 122a using a drive signal generator (not shown), an electrostatic attractive force is generated between the grounded movable electrode and the fixed electrode 122a. The drive unit 107 at a position facing the fixed electrode 122a is sucked toward the substrate 101 side. When a driving voltage is applied to the fixed electrode 122b, an electrostatic attractive force is generated between the grounded movable electrode and the fixed electrode 122b, and the driving unit 107 at a position facing the fixed electrode 122b is attracted to the substrate 101 side. . The flexible beams 104a and 104b have low rigidity, and the drive unit 107 can be swung around the x axis with a low drive voltage. As a result, the drive unit 107 and thus the movable unit 103 can be swung around the x-axis shown in FIG.

  FIG. 5 schematically shows a cross section of the optical device 100 shown in FIG. 3, in which the movable portion 103 swings about the x axis as the swing axis, and the first protrusion 151 a and the second protrusion 152 a The state which contact | abutted to the back surface of the mirror installation part 109 is shown.

  In the optical device 100, the fixed electrode 122a is disposed at a position farther from the swing shaft than the first protrusions 151a and 151b and closer to the swing shaft than the second protrusions 152a and 152b. When a driving voltage is applied between the fixed electrode 122a and the movable electrode, as shown in FIG. 5, the movable portion 103 between the first protrusion 151a and the second protrusion 152a is statically sucked toward the substrate 101. Electric power works.

  FIG. 6 is an enlarged view of a portion where the first protrusion 151 a and the second protrusion 152 a are in contact with the mirror installation portion 109. As shown in FIG. 6, when the mirror installation portion 109 abuts on the first protrusion 151 a and the second protrusion 152 a, the mirror installation portion 109 is inclined with respect to the substrate 101 at an angle θ. In the optical device 100 according to the present embodiment, the angle θ is the maximum inclination angle of the movable portion 103. By adjusting the height and position of the first protrusions 151a to 151d and the second protrusions 152a to 152d, the maximum inclination angle θ of the movable part 103 can be adjusted to a necessary angle. Thereby, the maximum inclination angle θ of the mirror 105 fixed to the movable portion 103 can be adjusted to a necessary angle.

  As a result of the electrostatic force acting on the movable part 103, the entire movable part 103 may approach the substrate 101 and sink. For example, when the movable unit 103 is tilted in the direction shown in FIG. 5, when the sinking occurs, first, the back surface of the mirror installation unit 109 comes into contact with the first protrusions 151 a and 151 b. Thereafter, the movable portion 103 is further inclined while being supported by the first protrusions 151a and 151b from below. The movable portion 103 can increase the inclination angle until the mirror installation portion 109 contacts the second protrusions 152a and 152b. In the optical device 100 according to the present embodiment, even when the movable portion 103 sinks, the rear surface of the mirror installation portion 109 contacts the first protrusions 151a and 151b and the second protrusions 152a and 152b. By tilting the movable portion 103 until it comes into contact, the tilt angle of the movable portion 103 can be adjusted to the maximum tilt angle. Regardless of the size of the sinking of the movable portion 103, the tilt angle of the movable portion 103 can be adjusted to the maximum tilt angle θ.

  In the optical device 100, the pair of flexible beams 104a and 104b are formed long and thin to reduce the rigidity, and can be easily twisted. Therefore, even when the first protrusions 151a and 151b and the mirror installation unit 109 are in contact with each other and a force that attracts the movable unit 103 to the substrate 101 is further applied, the mirror installation unit 109 is not bent and deformed. . Since the pair of flexible beams 104a and 104b is deformed, the mirror installation unit 109 maintains a flat surface. Further, as shown in FIG. 5, even when the movable portion 103 is inclined at the maximum inclination angle, the first projecting portions 151 a to 151 d and the second projection portions 151 a to 151 d are located at positions where the driving portion 107 does not contact the substrate 101. The protrusions 152a to 152d are installed. That is, the first protrusions 151a to 151d and the second protrusions 152a to 152d prevent the pull-in phenomenon from occurring in the optical device 100.

