FORM 2
THE PATENTS ACT, 1970
(39 of 1970)
&
THE PATENTS RULES, 2003
COMPLETE SPECIFICATION
[See section 10, Rule 13]
OPTICAL SCANNING DEVICE, DISTANCE MEASURING DEVICE, AND
METHOD FOR MANUFACTURING OPTICAL SCANNING DEVICE;
MITSUBISHI ELECTRIC CORPORATION, A CORPORATION ORGANISED AND
EXISTING UNDER THE LAWS OF JAPAN, WHOSE ADDRESS IS 7-3,
MARUNOUCHI 2-CHOME, CHIYODA-KU, TOKYO 100-8310, JAPAN
THE FOLLOWING SPECIFICATION PARTICULARLY DESCRIBES THE
INVENTION AND THE MANNER IN WHICH IT IS TO BE PERFORMED.
2
DESCRIPTION
TECHNICAL FIELD
[0001] The present disclosure relates to an optical scanning device, a distance
measuring device, and a method for manufacturing an optical scanning device.
5 BACKGROUND ART
[0002] An optical scanning device using a micro electro mechanical systems (MEMS)
technology is known. This optical scanning device is compact and is driven with high
accuracy. The optical scanning device is to scan light emitted to a reflector by
rotating a rotator on which the reflector is superposed about a first torsion beam and a
10 second torsion beam. The rotator, the first torsion beam, and the second torsion beam
include a common active layer. The active layer is made of, for example, silicon (Si).
The active layer is processed by, for example, a semiconductor process such as deep
reactive ion etching (DRIE).
[0003] For example, in Japanese Patent Laying-Open No. 2005-292321 (PTL 1), a
15 planar actuator (optical scanning device) includes a mirror (reflector), a movable plate
(rotator), a torsion bar (first torsion beam and second torsion beam), and a metal film.
The movable plate and the torsion bar have a common active layer silicon (active layer).
The metal film is superposed on the torsion bar.
CITATION LIST
20 PATENT LITERATURE
[0004] PTL 1: Japanese Patent Laying-Open No. 2005-292321
SUMMARY OF INVENTION
TECHNICAL PROBLEM
[0005] In the planar actuator (optical scanning device) disclosed in PTL 1, the metal
25 film is superposed on the torsion bar (first torsion beam and second torsion beam).
This can increase a dimension of the planar actuator of the torsion bar in a thickness
direction and can curb an increase in width dimension of the torsion bar. This in turn
can reduce a hard spring effect of the planar actuator at the position of the torsion bar
and can curb a decrease in maximum deflection angle of the rotator. Note that the
3
hard spring effect is an effect of making a peak frequency higher. Stress generated by
the rotation of the rotator is, however, repeatedly applied to the metal film to cause the
metal film to deteriorate. This may reduce long-term reliability of the planar actuator.
[0006] The present disclosure has been made in view of the above-described problems,
5 and it is therefore an object of the present disclosure to provide an optical scanning
device, a distance measuring device, and a method for manufacturing an optical
scanning device, the optical scanning device being capable of reducing a hard spring
effect at positions of a first torsion beam and a second torsion beam, curbing a decrease
in maximum deflection angle of a rotator, and having high long-term reliability.
10 SOLUTION TO PROBLEM
[0007] An optical scanning device according to the present disclosure includes a
reflector, a rotator, a first torsion beam and a second torsion beam, a first support part, a
second support part, a first elastic layer, and a second elastic layer. The reflector is to
reflect light. The reflector is superposed on the rotator. The rotator is interposed
15 between the first torsion beam and the second torsion beam. The first torsion beam is
interposed between the rotator and the first support part. The second torsion beam is
interposed between the rotator and the second support part. The first elastic layer is
superposed on the first torsion beam. The second elastic layer is superposed on the
second torsion beam. The rotator is rotatable with respect to the first support part and
20 the second support part with the first torsion beam and the second torsion beam as a
rotation axis. The rotator, the first torsion beam, and the second torsion beam include
a common active layer. A vertical dimension of the active layer is smaller than a
horizontal dimension of the active layer in a cross section orthogonal to a direction in
which the rotator is interposed between the first torsion beam and the second torsion
25 beam. A material of the first elastic layer and the second elastic layer is an elastic
material higher in fatigue life higher than metal.
ADVANTAGEOUS EFFECTS OF INVENTION
[0008] In the optical scanning device according to the present disclosure, the first
elastic layer is superposed on the first torsion beam. The second elastic layer is
4
superposed on the second torsion beam. This can reduce the hard spring effect of the
optical scanning device at the positions of the first torsion beam and the second torsion
beam and can curb a decrease in maximum deflection angle of the rotator. Further,
the first elastic layer and the second elastic layer are made of an elastic material higher
5 in fatigue life than metal. It is therefore possible to provide the optical scanning
device having high long-term reliability.
BRIEF DESCRIPTION OF DRAWINGS
[0009] Fig. 1 is a schematic perspective view of a configuration of an optical scanning
device according to a first embodiment.
10 Fig. 2 is a schematic perspective view of the configuration of the optical
scanning device according to the first embodiment.
Fig. 3 is a cross-sectional view taken along a line III-III in Fig. 1.
Fig. 4 is a schematic perspective view of a configuration of an optical scanning
device according to a first modification of the first embodiment.
15 Fig. 5 is a schematic cross-sectional view of a configuration of an optical
scanning device according to a second modification of the first embodiment.
Fig. 6 is a schematic cross-sectional view of the optical scanning device
according to the first embodiment in a preparing step.
Fig. 7 is a schematic cross-sectional view of a substrate on which an elastic
20 material is superposed according to the first embodiment.
Fig. 8 is a schematic cross-sectional view of the optical scanning device
according to the first embodiment in a providing step.
Fig. 9 is a schematic cross-sectional view of the optical scanning device
according to the first embodiment in which coil wiring and the like are disposed.
25 Fig. 10 is a schematic cross-sectional view of the optical scanning device
according to the first embodiment in a laminating step.
Fig. 11 is a graph showing a relationship between a thickness of an active layer
and θ/θ0 and a relationship between the thickness of the active layer and an aspect ratio.
Fig. 12 is a schematic perspective view of a configuration of an optical scanning
5
device according to a second embodiment.
Fig. 13 is a schematic cross-sectional view of the configuration of the optical
scanning device according to the second embodiment.
Fig. 14 is a schematic perspective view of a configuration of an optical scanning
5 device according to a third embodiment.
Fig. 15 is a schematic cross-sectional view of the configuration of the optical
scanning device according to the third embodiment.
Fig. 16 is a schematic cross-sectional view of the optical scanning device
according to the third embodiment in a doping step.
10 Fig. 17 is a schematic cross-sectional view of a substrate on which an elastic
material is superposed according to the third embodiment.
Fig. 18 is a schematic cross-sectional view of the optical scanning device
according to the third embodiment in a providing step.
Fig. 19 is a schematic cross-sectional view of the optical scanning device
15 according to the third embodiment in a laminating step.
Fig. 20 is a schematic perspective view of a configuration of an optical scanning
device according to a fourth embodiment.
Fig. 21 is a schematic plan view of the configuration of the optical scanning
device according to the fourth embodiment.
20 Fig. 22 is a schematic perspective view of a configuration of an optical scanning
device according to a fifth embodiment.
Fig. 23 is a schematic plan view of the configuration of the optical scanning
device according to the fifth embodiment.
Fig. 24 is a block diagram schematically illustrating a configuration of an
25 optical scanning device according to a sixth embodiment.
Fig. 25 is a block diagram schematically illustrating another configuration of
the optical scanning device according to the sixth embodiment.
DESCRIPTION OF EMBODIMENTS
[0010] Hereinafter, embodiments will be described with reference to the drawings.
6
Note that, in the following description, the same or corresponding parts are denoted by
the same reference numerals to avoid the description from being redundant.
[0011] First embodiment
With reference to Figs. 1 to 3, a description will be given of a configuration of
5 an optical scanning device 100 according to a first embodiment. For convenience of
description, a lower insulating film and an upper insulating film are not illustrated in
Fig. 2. As illustrated in Fig. 1, optical scanning device 100 includes a reflector 10, a
rotator 1, a first torsion beam 21 and a second torsion beam 22, a first support part 31, a
second support part 32, a first elastic layer 41, and a second elastic layer 42. In the
10 present embodiment, optical scanning device 100 further includes a magnet M.
Optical scanning device 100 may include first metal wiring 61 and second metal wiring
62.
[0012] Optical scanning device 100 is to scan light. Optical scanning device 100 is,
for example, a micro electro mechanical systems (MEMS) mirror type optical scanning
15 device. Such a MEMS mirror type optical scanning device is applied to, for example,
a distance measuring device, a projector, and the like. Optical scanning device 100 is
formed by, for example, processing a silicon on insulator (SOI) substrate.
[0013] As illustrated in Fig. 1, rotator 1, first torsion beam 21, and second torsion beam
22 include a common active layer LA. A vertical dimension (dimension in a Z-axis
20 direction) of active layer LA is smaller than a horizontal dimension (dimension in a Yaxis direction) of active layer LA in a cross section orthogonal to a direction (X-axis
direction) in which rotator 1 is interposed between first torsion beam 21 and second
torsion beam 22. A ratio of the vertical dimension (dimension in the Z-axis direction)
of active layer LA to the horizontal dimension (dimension in the Y-axis direction) of
25 active layer LA is less than 1. First support part 31 and second support part 32
include active layer LA common to rotator 1, first torsion beam 21, and second torsion
beam 22. Rotator 1, first support part 31, and second support part 32 include a
support layer LS. Rotator 1, first torsion beam 21, second torsion beam 22, first
support part 31, and second support part 32 may include a common surface oxide film
7
LOS, a common intermediate oxide film LOI, a common lower insulating film LI1, and
a common upper insulating film LI2.