  As described above, in the optical device 100, a driving voltage is applied between the driving unit 107 that functions as a movable electrode and the fixed electrode 122 a installed on the substrate 101, and the movable unit 103 is inclined with respect to the substrate 101. When the first protrusions 151 a and 151 b and the second protrusions 152 a and 152 b are in contact with the back surface of the mirror installation part 109 of the movable part 103, the movable part 103 is inclined with respect to the substrate 101 at the maximum inclination angle θ. It becomes. By applying an electrostatic force that attracts the movable portion 103 toward the substrate 101 until it abuts on the first protrusions 151a and 151b and the second protrusions 152a and 152b, regardless of the size of the sinking of the movable portion 103. The tilt angle of the movable part 103 with respect to the substrate 101 can be adjusted to the maximum tilt angle θ. Similarly, when a driving voltage is applied between the driving unit 107 and the fixed electrode 122b and the movable unit 103 is tilted in the direction opposite to that in FIG. 5, the first projecting portions 151c and 151d and the second projecting portions 152c and 152d are provided. However, by applying an electrostatic force to the movable part 103 until it contacts the back surface of the mirror installation part 109 of the movable part 103, the inclination angle of the movable part 103 with respect to the substrate 101 regardless of the size of the sinking of the movable part 103 Can be adjusted to the maximum inclination angle θ. According to the present embodiment, since it is not necessary to maintain the rigidity of the flexible beam high in order to suppress the occurrence of subduction, the rigidity of the flexible beam is made as low as possible, and the movable part is set with a low driving voltage. It can be made to swing.

Next, a method for manufacturing the optical device 100 will be described with reference to FIGS. 7 to 17 schematically show a cross section of the optical device 100 taken along the line AA ′ of FIG. 1. As shown in FIG. 17, the substrate 101, the first protrusions 151a and 151c, The cross section including the 2nd protrusion part 152a, 152c, the mirror installation part 109, the mirror 105, fixed electrode 122a, 122b, and the flexible beam 104a is shown. In the cross section cut along the line AA ′ in FIG. 1, the drive unit 107 that functions as a movable electrode does not exist.
18 to 26 schematically show a cross section of the optical device 100 taken along the line III-III in FIG. 1, and as shown in FIG. 26, as the substrate 101, the fixed electrodes 122a and 122b, and the movable electrodes, A cross section including the functioning drive unit 107, connection unit 108, mirror installation unit 109, and mirror 105 is shown. In the cross section cut along the line III-III in FIG. 1, the first protrusions 151a to 151d and the second protrusions 152a to 152d are not observed. Also, the flexible beams 104a and 104b are not observed.
FIGS. 10 and 18, FIGS. 11 and 19, FIGS. 12 and 20, FIGS. 13 and 21, FIGS. 14 and 22, FIGS. 15 and 24, FIGS. 16 and 25, FIGS. Sectional drawing in the same timing in a process is shown.

(First step)
In the first step, a layer to be the fixed electrodes 122a and 122b is formed. The first step and the second step will be described with reference to FIGS. 7 to 13 and FIGS. 18 to 21. First, as the material substrate 701, for example, a substrate made of single crystal silicon is prepared. Next, as shown in FIG. 7, thermal oxidation or the like is performed to form an insulating layer 702 made of an oxide film on the surface of the material substrate 701. Next, a polycrystalline silicon layer 703 is formed on the surface of the insulating layer 702. Thereafter, as shown in FIG. 8, photoetching (meaning a series of processes from photolithography to etching such as RIE) is performed, and the polycrystalline silicon layer 703 is patterned. The polycrystalline silicon layer 703 is patterned according to the shape and size of the fixed electrodes 122a and 122b of the optical device 100. Further, thermal oxidation is performed to form an insulating layer 704 on the surface of the polycrystalline silicon layer 703. Thereby, the laminated body shown in FIG. 8 can be obtained.

(Second step)
Next, the second step is performed. In the second step, the support portions 102a and 102b, the flexible beams 104a and 104b, the drive portion 107, the first protrusion portions 151a to 151d, and the second protrusion portions 152a to 152d are formed. In the first half of the second step, the lower portions of the support portions 102a and 102b, the lower portions of the first projecting portions 151a to 151d, the second projecting portions 152a to 152d, and the first sacrificial layer are formed. First, as shown in FIG. 9, after a polycrystalline silicon layer 705 is formed on the surfaces of the insulating layers 702 and 704, photoetching is performed to pattern the polycrystalline silicon layer 705. The polycrystalline silicon layer 705 is formed as a first sacrificial layer, and a part thereof forms the lower portions of the supporting portions 102a and 102b, the lower portions of the first protruding portions 151a to 151d, and the second protruding portions 152a to 152d. Used for. The polycrystalline silicon layer 705 is patterned according to the shapes and sizes of the support portions 102a and 102b, the first protrusions 151a to 151d, and the second protrusions 152a to 152d of the optical device 100. Next, an insulating layer 706 is formed on the surface of the polycrystalline silicon layer 705 by thermal oxidation or the like. Thereby, the laminated body shown in FIG. 10 can be obtained. FIG. 18 shows a cross section taken along line III-III in FIG. 1 at the same timing as FIG. FIG. 18 shows a cut surface in the same plane as the cross section shown in FIG. In FIG. 3, illustration of layers forming each component of the optical device 100 is omitted. The subsequent steps will be described with reference to a diagram showing a cross section taken along line AA ′ in FIG. 1 and a diagram showing a cross section taken along line III-III at the same timing.

  Next, the second half of the second step is performed. In the second half of the second step, the upper portions of the support portions 102a and 102b, the flexible beams 104a and 104b, the drive portion 107, and the upper portions of the first protrusions 151a to 151d are formed. First, as shown in FIGS. 11 and 19, a polycrystalline silicon layer 707 is formed on the surface of the insulating layer 706, and the surface of the polycrystalline silicon layer 707 is planarized by CMP (Chemical Mechanical Polishing) or the like, and then photoetching is performed. The polycrystalline silicon layer 707 is patterned. The portion of the polycrystalline silicon layer 707 exposed on the outermost surface depends on the shape and size of the support portions 102a and 102b, the flexible beams 104a and 104b, the drive portion 107, and the first protrusions 151a to 151d. Patterning. Next, an insulating layer 708 is formed on the surface of the polycrystalline silicon layer 707 by thermal oxidation or the like. Thereby, the laminated body shown in FIGS. 12 and 20 can be obtained.

  Next, a part of the insulating layer 706 is removed by photoetching, and the polycrystalline silicon layers 705 and 707 are partially exposed as shown in FIGS. 13 and 21, the insulating layers 706 and 708 and the polycrystalline silicon layers 705 and 707 surrounded by the insulating layers 706 and 708 are the supporting portions 102a and 102b, the flexible beams 104a and 104b, the driving portion 107, and the first portion of the optical device 100. This is a layer constituting the first protrusions 151a to 151d and the second protrusions 152a to 152d. As shown in FIG. 21, a part of the insulating layer 708 covering the upper surface of the portion that becomes the drive unit 107 is removed, and a part of the polycrystalline silicon layer 707 that becomes the drive unit 107 is exposed.