[0014] Reflector 10 is to reflect light. Reflector 10 is a metal film. Reflector 10 is
desirably made of metal having a high reflectance at a wavelength of light to be
5 scanned. The light to be scanned is, for example, infrared rays.
[0015] When the light to be scanned is infrared rays, reflector 10 is preferably a gold
(Au) film. When reflector 10 is a gold (Au) film, reflector 10 desirably includes an
adhesion layer (not illustrated). The adhesion layer (not illustrated) adheres to active
layer LA. This may make adhesion between reflector 10 and active layer LA higher.
10 [0016] Reflector 10 including the adhesion layer (not illustrated) is formed by, for
example, laminating a chromium (Cr) film, a nickel (Ni) film, and a gold (Au) film.
Reflector 10 including the adhesion layer (not illustrated) is formed by, for example,
laminating a titanium (Ti) film, a platinum (Pt) film, and a gold (Au) film.
[0017] For example, when optical scanning device 100 is packaged, optical scanning
15 device 100 may be vacuum-encapsulated to make reflector 10 resistant to oxidation.
For example, when optical scanning device 100 is packaged, optical scanning device
100 may be filled with an inert gas such as nitrogen (N2) to make reflector 10 resistant
to oxidation. When reflector 10 is made resistant to oxidation, reflector 10 may be an
aluminum (Al) film.
20 [0018] As illustrated in Fig. 1, reflector 10 is superposed on rotator 1. Rotator 1 is
interposed between first torsion beam 21 and second torsion beam 22. Rotator 1 is
rotatable with respect to first support part 31 and second support part 32 with first
torsion beam 21 and second torsion beam 22 as a rotation axis.
[0019] As illustrated in Fig. 1, in the present embodiment, a direction in which
25 reflector 10 is superposed on rotator 1 is the Z-axis direction. A direction from rotator
1 toward reflector 10 is a Z-axis positive direction. A direction from reflector 10
toward rotator 1 is a Z-axis negative direction. A direction in which rotator 1 is
interposed between first torsion beam 21 and second torsion beam 22 is the X-axis
direction. A direction from first torsion beam 21 toward second torsion beam 22 is an
8
X-axis positive direction. A direction from second torsion beam 22 toward first
torsion beam 21 is an X-axis negative direction. A direction orthogonal to both the Xaxis direction and the Z-axis direction is the Y-axis direction. In the present
embodiment, the X axis, the Y axis, and the Z axis constitute a right-handed system.
5 [0020] As illustrated in Fig. 1, a vertical dimension (dimension in the Z-axis direction)
of first torsion beam 21 of optical scanning device 100 is less than or equal to a
horizontal dimension (dimension in the Y-axis direction) of first torsion beam 21 of
optical scanning device 100 in a cross section orthogonal to a direction (X-axis
direction) in which rotator 1 is interposed between first torsion beam 21 and second
10 torsion beam 22. A vertical dimension (dimension in the Z-axis direction) of second
torsion beam 22 of optical scanning device 100 is less than or equal to a horizontal
dimension (dimension in the Y-axis direction) of second torsion beam 22 of optical
scanning device 100 in a cross section orthogonal to a direction (X-axis direction) in
which rotator 1 is interposed between first torsion beam 21 and second torsion beam 22.
15 [0021] As illustrated in Fig. 2, first elastic layer 41 is superposed on first torsion beam
21. First elastic layer 41 is superposed on first torsion beam 21 from the Z-axis
positive direction. First elastic layer 41 covers at least a part of first torsion beam 21.
First elastic layer 41 extends in the X-axis direction. First elastic layer 41 may be
disposed extending from first support part 31 to rotator 1. In the present embodiment,
20 surface oxide film LOS is interposed between first elastic layer 41 and first torsion
beam 21.
[0022] As illustrated in Fig. 2, second elastic layer 42 is superposed on second torsion
beam 22. Second elastic layer 42 is superposed on second torsion beam 22 from the
Z-axis positive direction. Second elastic layer 42 covers at least a part of second
25 torsion beam 22. Second elastic layer 42 extends in the X-axis direction. Second
elastic layer 42 may be disposed extending from second support part 32 to rotator 1.
In the present embodiment, surface oxide film LOS is interposed between second
elastic layer 42 and second torsion beam 22.
[0023] First elastic layer 41 and second elastic layer 42 are elastic. First elastic layer
9
41 and second elastic layer 42 are higher in fatigue life than metal. In the present
embodiment, the fatigue life is the number of times stress is applied until a material to
which the stress is repeatedly applied is broken. First elastic layer 41 and second
elastic layer 42 may be higher in fatigue life than, for example, aluminum (Al) and an
5 aluminum (Al)-based alloy. The aluminum (Al)-based alloy is, for example, an
aluminum-silicon (Al-Si) alloy. First elastic layer 41 and second elastic layer 42 are
higher in fatigue life than a metal wiring member. Further, first elastic layer 41 and
second elastic layer 42 are higher in elastic limit than metal.
[0024] Even when strain is generated by stress applied to first elastic layer 41 and
10 second elastic layer 42, first elastic layer 41 and second elastic layer 42 are to eliminate
the strain in response to elimination of the stress. That is, even when first elastic layer
41 and second elastic layer 42 become deformed, first elastic layer 41 and second
elastic layer 42 are to return to their original shapes in response to the elimination of
the stress. Note that, when stress exceeding the elastic limit is applied to first elastic
15 layer 41 and second elastic layer 42, first elastic layer 41 and second elastic layer 42 do
not return to their original shapes even if the stress is eliminated.
[0025] As illustrated in Fig. 2, their respective dimensions of first torsion beam 21,
second torsion beam 22, first elastic layer 41, and second elastic layer 42 in the Y-axis
direction are smaller than the dimension of rotator 1 in the Y-axis direction. First
20 torsion beam 21 and first elastic layer 41 serve as a torsion spring. Second torsion
beam 22 and second elastic layer 42 serve as a torsion spring.
[0026] A material of first elastic layer 41 and second elastic layer 42 is an elastic
material higher in fatigue life higher than metal. The material of first elastic layer 41
and second elastic layer 42 contains, for example, silicon (Si). The material of first
25 elastic layer 41 and second elastic layer 42 contains, for example, polysilicon. Note
that, in the present embodiment, polysilicon is polycrystalline silicon. The material of
first elastic layer 41 and second elastic layer 42 contains, for example, monocrystalline
silicon. First elastic layer 41 and second elastic layer 42 may be made of, for example,
a wafer (silicon wafer) made of silicon (Si). The material of first elastic layer 41 and
10
second elastic layer 42 contains, for example, amorphous silicon.
[0027] As illustrated in Fig. 2, first torsion beam 21 is interposed between first support
part 31 and rotator 1. First support part 31 supports first torsion beam 21. Second
torsion beam 22 is interposed between second support part 32 and rotator 1. Second
5 support part 32 supports second torsion beam 22. First support part 31 and second
support part 32 are to not rotate when rotator 1, first torsion beam 21, and second
torsion beam 22 rotate. First support part 31 and second support part 32 are fixed to a
table (not illustrated), for example. The table (not illustrated) is disposed, for example,
in the Z-axis negative direction relative to first support part 31 and second support part
10 32.
[0028] As illustrated in Fig. 2, first metal wiring 61 extends from first support part 31
to rotator 1 via first torsion beam 21. Second metal wiring 62 extends from second
support part 32 to rotator 1 via second torsion beam 22. First metal wiring 61 and
second metal wiring 62 are disposed along upper insulating film LI2 (see Fig. 3).
15 First metal wiring 61 and second metal wiring 62 are made of metal having high
electrical conductivity. Examples of the material of first metal wiring 61 and second
metal wiring 62 include aluminum (Al), aluminum nitride (AlN), and the like.
[0029] As illustrated in Fig. 2, rotator 1 includes coil wiring 5. Coil wiring 5 is
superposed on active layer LA. Coil wiring 5 includes wiring extending in the X-axis
20 direction. Coil wiring 5 has, for example, a spiral shape. First metal wiring 61 and
second metal wiring 62 are electrically connected to coil wiring 5. Coil wiring 5 is
made of metal having high electrical conductivity. Examples of the material of coil
wiring 5 include aluminum (Al), aluminum nitride (AlN), and the like. A current
flowing through coil wiring 5 at least partly flows in the X-axis direction.
25 [0030] As illustrated in Fig. 2, magnet M is disposed apart from rotator 1. Magnet M
is, for example, a permanent magnet. Magnet M includes a first magnet M1 and a
second magnet M2. Rotator 1 is interposed between first magnet M1 and second
magnet M2 with a gap provided between rotator 1, and first magnet M1 and second
magnet M2. Rotator 1 is interposed between first magnet M1 and second magnet M2
11
in the Y-axis direction. A magnetic field generated from magnet M has a magnetic
field in the Y-axis direction. Second magnet M2 is disposed in the Y-axis positive
direction relative to first magnet M1.