  As described above, in the second step, the first sacrificial layer, the support portions 102a and 102b, the flexible beams 104a and 104b, the drive portion 107, the first protrusion portions 151a to 151d, and the second protrusion portion 152a. A layer of ~ 152d is formed. In the optical device 100 according to the present embodiment, the uppermost insulating layer of the first protrusions 151a to 151d has the same height as the insulating layer on the upper surface of the driving unit 107, and the uppermost insulating layer of the second protrusions 152a to 152d. The insulating layer has the same height as the insulating layer on the lower surface of the drive unit 107. For this reason, the 1st projection parts 151a-151d and the 2nd projection parts 152a-152d can be manufactured using a 2nd process. The optical device 100 according to the present embodiment does not need to add a process for manufacturing the first protrusions 151a to 151d and the second protrusions 152a to 152d.

(Third step)
In the third step, the connection part 108, the second sacrificial layer, the mirror installation part 109, and the mirror 105 of the optical device 100 are formed. A 3rd process is demonstrated using FIGS. 14-16 and FIGS. 22-25. First, as shown in FIGS. 14 and 22, a polycrystalline silicon layer 709 is formed on the surface of the stacked body in the state of FIGS. 13 and 21, and the surface of the polycrystalline silicon layer 709 is planarized by CMP or the like.

  The polycrystalline silicon layer 709 is formed as a second sacrificial layer, and a part thereof is used for forming the connection portion 108. As shown in FIG. 22, the polycrystalline silicon layer 709 is subjected to photo-etching, and the polycrystalline silicon layer 709 is patterned. Thereafter, thermal oxidation or the like is performed to form an insulating layer 710 made of an oxide film on the surface of the polycrystalline silicon layer 709. Further, part of the insulating layer 710 covering the upper part of the portion used for forming the connection portion 108 in the polycrystalline silicon layer 709 is removed by photoetching. Thereby, the laminated body shown in FIG. 23 can be obtained.

  Next, as shown in FIG. 24, a polycrystalline silicon layer 711 is formed on the surfaces of the polycrystalline silicon layer 709 and the insulating layer 710. Thereafter, photoetching is performed to pattern the polycrystalline silicon layer 711. The polycrystalline silicon layer 711 is patterned according to the shape and size of the mirror installation portion 109 of the optical device 100. Further, after an insulating layer 712 is formed on the surface of the polycrystalline silicon layer 711 by thermal oxidation or the like, a metal layer 713 is formed using a metal such as Al by a method such as sputtering. Photoetching is performed to pattern the metal layer 713 into the shape and size of the mirror 105. Thereby, the laminated body shown in FIG. 24 can be obtained. When the laminated body in the state of FIG. 24 is viewed in a cross section shown in FIG.

  Next, as shown in FIGS. 16 and 25, the insulating layer 710 is photoetched to partially expose the polycrystalline silicon layer 709. The polycrystalline silicon layer 711 surrounded by the insulating layers 710 and 712 becomes the mirror installation portion 109 of the optical device 100.

(4th process)
In the fourth step, the first sacrificial layer and the second sacrificial layer are removed. When the stacked body in the state shown in FIGS. 16 and 25 is subjected to isotropic etching or the like using XeF ₂ gas, portions of the polycrystalline silicon layers 705 and 709 that are not surrounded by the insulating layer are removed. . That is, the first sacrificial layer and the second sacrificial layer are removed. Thus, the optical device 100 shown in FIGS. 17 and 26 can be manufactured. As shown in FIGS. 17 and 26, the uppermost layer of the first protrusions 151 a to 151 d is the same insulating layer 708 as the uppermost layer of the driving unit 107. Therefore, the heights of the first protrusions 151 a to 151 d are equal to the height of the upper surface of the driving unit 107 with respect to the upper surface of the substrate 101. The uppermost layer of the second protrusions 152 a to 152 d is the same insulating layer 706 as the lowermost layer of the driving unit 107.

  According to the above manufacturing method, in the second step of forming the first protrusions 151a to 151d and the second protrusions 152a to 152d, the support portions 102a and 102b, the flexible beams 104a and 104b, and the drive portion 107. Can be formed simultaneously. Since it is not necessary to drastically change the conventional manufacturing process, the optical system including the first protrusions 151a to 151d and the second protrusions 152a to 152d without significantly increasing the labor, cost, and time in the manufacturing process. The device 10 can be manufactured. In the above manufacturing method, the manufacturing method using a single crystal silicon substrate as the material substrate 701 has been described as an example. However, the present invention is not limited to this.