[0031] Rotator 1 is to be rotated by Lorentz force, electrostatic force, or the like. In
5 the present embodiment, rotator 1 is to be rotated by Lorentz force generated by the
current flowing through coil wiring 5 and magnetic force generated from magnet M.
When the current flows through coil wiring 5, the current flows in the X-axis direction.
The Lorentz force in the Z-axis direction is generated in coil wiring 5 by the current
flowing through coil wiring 5 in the X-axis direction and the magnetic field generated
10 by magnet M in the Y-axis direction. This causes a force in the Z-axis direction to act
on coil wiring 5 of rotator 1. This generates, in rotator 1, rotational torque about first
torsion beam 21 and second torsion beam 22. This in turn causes rotator 1 to rotate
about first torsion beam 21 and second torsion beam 22 relative to the support parts.
[0032] With reference to Fig. 3, a description will be given below in detail of
15 configurations of active layer LA, support layer LS, and the like according to the first
embodiment.
[0033] As illustrated in Fig. 3, support layer LS, intermediate oxide film LOI, active
layer LA, surface oxide film LOS, lower insulating film LI1, and upper insulating film
LI2 are laminated in this order.
20 [0034] Support layer LS extends in an in-plane direction (along a plane formed by the
X axis and the Y axis). Support layer LS is larger in dimension in the thickness
direction (Z-axis direction) than active layer LA. The material of support layer LS
contains, for example, silicon (Si). Support layer LS includes a first support layer 1S,
a second support layer 31S, and a third support layer 32S. First support layer 1S,
25 second support layer 31S, and third support layer 32S are arranged apart from each
other.
[0035] Intermediate oxide film LOI is directly laminated on support layer LS in the Zaxis direction. The material of intermediate oxide film LOI contains, for example,
silicon (Si). Intermediate oxide film LOI includes a first intermediate oxide film 1OI,
12
a second intermediate oxide film 31OI, and a third intermediate oxide film 32OI.
First intermediate oxide film 1OI, second intermediate oxide film 31OI, and third
intermediate oxide film 32OI are arranged apart from each other.
[0036] Active layer LA is directly laminated on intermediate oxide film LOI in the Z5 axis direction. Active layer LA may be uniform in dimension in the Z-axis direction.
Oxide films are provided on both sides of active layer LA. The material of active
layer LA contains, for example, silicon (Si). The material of active layer LA contains,
for example, monocrystalline silicon. Active layer LA is made of, for example, a
monocrystalline silicon wafer.
10 [0037] Active layer LA includes a first active layer 1A, a second active layer 31A, a
third active layer 32A, a fourth active layer 21A, and a fifth active layer 22A. First
active layer 1A, second active layer 31A, third active layer 32A, fourth active layer
21A, and fifth active layer 22A are integrally formed. First active layer 1A is
interposed between fourth active layer 21A and fifth active layer 22A in the in-plane
15 direction. Fourth active layer 21A is interposed between first active layer 1A and
second active layer 31A in the in-plane direction. Fifth active layer 22A is interposed
between first active layer 1A and third active layer 32A in the in-plane direction.
[0038] Surface oxide film LOS is directly laminated on active layer LA in the Z-axis
direction. Surface oxide film LOS may be uniform in dimension in the Z-axis
20 direction. First elastic layer 41 and second elastic layer 42 are directly laminated on
surface oxide film LOS. The material of surface oxide film LOS contains, for
example, silicon (Si).
[0039] Surface oxide film LOS includes a first surface oxide film 1OS, a second
surface oxide film 31OS, a third surface oxide film 32OS, a fourth surface oxide film
25 21OS, and a fifth surface oxide film 22OS. First surface oxide film 1OS, second
surface oxide film 31OS, third surface oxide film 32OS, fourth surface oxide film
21OS, and fifth surface oxide film 22OS are integrally formed. First surface oxide
film 1OS is interposed between fourth surface oxide film 21OS and fifth surface oxide
film 22OS in the in-plane direction. Fourth surface oxide film 21OS is interposed
13
between first surface oxide film 1OS and second surface oxide film 31OS in the inplane direction. Fifth surface oxide film 22OS is interposed between first surface
oxide film 1OS and third surface oxide film 32OS in the in-plane direction.
[0040] Lower insulating film LI1 is directly laminated on active layer LA, first elastic
5 layer 41, and second elastic layer 42 in the Z-axis direction. Coil wiring 5 is disposed
on lower insulating film LI1. Lower insulating film LI1 is, for example, an oxide film,
an organic film, or the like.
[0041] Lower insulating film LI1 includes a first lower insulating film 1I1, a second
lower insulating film 31I1, a third lower insulating film 32I1, a fourth lower insulating
10 film 21I1, and a fifth lower insulating film 22I1. First lower insulating film 1I1,
second lower insulating film 31I1, third lower insulating film 32I1, fourth lower
insulating film 21I1, and fifth lower insulating film 22I1 are integrally formed. First
lower insulating film 1I1 is interposed between fourth lower insulating film 21I1 and
fifth lower insulating film 22I1 in the in-plane direction. Fourth lower insulating film
15 21I1 is interposed between first lower insulating film 1I1 and second lower insulating
film 31I1 in the in-plane direction. Fifth lower insulating film 22I1 is interposed
between first lower insulating film 1I1 and third lower insulating film 32I1 in the inplane direction.
[0042] Upper insulating film LI2 is directly laminated on lower insulating film LI1 and
20 coil wiring 5. Reflector 10 is disposed on upper insulating film LI2. First metal
wiring 61 and second metal wiring 62 are disposed on upper insulating film LI2. A
distance between upper insulating film LI2 and surface oxide film LOS in the Z-axis
direction may be uniform. Upper insulating film LI2 is, for example, an oxide film,
an organic film, or the like.
25 [0043] Upper insulating film LI2 includes a first upper insulating film 1I2, a second
upper insulating film 31I2, a third upper insulating film 32I2, a fourth upper insulating
film 21I2, and a fifth upper insulating film 22I2. First upper insulating film 1I2,
second upper insulating film 31I2, third upper insulating film 32I2, fourth upper
insulating film 21I2, and fifth upper insulating film 22I2 are integrally formed. First
14
upper insulating film 1I2 is interposed between fourth upper insulating film 21I2 and
fifth upper insulating film 22I2 in the in-plane direction. Fourth upper insulating film
21I2 is interposed between first upper insulating film 1I2 and second upper insulating
film 31I2 in the in-plane direction. Fifth upper insulating film 22I2 is interposed
5 between first upper insulating film 1I2 and third upper insulating film 32I2 in the inplane direction.
[0044] As illustrated in Fig. 3, rotator 1 includes first support layer 1S, first
intermediate oxide film 1OI, first active layer 1A, first surface oxide film 1OS, first
lower insulating film 1I1, and first upper insulating film 1I2. First support layer 1S,
10 first intermediate oxide film 1OI, first active layer 1A, first surface oxide film 1OS,
first lower insulating film 1I1, and first upper insulating film 1I2 are laminated in this
order.
[0045] First torsion beam 21 includes fourth active layer 21A, fourth surface oxide film
21OS, fourth lower insulating film 21I1, and fourth upper insulating film 21I2.
15 Fourth active layer 21A, fourth surface oxide film 21OS, first elastic layer 41, fourth
lower insulating film 21I1, and fourth upper insulating film 21I2 are laminated in this
order.
[0046] Second torsion beam 22 includes fifth active layer 22A, fifth surface oxide film
22OS, fifth lower insulating film 22I1, and fifth upper insulating film 22I2. Fifth
20 active layer 22A, fifth surface oxide film 22OS, second elastic layer 42, fifth lower
insulating film 22I1, and fifth upper insulating film 22I2 are laminated in this order.
[0047] First support part 31 includes second support layer 31S, second intermediate
oxide film 31OI, second active layer 31A, second surface oxide film 31OS, second
lower insulating film 31I1, and second upper insulating film 31I2. Second support
25 layer 31S, second intermediate oxide film 31OI, second active layer 31A, second
surface oxide film 31OS, second lower insulating film 31I1, and second upper
insulating film 31I2 are laminated in this order.
[0048] Second support part 32 includes third support layer 32S, third intermediate
oxide film 32OI, third active layer 32A, third surface oxide film 32OS, third lower
15
insulating film 32I1, and third upper insulating film 32I2. Third support layer 32S,
third intermediate oxide film 32OI, third active layer 32A, third surface oxide film
32OS, third lower insulating film 32I1, and third upper insulating film 32I2 are
laminated in this order.
5 [0049] With reference to Fig. 4, a description will be given below of a configuration of
optical scanning device 100 according to a first modification of the first embodiment.
As illustrated in Fig. 4, rotator 1 includes a recess 11. Recess 11 is open to an
opposite side to reflector 10 (see Fig. 1) with respect to active layer LA. Recess 11 is
open in the Z-axis negative direction. In the present embodiment, recess 11 is
10 provided in support layer LS. In the present embodiment, support layer LS is partially
hollow. Rotator 1 is lighter than rotator 1 having solid support layer LS. Rotator 1
has a rib structure extending in the Z-axis direction. Support layer LS may be smaller
in dimension in the X-axis direction than active layer LA. Support layer LS may be
smaller in dimension in the Y-axis direction than active layer LA.