(Modification 1)
The shape, size, and installation position of the first protrusion and the second protrusion are not limited to those described in the above embodiments. For example, as shown in FIG. 27, the second protrusion may be provided at the center in the x-axis direction. In FIG. 27, two second protrusions 252a and 252c are installed at the center of the drive unit 207 in the x-axis direction. The drive unit 207 includes notch portions 270a and 270c whose periphery is cut off along the shape of the second protrusion portions 252a and 252c. Other configurations shown in FIG. 27 are the same as those in FIG. 2, and therefore, the 100th series in FIG. 2 is replaced with the 200th series, and the detailed description thereof is omitted. In FIG. 27, the x, y, and z axes are set in the same manner as the x, y, and z axes described in FIG. 1, but the description thereof is omitted. As in the first embodiment, the first protrusions 251a to 251d and the second protrusions 252a and 252c are inclined to the substrate 201 when the movable part 203 is inclined until the rear surface of the mirror installation part 209 comes into contact therewith. On the other hand, the shape, size, and installation position are adjusted so that the maximum inclination angle is obtained. That is, according to the first modification, the tilt angle of the movable portion 203 relative to the substrate 201 can be adjusted to the maximum tilt angle θ regardless of the size of the sinking of the movable portion 203.

  Furthermore, according to the configuration according to the modification 1, the driving is performed when the movable unit 203 swings with respect to the substrate 201 and the driving unit 207 approaches the substrate 201 side with respect to the upper surfaces of the second protrusions 252a and 252c. The second protrusion 252a or the second protrusion 252c enters the notch 270a or notch 270c of the portion 207. In this state, even if the drive unit 207 attempts to move in the xy plane, the notch 270a or notch 270c of the drive unit 207 contacts the second protrusion 252a or the second protrusion 252c and moves beyond that. Is suppressed. That is, according to the modification shown in FIG. 27, when the movable part 203 swings, it is also possible to obtain an effect that the movable part 203 is prevented from skidding in the xy plane.

(Modification 2)
In the above embodiment, the first protrusion and the second protrusion are fixed to the substrate and extend toward the movable part. Instead of this, the first protrusion and the second protrusion may be fixed to the movable part and may extend toward the substrate. For example, as shown in FIG. 28, the first protrusions 351a and 351c and the second protrusions 352a and 352c are all fixed to the lower surface of the mirror installation part 309 and may extend toward the substrate 301. . The other configuration shown in FIG. 28 is the same as that shown in FIG. 5, and therefore, the 100th series in FIG.

  Also in this case, as in the first embodiment, when the movable portion 303 is tilted until the first protrusion and the second protrusion are in contact with the substrate 301, the movable portion 303 has a maximum inclination angle with respect to the substrate 301. Tilt. The maximum inclination angle can be adjusted to an arbitrary angle by adjusting the shape, size, and installation position of the first protrusion and the second protrusion. For example, as shown in FIG. 29, the movable portion 303 swings with respect to the substrate 301, and the movable portion 303 is inclined until the first protrusion 351a and the second protrusion 352a contact the surface of the substrate 301. Then, the shape, size, and installation position of the first protrusion 351a and the second protrusion 352a are adjusted so that the movable portion 303 has a maximum inclination angle with respect to the substrate 301. When the movable portion 303 is inclined in the direction opposite to that shown in FIG. 29, the movable portion 303 is inclined until the first protruding portion 351c and the second protruding portion 352c contact the substrate 301. The shape, size, and installation position of the first protrusion 351c and the second protrusion 352c are adjusted so that 303 has a maximum inclination angle with respect to the substrate 301. According to the second modification, the tilt angle of the movable portion 303 with respect to the substrate 301 can be adjusted to the maximum tilt angle θ regardless of the size of the sinking of the movable portion 303.