15 [0050] With reference to Fig. 5, a description will be given below of a configuration of
optical scanning device 100 according to a second modification of the first embodiment.
In the second modification of the first embodiment, lower insulating film LI1 is curved
upward in the Z-axis positive direction by first elastic layer 41 and the second elastic
layer. Upper insulating film LI2 is curved upward in the Z-axis positive direction
20 along the upward curve of lower insulating film LI1. A first lead wiring 71 and a
second lead wiring are disposed along the upward curve of lower insulating film LI1
and the upward curve of upper insulating film LI2. This causes first lead wiring 71
and second lead wiring to deform in the Z-axis positive direction.
[0051] With reference to Figs. 3 and 6 to 10, a description will be given below of a
25 method for manufacturing optical scanning device 100 according to the first
embodiment. The method for manufacturing optical scanning device 100 includes a
preparing step, a providing step, a laminating step, and a forming step.
[0052] As illustrated in Fig. 6, in the preparing step, a substrate SUB is prepared.
Substrate SUB is, for example, a silicon on insulator (SOI) substrate. Substrate SUB
16
includes active layer LA and support layer LS. Substrate SUB may include surface
oxide film LOS and intermediate oxide film LOI. Active layer LA and support layer
LS are laminated. Surface oxide film LOS, active layer LA, intermediate oxide film
LOI, and support layer LS are laminated in this order.
5 [0053] Subsequently, as illustrated in Fig. 7, an elastic layer 4 is provided on an
opposite side to support layer LS with respect to active layer LA of substrate SUB.
Elastic layer 4 is an elastic material higher in fatigue life than metal. Elastic layer 4
contains, for example, silicon (Si) as a material.
[0054] In the present embodiment, elastic layer 4 is formed on surface oxide film LOS.
10 Elastic layer 4 may be formed by, for example, chemical vapor deposition (CVD) or
the like. When elastic layer 4 is a wafer made of silicon (Si), elastic layer 4 may be
bonded onto surface oxide film LOS by, for example, room-temperature activated
bonding, plasma activated bonding, or the like.
[0055] Subsequently, as illustrated in Fig. 8, in the providing step, first elastic layer 41
15 is provided on the opposite side to support layer LS with respect to active layer LA of
substrate SUB. In the providing step, second elastic layer 42 is provided, apart from
first elastic layer 41, on the opposite side to support layer LS with respect to active
layer LA of substrate SUB. First elastic layer 41 is an elastic material higher in
fatigue life than metal. First elastic layer 41 contains, for example, silicon (Si) as a
20 material. Second elastic layer 42 is an elastic material higher in fatigue life higher
than metal. Second elastic layer 42 contains, for example, silicon (Si) as a material.
[0056] In the providing step, specifically, the elastic material is partially removed to
provide first elastic layer 41 and second elastic layer 42. The elastic material is
partially removed, for example, by etching and patterning. The elastic material
25 disposed on surface oxide film LOS may be etched and patterned on surface oxide film
LOS. Shaping the elastic material into a required shape to provide first elastic layer
41 and second elastic layer 42.
[0057] The elastic material may be etched by, for example, wet etching using an
etchant or dry etching such as reactive ion etching (RIE). Etching conditions are
17
selected so as to obtain high selectivity between first elastic layer 41 and second elastic
layer 42, and surface oxide film LOS.
[0058] First elastic layer 41 and second elastic layer 42 may be preferably patterned by
a photolithography technique using a resist film (not illustrated) as a protective film.
5 The resist film (not illustrated) is removed by O2 ashing or the like, for example.
[0059] As illustrated in Fig. 9, lower insulating film LI1 is formed on surface oxide
film LOS, first elastic layer 41, and second elastic layer 42. Upper insulating film LI2
is formed on lower insulating film LI1. Upper insulating film LI2 may be formed on
lower insulating film LI1 by the same method as for lower insulating film LI1.
10 [0060] As illustrated in Fig. 9, coil wiring 5 is disposed on lower insulating film LI1.
Coil wiring 5 is disposed so as to be at least partially exposed from upper insulating
film LI2. Coil wiring 5 is formed on lower insulating film LI1 by sputtering or the
like. Coil wiring 5 thus formed may be etched and patterned. This causes formed
coil wiring 5 to change into a required shape.
15 [0061] Coil wiring 5 disposed on lower insulating film LI1 may be etched by, for
example, wet etching using an etchant or dry etching such as reactive ion etching (RIE).
The etching conditions are selected so as to obtain high selectivity between coil wiring
5 and lower insulating film LI1. Coil wiring 5 may be preferably patterned by a
photolithography technique using a resist film (not illustrated) as a protective film.
20 [0062] First metal wiring 61 and second metal wiring 62 are disposed on upper
insulating film LI2. First metal wiring 61 and second metal wiring 62 are electrically
connected to coil wiring 5. First metal wiring 61 and second metal wiring 62 may be
disposed on upper insulating film LI2 by the same method as for coil wiring 5.
[0063] As illustrated in Fig. 10, in the laminating step, reflector 10 is laminated on
25 active layer LA between first elastic layer 41 and second elastic layer 42. Reflector 10
is to reflect light. Reflector 10 is formed on upper insulating film LI2 by sputtering or
the like. Reflector 10 thus formed may be etched and patterned. This causes formed
reflector 10 to change into a required shape. Reflector 10 disposed on upper
insulating film LI2 may be etched by, for example, wet etching using an etchant or dry
18
etching such as reactive ion etching (RIE). The etching conditions are selected so as
to obtain high selectivity between reflector 10 and upper insulating film LI2.
Reflector 10 may be preferably patterned by a photolithography technique using a resist
film (not illustrated) as a protective film.
5 [0064] Subsequently, as illustrated in Figs. 10 and 3, in the forming step, support layer
LS is removed on an opposite side to first elastic layer 41 with respect to active layer
LA to form first torsion beam 21. In the forming step, support layer LS is removed on
an opposite side to second elastic layer 42 with respect to active layer LA to form
second torsion beam 22. A vertical dimension (dimension in the Z-axis direction) of
10 active layer LA is smaller than a horizontal dimension (dimension in the Y-axis
direction) of active layer LA in a cross section orthogonal to a direction (X-axis
direction) in which rotator 1 is interposed between first torsion beam 21 and second
torsion beam 22. First torsion beam 21 and second torsion beam 22 are formed, and
rotator 1, first support part 31, and second support part 32 are formed accordingly.
15 Rotator 1 is interposed between first torsion beam 21 and second torsion beam 22.
Reflector 10 is superposed on rotator 1.
[0065] Support layer LS is removed by, for example, patterning. Specifically, after
support layer LS is patterned on an opposite side to reflector 10 with respect to active
layer LA, and then intermediate oxide film LOI is patterned. Although not illustrated,
20 surface oxide film LOS and active layer LA may be patterned on an opposite side to
support layer LS with respect to active layer LA. Support layer LS and intermediate
oxide film LOI may be preferably patterned by a photolithography technique using a
resist film (not illustrated) as a protective film.
[0066] Intermediate oxide film LOI may be etched by, for example, wet etching using
25 an etchant or dry etching such as reactive ion etching (RIE). When intermediate oxide
film LOI is etched by RIE, a Cl4 gas is preferably used as an etchant.
[0067] Support layer LS and active layer LA are desirably etched by deep reactive ion
etching (DRIE) using the Bosch process. This allows support layer LS and active
layer LA to be etched with a high aspect ratio. After support layer LS and active layer
19
LA are etched, the resist film is removed. Note that, in the present embodiment, the
aspect ratio is a ratio between an etching depth and an etching width.
[0068] Next, a description will be given of a trade-off between the hard spring effect
and the maximum deflection angle with reference to an optical scanning device
5 according to a comparative example. Note that the hard spring effect is an effect of
making a peak frequency higher. The appearance of the hard spring effect makes it
difficult to control the rotation of rotator 1. The maximum deflection angle is a
maximum angle by which rotator 1 can rotate. This larger the maximum deflection
angle, the more rotator 1 can rotate, so that reflector 10 can reflect light in a wide range.
10 [0069] The hard spring effect (HSE) is caused by tensile stress generated by expansion
and contraction in a longitudinal direction when the beam is twisted, and tends to
become larger as a dimensional ratio between the width of the beam and the thickness
of the beam deviates from 1. It is therefore necessary to avoid a shape having a small
thickness and a large width.
15 [0070] On the other hand, in order to increase the maximum deflection angle of the
rotator, it is necessary to reduce the thickness of the active layer. This is because the
maximum deflection angle is inversely proportional to the moment of inertia of the
rotator. When the active layer is thin, it is necessary to increase the width of the beam
to increase the spring constant, so as to maintain a desired resonance frequency.
20 Therefore, the thinner the beam, the more the aspect ratio of the cross section of the
beam deviates from 1, so that the hard spring effect tends to become larger.
Conversely, when the active layer is increased in thickness, the hard spring effect can
be reduced, but the maximum deflection angle decreases.
[0071] As described above, with the beam having a small thickness and a large width,
25 the intensity of the hard spring effect and the maximum deflection angle are in a tradeoff relationship, and in the MEMS mirror (optical scanning device 100) as in the typical
related art, the deflection angle may be limited by an increase in HSE.
[0072] The optical scanning device according to the comparative example does not
include first elastic layer 41, second elastic layer 42, surface oxide film LOS, lower
20
insulating film LI1, and upper insulating film LI2. The optical scanning device
according to the comparative example is different from optical scanning device 100
according to the first embodiment mainly in that first elastic layer 41 and second elastic
layer 42 are not included.
5 [0073] The optical scanning device according to the comparative example includes
recess 11. The optical scanning device according to the comparative example
includes a surface layer laminated on active layer LA.
[0074] In the present embodiment, a beam thickness is a dimension of first torsion
beam 21 and second torsion beam 22 in the Z-axis direction of optical scanning device
10 100. A beam width is a dimension of first torsion beam 21 and second torsion beam
22 in the Y-axis direction of optical scanning device 100. An aspect ratio is a ratio of
the beam width to the beam thickness (beam width/beam thickness).
[0075] As described above, the hard spring effect is related to the aspect ratio. The
closer the aspect ratio is to 1, the larger the hard spring effect. Since the beam
15 thickness is smaller than the beam width, the aspect ratio is larger than 1. In a range
where the beam thickness is less than or equal to the beam width, the larger the beam
thickness, the closer the aspect ratio is to 1. Therefore, the larger the beam thickness,
the smaller the hard spring effect. Therefore, the larger the beam thickness, the more
the hard spring effect can be reduced.
20 [0076] The relationship between the beam thickness and the maximum deflection angle
is formulated. Subsequently, the relationship between the beam thickness and the
aspect ratio is formulated, and the trade-off relationship between the magnitude of the
maximum deflection angle and the reduction of the hard spring effect is shown. A
resonance frequency fc of rotator 1 is expressed by the following Equation (1).
25 [0077] [Math. 1]

…(1)
[0078] Moment of inertia I0 of rotator 1 is the sum of moment of inertia Ia of active
layer LA and moment of inertia Is of support layer LS. Therefore, moment of inertia
21
I0 of rotator 1 is expressed by the following Equation (2).
[0079] [Math. 2]
…(2)
[0080] Active layer LA is assumed to be a flat plate. Therefore, when the thickness of
5 active layer LA is multiplied by α, moment of inertia I of rotator 1 is expressed by the
following Equation (3).
[0081] [Math. 3]
…(3)
[0082] A torsion spring constant k of first torsion beam 21 and second torsion beam 22
10 when the thickness of active layer LA is multiplied by α is expressed by the following
Equation (4) using Equations (1) and (3).
[0083] [Math. 4]

…(4)
[0084] Torsion spring constant k and maximum deflection angle θ are inversely
15 proportional to each other. Therefore, referring to deflection angle θ0 with α = 1,
maximum deflection angle θ is expressed by the following Equation (5).
[0085] [Math. 5]

…(5)
[0086] Torsion spring constant k is expressed by the following Equation (6) using
20 Young's modulus E and the Poisson's ratio γ. Note that a in Equation (6) is expressed
by the following Equation (7).
[0087] [Math. 6]
22

…(6)
[0088] [Math. 7]

…(7)
[0089] From Equations (4) and (6), a beam width w when a beam thickness t = α * t0 is
5 expressed by the following Equation (8) when beam thickness t is smaller than beam
width w.
[0090] [Math. 8]

…(8)
[0091] From Equation (8), a ratio between beam width w and beam thickness t is
10 expressed by the following Equation (9).
[0092] [Math. 9]

…(9)
[0093] As shown in Equations (5) and (9), when the ratio of moment of inertia Ia of
active layer LA to total moment I of rotator 1 is high, the maximum deflection angle
15 and the aspect ratio greatly change in a manner that depends on a change in the
thickness of active layer LA.
[0094] Subsequently, with reference to a first comparative example and a second
comparative example, changes in the maximum deflection angle and the aspect ratio
caused by a change in the thickness of active layer LA are calculated. Table 1 shows
20 parameters of the first comparative example and the second comparative example.
[0095] [Table 1]
Parameter First comparative example Second comparative example
23
Density of silicon 2331 kg/m3
Width of rotator 2500 μm
Length of rotator 2500 μm
Thickness of support layer 200 μm
Rib width 20 μm
α 1 1.33
Thickness of active layer 15 μm 20 μm
Beam width 500 μm 276 μm
[0096] In the first comparative example and the second comparative example, the
density of silicon (Si) is 2331 (kg/m3). The width of rotator 1 is 2500 μm. The
length of rotator 1 is 2500 μm. A rib width D (see Fig. 12) is 20 μm. The thickness
5 of support layer LS is 200 μm.
[0097] In the first comparative example, α is 1. The thickness of active layer LA is 15
μm. The beam width is 500 μm. The aspect ratio is 33.3. In the second
comparative example, α is 1.33. The thickness of active layer LA is 20 μm. The
beam width is 276 μm. The aspect ratio is 13.8.
10 [0098] In the first comparative example and the second comparative example, the
moment of inertia was calculated on the basis of the above-described dimensions and
the like. As α changes, the thickness of active layer LA and beam width change. As
α increases, the thickness of active layer LA increases.
[0099] Fig. 11 is a graph showing the relationship between the thickness of active layer
15 LA and θ/θ0 using a first axis on the left side of Fig. 11, and the relationship between
the thickness of active layer LA and the aspect ratio using a second axis on the right
side of Fig. 11. As shown in Fig. 11, in a range where the beam width is larger than
the beam thickness (a range where the aspect ratio is larger than 1), the larger the
maximum deflection angle, the larger the aspect ratio. Therefore, the larger the
20 maximum deflection angle, the more the hard spring effect is likely to appear.
Therefore, the magnitude of the maximum deflection angle and the reduction of the
hard spring effect are in a trade-off relationship.
[0100] In the second comparative example, α is larger than in the first comparative
24
example. The aspect ratio is smaller than in the first comparative example. The
aspect ratio is closer to 1 than in the first comparative example. Therefore, in the
second comparative example, the appearance of the hard spring effect can be reduced
as compared with the first comparative example. In the second comparative example,
5 however, the maximum deflection angle is smaller than in the first comparative
example by at least 20%.
[0101] Therefore, in order to curb a decrease in the maximum deflection angle and to
reduce the appearance of the hard spring effect, it is necessary to curb an increase in the
thickness of first active layer 1A of rotator 1 and to increase the dimension (beam
10 thickness) of first torsion beam 21 and second torsion beam 22 of optical scanning
device 100.
[0102] In the present embodiment, since the thickness of active layer LA is not
changed, α = 1 is satisfied, and thus, moment of inertia I of rotator 1 is I = I0 from
Equations (2) and (3). Therefore, according to Equation (5), the maximum deflection
15 angle is θ = θ0.
[0103] Further, the aspect ratio (beam width/beam thickness) when only the beam
thickness is multiplied by α using first elastic layer 41 and second elastic layer 42
without changing moment of inertia I0 of the rotator is expressed by the following
Equation (10).
20 [0104] [Math. 10]

…(10)
[0105] As shown in Equation (10), the larger α (beam thickness), the smaller the aspect
ratio (beam width/beam thickness). That is, the aspect ratio (beam width/beam
thickness) becomes close to 1.
25 [0106] Next, actions and effects of the present embodiment will be described.
In optical scanning device 100 according to the first embodiment, as illustrated
in Fig. 1, optical scanning device 100 includes first elastic layer 41 and second elastic
25
layer 42. First elastic layer 41 is superposed on first torsion beam 21. Second elastic
layer 42 is superposed on second torsion beam 22. This allows an increase in
dimension of first torsion beam 21 and second torsion beam 22 of optical scanning
device 100 in the thickness direction (Z-axis direction). The vertical (Z-axis
5 direction) dimension of active layer LA is smaller than the horizontal (Y-axis direction)
dimension of active layer LA. This makes the aspect ratio of first torsion beam 21 and
second torsion beam 22 close to 1 as compared with a case where first elastic layer 41
and second elastic layer 42 are not disposed. This can reduce the hard spring effect of
optical scanning device 100 at the positions of first torsion beam 21 and second torsion
10 beam 22 as compared with the case where first elastic layer 41 and second elastic layer
42 are not disposed.
[0107] As illustrated in Fig. 1, first elastic layer 41 is superposed on first torsion beam
21. Second elastic layer 42 is superposed on second torsion beam 22. This increases
the dimension of first torsion beam 21 and second torsion beam 22 of optical scanning
15 device 100 in the thickness direction (Z-axis direction) and curbs an increase in the
dimension of active layer LA in the thickness direction (Z-axis direction). This in turn
curbs an increase in the dimension of active layer LA of rotator 1 in the thickness
direction (Z-axis direction). It is therefore possible to curb a decrease in the
maximum deflection angle of rotator 1. As a result, it is possible to achieve both a
20 reduction in the hard spring effect of optical scanning device 100 at the positions of
first torsion beam 21 and second torsion beam 22 and a decrease in the maximum
deflection angle of rotator 1.
[0108] As illustrated in Fig. 1, first elastic layer 41 and second elastic layer 42 are each
an elastic material higher in fatigue life higher than metal. This makes first elastic
25 layer 41 and second elastic layer 42 less susceptible to deterioration even when the
rotation of rotator 1 repeatedly applies stress to first elastic layer 41 and second elastic
layer 42. Specifically, it is possible to make first elastic layer 41 and second elastic
layer 42 less susceptible to deterioration than a case where the material of first elastic
layer 41 and second elastic layer 42 is metal. It is therefore possible to provide optical
26
scanning device 100 having high long-term reliability.