  In the above-described embodiments and modifications, the first protrusion and the second protrusion are designed to contact the back surface of the mirror installation portion. However, even if they are in contact with the back surface of the drive unit, they are movable. The effect that the inclination angle of the movable part with respect to the substrate can be adjusted to the maximum inclination angle θ can be obtained regardless of the size of the sinking of the part. Further, in the above-described embodiments and modifications, the movable part has been described as an example including a drive part, a connection part, and a mirror installation part. However, in the movable part, there is no connection part, and the drive part and the mirror Even if the installation portion is integrated, the same effect can be obtained.

  As mentioned above, although the Example of this invention was described in detail, these are only illustrations and do not limit a claim. The technology described in the claims includes various modifications and changes of the specific examples illustrated above.

  The technical elements described in this specification or the drawings exhibit technical usefulness alone or in various combinations, and are not limited to the combinations described in the claims at the time of filing. In addition, the technology exemplified in this specification or the drawings can achieve a plurality of objects at the same time, and has technical usefulness by achieving one of the objects.

100 Optical device 101, 201, 301 Substrate 102a, 102b, 202a, 202b, 302a, 302b Support body 103, 203, 303 Movable part 104a, 104b, 204a, 204b, 304a, 304b Flexible beam 105, 205, 305 Mirror 107 , 207, 307 Drive unit 108, 208, 308 Connection unit 109 209, 309 Mirror installation unit 151a-151d, 251a-251d, 351a, 351c First projection 152a-152d, 252a-252d, 352a, 352c Second projection 270a, 270c Notch 701 Material substrate 702, 704, 706, 710, 712 Insulating layer 703, 705, 707, 709, 711 Polycrystalline silicon layer 713 Metal layer

Claims (6)

A substrate,
A support fixed to the substrate;
A flexible beam extending from the support,
A movable part supported by the flexible beam so as to be swingable with respect to the substrate;
A mirror fixed to the upper surface of the movable part;
A first protrusion and a second protrusion, which are fixed to one member of the substrate and the movable portion and project toward the other member;
A fixed electrode provided on the substrate;
A movable electrode provided on the movable part,
The first protrusion is higher in height in the direction perpendicular to the substrate than the second protrusion,
The first protrusion is disposed closer to the swing axis of the movable part than the second protrusion;
The optical device, wherein the first protrusion and the second protrusion are in contact with the other member when the movable portion is inclined at a maximum inclination angle with respect to the substrate.   The said fixed electrode and the said movable electrode are facing in the position which exists between a said 1st projection part and a said 2nd projection part when observed along the said rocking | fluctuation axis | shaft. An optical device according to 1.   3. The rigidity according to claim 1, wherein the flexible beam has rigidity that does not bend the movable portion when the other member contacts the first protrusion and the second protrusion. 4. The optical device described.   4. The optical device according to claim 1, wherein the first protrusion and the second protrusion are disposed at a position where the fixed electrode and the movable portion are not brought into contact with each other. 5. . The movable part is
A drive unit that is swingably supported by the flexible beam with respect to the substrate; and the movable electrode is installed;
A connecting part fixed above the drive part;
A mirror installation part fixed to the connection part, located above the drive part, and having the mirror fixed to the upper surface;
5. The optical device according to claim 1, wherein the first protrusion and the second protrusion are both fixed to an upper surface of the substrate. 6. A method for manufacturing an optical device according to claim 5,
A first step of forming the fixed electrode;
A second step of forming the support portion, the flexible beam, the driving portion including the movable electrode, the first protrusion, the second protrusion, and a first sacrificial layer;
A third step of forming the connection portion, the mirror installation portion, the mirror, and a second sacrificial layer;
And a fourth step of removing the first sacrificial layer and the second sacrificial layer.

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