[0109] As illustrated in Fig. 2, optical scanning device 100 includes magnet M.
Rotator 1 includes coil wiring 5. Rotator 1 is to be rotated by Lorentz force generated
by the current flowing through coil wiring 5 and magnetic force generated from magnet
5 M. This allows rotator 1 to rotate. This allows reflector 10 superposed on rotator 1
to rotate. This in turn allows reflector 10 to reflect light at a desired reflection angle.
[0110] As illustrated in Fig. 2, the material of first elastic layer 41 and second elastic
layer 42 contains silicon (Si). Silicon (Si) is higher in fatigue life than metal. This
makes first elastic layer 41 and second elastic layer 42 higher in fatigue life than metal.
10 This in turn can make first elastic layer 41 and second elastic layer 42 less susceptible
to deterioration than a case where the material of first elastic layer 41 and second
elastic layer 42 contains metal.
[0111] As illustrated in Fig. 2, the material of first elastic layer 41 and second elastic
layer 42 contains polysilicon. Polysilicon is higher in fatigue life than metal. This
15 makes first elastic layer 41 and second elastic layer 42 higher in fatigue life than metal.
This in turn can make first elastic layer 41 and second elastic layer 42 less susceptible
to deterioration than a case where the material of first elastic layer 41 and second
elastic layer 42 contains metal.
[0112] As illustrated in Fig. 2, the material of first elastic layer 41 and second elastic
20 layer 42 contains monocrystalline silicon (Si). Monocrystalline silicon (Si) is higher
in fatigue life than metal. This makes first elastic layer 41 and second elastic layer 42
higher in fatigue life than metal. This in turn can make first elastic layer 41 and
second elastic layer 42 less susceptible to deterioration than a case where the material
of first elastic layer 41 and second elastic layer 42 contains metal.
25 [0113] As illustrated in Fig. 2, the material of first elastic layer 41 and second elastic
layer 42 contains monocrystalline silicon (Si). Therefore, first elastic layer 41 and
second elastic layer 42 are made of, for example, a monocrystalline silicon wafer.
The thickness of the monocrystalline silicon wafer can be controlled more easily than
the thickness of polysilicon. Specifically, when first elastic layer 41 and second
27
elastic layer 42 are made of polysilicon, the thicknesses of first elastic layer 41 and
second elastic layer 42 is controlled on the basis of a time taken for forming first elastic
layer 41 and second elastic layer 42 on surface oxide film LOS. When first elastic
layer 41 and second elastic layer 42 are made of a monocrystalline silicon wafer, the
5 thickness of the monocrystalline silicon wafer can be controlled in advance during
manufacture of the monocrystalline silicon wafer. This makes the control of the
thicknesses of first elastic layer 41 and second elastic layer 42 easy as compared with a
case where first elastic layer 41 and second elastic layer 42 contain polysilicon.
[0114] In optical scanning device 100 according to the first modification of the first
10 embodiment, as illustrated in Fig. 4, rotator 1 includes recess 11. This makes rotator 1
according to the present embodiment lighter than solid rotator 1. This makes the
moment of inertia of rotator 1 according to the present embodiment smaller than the
moment of inertia of solid rotator 1. This in turn allows an increase in the maximum
deflection angle.
15 [0115] In the first modification of the first embodiment, the ratio of the moment of
inertia of active layer LA to the moment of inertia of entire rotator 1 is higher than a
corresponding ratio for solid rotator 1. Therefore, if the dimension of active layer LA
in the thickness direction (Z-axis direction) increases, the maximum deflection angle
decreases as compared with solid rotator 1. In optical scanning device 100 according
20 to the present disclosure, since first elastic layer 41 and second elastic layer 42 are
superposed on second active layer 31A, it is possible to curb an increase in the
dimension of active layer LA in the thickness direction (Z-axis direction). Therefore,
in optical scanning device 100 according to the present disclosure, even when rotator 1
includes recess 11, it is possible to curb a decrease in the maximum deflection angle.
25 [0116] In optical scanning device 100 according to the second modification of the first
embodiment, as illustrated in Fig. 5, lower insulating film LI1 is curved upward along
first elastic layer 41 and the second elastic layer. This eliminates the need of making
the distance between the upper surface of lower insulating film LI1 and surface oxide
film LOS uniform. It is therefore possible to easily process lower insulating film LI1.
28
[0117] The method for manufacturing optical scanning device 100 according to the
first embodiment includes the providing step. As illustrated in Fig. 8, in the providing
step, first elastic layer 41 is provided on the opposite side to support layer LS with
respect to active layer LA of substrate SUB. In the providing step, second elastic
5 layer 42 is provided, apart from first elastic layer 41, on the opposite side to support
layer LS with respect to active layer LA of substrate SUB. As illustrated in Figs. 8
and 3, this increases the dimension of first torsion beam 21 and second torsion beam 22
of optical scanning device 100 in the thickness direction (Z-axis direction) and curbs an
increase in the dimension of active layer LA in the thickness direction (Z-axis
10 direction). It is therefore possible to reduce the hard spring effect and to curb a
decrease in the maximum deflection angle of rotator 1.
[0118] As illustrated in Fig. 8, in the providing step, first elastic layer 41 is provided on
the opposite side to support layer LS with respect to active layer LA of substrate SUB.
In the providing step, second elastic layer 42 is provided, apart from first elastic layer
15 41, on the opposite side to support layer LS with respect to active layer LA of substrate
SUB. First elastic layer 41 is an elastic material higher in fatigue life than metal.
Second elastic layer 42 is an elastic material higher in fatigue life higher than metal.
It is therefore possible to provide optical scanning device 100 having high long-term
reliability.
20 [0119] Second embodiment
With reference to Figs. 12 and 13, a description will be given below of a
configuration of an optical scanning device 100 according to a second embodiment.
The second embodiment is the same in configuration, manufacturing method, and
actions and effects as the first embodiment unless otherwise specified. Therefore, the
25 same components as the components according to the first embodiment are denoted by
the same reference numerals to avoid the description from being redundant.
[0120] As illustrated in Fig. 12, optical scanning device 100 includes a first lead wiring
71 and a second lead wiring 72. First lead wiring 71 is disposed on first support part
31. Second lead wiring 72 is disposed on second support part 32. Rotator 1
29
according to the present embodiment may include recess 11 (see Fig. 4).
[0121] A material of first lead wiring 71 and second lead wiring 72 is metal having
high electrical conductivity. Examples of the material of first lead wiring 71 and
second lead wiring 72 include aluminum (Al), aluminum nitride (AlN), and the like.
5 First lead wiring 71 extends toward but does not reach first torsion beam 21. Second
lead wiring 72 extends toward but does not reach second torsion beam 22.
[0122] As illustrated in Fig. 13, first elastic layer 41 includes a first diffusion wiring
part 41D. First diffusion wiring part 41D extends from first support part 31 to rotator
1. Second elastic layer 42 includes first diffusion wiring part 41D. Second diffusion
10 wiring part 42D extends from second support part 32 to rotator 1.
[0123] First diffusion wiring part 41D of first elastic layer 41 and second diffusion
wiring part 42D of second elastic layer 42 are higher in elastic limit than first metal
wiring 61 and second metal wiring 62. A material of first diffusion wiring part 41D
and second diffusion wiring part 42D contains silicon (Si).
15 [0124] First diffusion wiring part 41D is doped with an impurity. Second diffusion
wiring part 42D is doped with an impurity. This makes first diffusion wiring part 41D
and second diffusion wiring part 42D electrically conductive. First diffusion wiring
part 41D and second diffusion wiring part 42D serve as wiring. First lead wiring 71 is
electrically connected to second lead wiring 72 via first diffusion wiring part 41D, coil
20 wiring 5, and second diffusion wiring part 42D.
[0125] Examples of the impurity include boron (B) and phosphorus (P). First elastic
layer 41 and second elastic layer 42 are doped with the impurity at a high dopant
density. Note that, in the present embodiment, the dopant density is density of the
impurity used for doping. The dopant density is, for example, 1 * 1020 (cm3).
25 [0126] Next, actions and effects of the present embodiment will be described.
In optical scanning device 100 according to the second embodiment, as
illustrated in Fig. 13, first elastic layer 41 includes first diffusion wiring part 41D.
Second elastic layer 42 includes second diffusion wiring part 42D. If stress applied to
the beam wiring (first diffusion wiring part 41D and second diffusion wiring part 42D,
30
or first metal wiring 61 and second metal wiring 62) is larger than the elastic limit of
the beam wiring, the beam wiring may deteriorate. It is therefore necessary to make
stress applied to the beam wiring lower than the elastic limit of the beam wiring. The
larger the maximum deflection angle, the larger the stress applied to the beam wiring.
5 Therefore, as the elastic limit of the beam wiring becomes higher, the maximum
deflection angle can be made larger. First diffusion wiring part 41D and second
diffusion wiring part 42D are higher in elastic limit than first metal wiring 61 and
second metal wiring 62. This allows optical scanning device 100 according to the
present embodiment to obtain a large deflection angle as compared with the case where
10 first metal wiring 61 and second metal wiring 62 are provided as the beam wiring.
[0127] As illustrated in Fig. 13, as illustrated in Fig. 13, first elastic layer 41 includes
first diffusion wiring part 41D. Second elastic layer 42 includes second diffusion
wiring part 42D. First diffusion wiring part 41D and second diffusion wiring part 42D
are higher in elastic limit than first metal wiring 61 and second metal wiring 62. This
15 can make, even when the maximum deflection angle is large, the beam wiring less
susceptible to deterioration. It is therefore possible to provide optical scanning device
100 that is higher in long-term reliability than optical scanning device 100 including
first metal wiring 61 and second metal wiring 62.
[0128] As illustrated in Fig. 12, first lead wiring 71 extends toward but does not reach
20 first torsion beam 21. Second lead wiring 72 extends toward but does not reach
second torsion beam 22. This prevents first lead wiring 71 and second lead wiring 72
from rotating even when rotator 1 rotates together with first torsion beam 21 and
second torsion beam 22. This can make first lead wiring 71 and second lead wiring 72
less susceptible to deterioration.
25 [0129] As illustrated in Fig. 13, first lead wiring 71 is electrically connected to second
lead wiring 72 via first diffusion wiring part 41D, coil wiring 5, and second diffusion
wiring part 42D. This can prevent each of the first metal wiring and the second metal
wiring from being deformed along the upward curve of a corresponding one of first
elastic layer 41 and second elastic layer (see Fig. 5). This in turn can prevent the
31
wiring from being broken. In particular, it is effective in optical scanning device 100
in which first elastic layer 41 and second elastic layer 42 have large dimensions in the
thickness direction.
[0130] Third embodiment
5 With reference to Figs. 14 and 15, a description will be given below of a
configuration of an optical scanning device 100 according to a third embodiment. The
third embodiment is the same in configuration, manufacturing method, and actions and
effects as the first embodiment unless otherwise specified. Therefore, the same
components as the components according to the first embodiment are denoted by the
10 same reference numerals to avoid the description from being redundant.
[0131] According to the present embodiment, as illustrated in Fig. 14, optical scanning
device 100 includes first lead wiring 71 and second lead wiring 72. First lead wiring
71 is disposed on first support part 31. Second lead wiring 72 is disposed on second
support part 32. Rotator 1 according to the present embodiment may include recess
15 11 (see Fig. 4).
[0132] As illustrated in Fig. 15, active layer LA includes a diffusion wiring part LAD.
The diffusion wiring part is doped with an impurity. The dopant density is, for
example, 1 * 1020 (cm3). This causes the diffusion wiring part to serve as wiring.
First lead wiring 71 is electrically connected to second lead wiring 72 via diffusion
20 wiring part LAD and coil wiring 5.
[0133] As illustrated in Fig. 15, diffusion wiring part LAD includes a third diffusion
wiring part LAD1 and a fourth diffusion wiring part LAD2. Third diffusion wiring
part LAD1 is electrically connected to first lead wiring 71 and coil wiring 5. Third
diffusion wiring part LAD1 extends from first support part 31 to rotator 1. Fourth
25 diffusion wiring part LAD2 is electrically connected to second lead wiring 72 and coil
wiring 5. Fourth diffusion wiring part LAD2 extends from second support part 32 to
rotator 1.
[0134] The material of active layer LA contains silicon (Si). This makes diffusion
wiring part LAD higher in elastic limit than first metal wiring 61 and second metal
32
wiring 62.
[0135] With reference to Figs. 15 to 19, a description will be given below of a method
for manufacturing optical scanning device 100 according to the third embodiment.
The method for manufacturing optical scanning device 100 according to the present
5 embodiment includes a preparing step, a doping step, a providing step, a laminating
step, and a forming step.
[0136] As illustrated in Fig. 16, in the preparing step, substrate SUB is prepared.
Active layer LA of substrate SUB contains silicon (Si) as a material. Subsequently, as
illustrated in Fig. 16, in the doping step, active layer LA is doped with an impurity.
10 As a result, diffusion wiring part LAD is formed in active layer LA.
[0137] Subsequently, as illustrated in Fig. 17, a silicon substrate is bonded to an
opposite side to support layer LS with respect to active layer LA. For the bonding, for
example, surface-activated bonding and room-temperature activated bonding are used.
The silicon substrate includes elastic layer 4 and surface oxide film LOS. In the
15 present embodiment, elastic layer 4 is, for example, monocrystalline silicon (Si).
Surface oxide film LOS is provided on a surface of elastic layer 4. Surface oxide film
LOS is desirably a thermal oxide film high in flatness. Surface oxide film LOS is
interposed between elastic layer 4 and active layer LA.
[0138] Subsequently, as illustrated in Fig. 18, in the providing step, first elastic layer
20 41 and second elastic layer 42 are provided. Elastic layer 4 (see Fig. 17) is partially
removed to provide first elastic layer 41 and second elastic layer 42. Elastic layer 4
(see Fig. 17) is partially removed by patterning by, for example, deep reactive ion
etching (DRIE) or the like.
[0139] Subsequently, as illustrated in Fig. 19, in the laminating step, reflector 10 is
25 laminated on active layer LA.
[0140] Subsequently, as illustrated in Figs. 19 and 15, in the forming step, first torsion
beam 21, second torsion beam 22, rotator 1, first support part 31, and second support
part 32 are formed.
[0141] Next, actions and effects of the present embodiment will be described.
33
In optical scanning device 100 according to the third embodiment, as illustrated
in Fig. 15, active layer LA includes diffusion wiring part LAD. Diffusion wiring part
LAD is higher in elastic limit than first metal wiring 61 and second metal wiring 62.
This allows optical scanning device 100 according to the present embodiment to obtain
5 a large maximum deflection angle as compared with the case where first metal wiring
61 and second metal wiring 62 are provided as the beam wiring (diffusion wiring part
LAD, or first metal wiring 61 and second metal wiring).
[0142] As illustrated in Fig. 15, active layer LA includes diffusion wiring part LAD.
Diffusion wiring ALD is higher in elastic limit than first metal wiring 61 and second
10 metal wiring 62. This can make, even when the maximum deflection angle is large,
the beam wiring less susceptible to deterioration. It is therefore possible to provide
optical scanning device 100 that is higher in long-term reliability than optical scanning
device 100 including first metal wiring 61 and second metal wiring 62.
[0143] As illustrated in Fig. 15, first lead wiring 71 extends toward but does not reach
15 first torsion beam 21. Second lead wiring 72 extends toward but does not reach
second torsion beam 22. This prevents first lead wiring 71 and second lead wiring 72
from rotating even when rotator 1 rotates together with first torsion beam 21 and
second torsion beam 22. This can make first lead wiring 71 and second lead wiring 72
less susceptible to deterioration.
20 [0144] As illustrated in Fig. 15, first lead wiring 71 is electrically connected to second
lead wiring 72 via diffusion wiring part LAD and coil wiring 5. This can prevent each
of first metal wiring 61 and second metal wiring 62 from being deformed along the
upward curve of a corresponding one of first elastic layer 41 and second elastic layer 42
(see Fig. 5). This in turn can prevent the wiring from being broken. In particular, it
25 is effective in optical scanning device 100 in which first elastic layer 41 and second
elastic layer 42 have large dimensions in the thickness direction.
[0145] Fourth embodiment
With reference to Figs. 20 and 21, a description will be given below of a
configuration of an optical scanning device 100 according to a fourth embodiment.
34
The fourth embodiment is the same in configuration, manufacturing method, and
actions and effects as the first embodiment unless otherwise specified. Therefore, the
same components as the components according to the first embodiment are denoted by
the same reference numerals to avoid the description from being redundant.
5 [0146] In the present embodiment, as illustrated in Fig. 20, optical scanning device 100
further includes a first comb-shaped electrode E1. Rotator 1 includes a second combshaped electrode E2. Optical scanning device 100 does not include magnet M (see
Fig. 1). Optical scanning device 100 according to the present embodiment is different
from optical scanning device 100 according to the first embodiment mainly in that
10 magnet M (see Fig. 1) is not included.
[0147] As illustrated in Fig. 20, optical scanning device 100 includes a third support
part 33. Third support part 33 connects first support part 31 and second support part
32. First comb-shaped electrode E1 is attached to third support part 33. First combshaped electrode E1 extends from third support part 33 toward rotator 1 in the Y-axis
15 direction. Rotator 1 according to the present embodiment may include recess 11 (see
Fig. 4).
[0148] As illustrated in Fig. 21, second comb-shaped electrode E2 is to mesh with first
comb-shaped electrodes E1 in an alternate manner. Second comb-shaped electrode E2
extends toward third support part 33 in the Y-axis direction. First comb-shaped
20 electrode E1 and second comb-shaped electrode E2 are to generate electrostatic force
between first comb-shaped electrode E1 and second comb-shaped electrode E2 when a
voltage is applied to first comb-shaped electrode E1 and second comb-shaped electrode
E2. The electrostatic force acts on first comb-shaped electrode E1 and second combshaped electrode E2 to cause first comb-shaped electrode E1 and second comb-shaped
25 electrode E2 to attract each other. The electrostatic force generates torque about first
torsion beam 21 and second torsion beam 22 in rotator 1. Rotator 1 is to be rotated by
the electrostatic force. This causes rotator 1 to rotate about first torsion beam 21 and
second torsion beam 22.
[0149] Next, actions and effects of the present embodiment will be described.
35
In optical scanning device 100 according to a fifth embodiment, as illustrated in
Fig. 20, optical scanning device 100 further includes first comb-shaped electrode E1
and second comb-shaped electrode E2. Rotator 1 is to be rotated by the electrostatic
force. This eliminates the need for optical scanning device 100 to include magnet M
5 (see Fig. 1). If rotator 1 of optical scanning device 100 is to be rotated by
electromagnetic force, magnet M causes an increase in dimensions of optical scanning
device 100 (see Fig. 1). According to the present embodiment, since optical scanning
device 100 need not include magnet M (see Fig. 1), the dimension of optical scanning
device 100 in the Y-axis direction can be reduced.
10 [0150] Fifth embodiment
With reference to Figs. 22 and 23, a description will be given below of a
configuration of an optical scanning device 100 according to a fifth embodiment. The
fifth embodiment is the same in configuration, manufacturing method, and actions and
effects as the first embodiment unless otherwise specified. Therefore, the same
15 components as the components according to the first embodiment are denoted by the
same reference numerals to avoid the description from being redundant.
[0151] In the present embodiment, as illustrated in Fig. 22, optical scanning device 100
further includes a first piezoelectric actuator 81 and a second piezoelectric actuator 82.
Optical scanning device 100 includes third support part 33. Optical scanning device
20 100 does not include magnet M (see Fig. 1). Optical scanning device 100 according
to the present embodiment is different from optical scanning device 100 according to
the first embodiment mainly in that magnet M (see Fig. 1) is not included.
[0152] As illustrated in Fig. 23, first piezoelectric actuator 81 is connected to first
torsion beam 21. Second piezoelectric actuator 82 is connected to second torsion
25 beam 22. Rotator 1 is to be rotated by first piezoelectric actuator 81 and second
piezoelectric actuator 82. Rotator 1 according to the present embodiment may include
recess 11 (see Fig. 4).
[0153] First piezoelectric actuator 81 includes a first piezoelectric element 80a and a
second piezoelectric element 80b facing each other across first torsion beam 21.
36
Second piezoelectric actuator 82 includes first piezoelectric element 80a and second
piezoelectric element 80b facing each other across second torsion beam 22. First
piezoelectric element 80a and second piezoelectric element 80b are to generate pressure
when a voltage is applied.
5 [0154] First piezoelectric element 80a is to be driven in antiphase to second
piezoelectric element 80b. This causes first piezoelectric element 80a to vibrate in
antiphase to second piezoelectric element 80b. The vibrations of first piezoelectric
element 80a and the second piezoelectric element 80b cause first torsion beam 21 and
second torsion beam 22 to rotate. This causes rotator 1 connected to first torsion
10 beam 21 and second torsion beam 22 to rotate by first piezoelectric actuator 81 and
second piezoelectric actuator 82.
[0155] Next, actions and effects of the present embodiment will be described.
In optical scanning device 100 according to the fifth embodiment, as illustrated
in Fig. 22, in rotator 1, optical scanning device 100 further includes first piezoelectric
15 actuator 81 and second piezoelectric actuator 82. Rotator 1 is to be rotated by first
piezoelectric actuator 81 and second piezoelectric actuator 82. This eliminates the
need for optical scanning device 100 to include magnet M (see Fig. 1). If rotator 1 of
optical scanning device 100 is to be rotated by electromagnetic force, magnet M causes
an increase in dimensions of optical scanning device 100 (see Fig. 1). According to
20 the present embodiment, since optical scanning device 100 need not include magnet M
(see Fig. 1), the dimension of optical scanning device 100 in the Y-axis direction can be
reduced.
[0156] Sixth embodiment
With reference to Figs. 24 and 25, a description will be given below of a
25 configuration of an optical scanning device 100 according to a sixth embodiment.
The sixth embodiment is the same in configuration, manufacturing method, and actions
and effects as the first embodiment unless otherwise specified. Therefore, the same
components as the components according to the first embodiment are denoted by the
same reference numerals to avoid the description from being redundant.
37
[0157] As illustrated in Fig. 23, optical scanning device 100 according to the present
embodiment is applied to a distance measuring device 200. Distance measuring
device 200 is distance measuring device 200 for generating a distance image of a
measurement target 300. Note that, in the present embodiment, the distance image of
5 measurement target 300 is an image showing a distance between distance measuring
device 200 and measurement target 300. As illustrated in Fig. 23, distance measuring
device 200 includes optical scanning device 100, a light source 91, a photodetector 92,
and an operation unit 93. Optical scanning device 100 is optical scanning device 100
according to any one of the first to fifth embodiments. Distance measuring device 200
10 may include a window 94, a beam splitter 95, and a housing 96.
[0158] Light source 91 is to emit light toward reflector 10 of optical scanning device
100. Light source 91 is, for example, a laser light source or the like. In Figs. 24 and
25, distance measuring device 200 includes one light source 91, but distance measuring
device 200 may include a plurality of light sources 91. Light is, for example, laser
15 light having a wavelength of 870 nm to 1500 nm, both inclusive.
[0159] Beam splitter 95 is disposed between light source 91 and optical scanning
device 100. Beam splitter 95 is to allow the light emitted from light source 91 to pass
through to optical scanning device 100. Beam splitter 95 is to reflect light reflected
off reflector 10 of optical scanning device 100.
20 [0160] Optical scanning device 100 is to cause reflector 10 to reflect the light emitted
from light source 91 to measurement target 300. Optical scanning device 100 is to
deflect and reflect incident light. Optical scanning device 100 may be to reflect the
light reflected off measurement target 300 to photodetector 92.
[0161] Photodetector 92 is to receive light. Specifically, photodetector 92 is to detect
25 the light reflected off measurement target 300.
[0162] Operation unit 93 is connected to optical scanning device 100 and light source
91. Operation unit 93 includes, for example, a central processing unit (CPU) or a
processor. Operation unit 93 includes, for example, a circuit having an operation
function. Operation unit 93 is to generate the distance image by comparing the light
38
emitted from light source 91 with the light reflected off measurement target 300.
[0163] Inside housing 96, optical scanning device 100, light source 91, photodetector
92, and operation unit 93 are disposed. Window 94 is provided in housing 96.
[0164] Next, a description will be given of an optical path when distance measuring
5 device 200 generates the distance image of measurement target 300.
[0165] Light is emitted from light source 91. The light emitted from light source 91
impinges on beam splitter 95. The light that has impinged on beam splitter 95 is split.
A part of the light split by beam splitter 95 impinges on reflector 10 of optical scanning
device 100. The light that has impinged on reflector 10 is reflected off reflector 10 to
10 measurement target 300. The light reflected off reflector 10 is applied to
measurement target 300 through window 94. The light applied to measurement target
300 is reflected off measurement target 300. The light reflected off measurement
target 300 impinges on reflector 10 through window 94. The light that has impinged
on reflector 10 is reflected off reflector 10. The light reflected off reflector 10
15 impinges on beam splitter 95. The light that has impinged on beam splitter 95 is split.
A part of the light that has impinged on beam splitter 95 is reflected off a reflector of
beam splitter 95. The light reflected off the reflector of beam splitter 95 impinges on
photodetector 92.
[0166] Operation unit 93 generates the distance image by comparing the light
20 (outgoing light) emitted from light source 91 with the light (incident light) reflected off
measurement target 300. For example, when the outgoing light is emitted in pulses,
the incident light also impinges on photodetector 92 in pulses. For example, operation
unit 93 computes a distance between distance measuring device 200 and measurement
target 300 on the basis of a time difference between the pulse of the outgoing light and
25 the pulse of the incident light.
[0167] Since optical scanning device 100 can scan light two-dimensionally, it is
possible to obtain a distance image of surroundings of distance measuring device 200
on the basis of information on the scanned light.
[0168] With reference to Fig. 25, a description will be given below of a configuration
39
of optical scanning device 100 according to a modification of the sixth embodiment.
[0169] Optical scanning device 100 according to the modification of the sixth
embodiment further includes another optical system 301. The light reflected off
measurement target 300 impinges on distance measuring device 200 via another optical
5 system 301.
[0170] Next, actions and effects of the present embodiment will be described.
Distance measuring device 200 according to the sixth embodiment includes
operation unit 93. Operation unit 93 is to generate the distance image by comparing
the light emitted from light source 91 with the light reflected off measurement target
10 300. This allows a distance image showing distances from measurement target 300 to
be obtained.
[0171] Distance measuring device 200 includes optical scanning device 100 according
to the present disclosure. This allows distance measuring device 200 to reduce the
hard spring effect. Distance measuring device 200 can curb a decrease in the
15 maximum deflection angle of rotator 1. Distance measuring device 200 has high
long-term reliability.
[0172] It should be understood that the embodiments disclosed herein are illustrative in
all respects and not restrictive. The scope of the present disclosure is defined by the
claims rather than the above description, and the present disclosure is intended to
20 include the claims, equivalents of the claims, and all modifications within the scope.
REFERENCE SIGNS LIST
[0173]1: rotator, 5: coil wiring, 10: reflecting surface, 11: recess, 21: first torsion beam,
22: second torsion beam, 31: first support part, 32: second support part, 41: first elastic
layer, 41D: first diffusion wiring part, 42: second elastic layer, 42D: second diffusion
25 wiring part, 71: first lead wiring, 72: second lead wiring, 81: first piezoelectric actuator,
82: second piezoelectric actuator, 91: light source, 92: photodetector, 93: operation unit,
100: optical scanning device, 200: distance measuring device, E1: first comb-shaped
electrode, E2: second comb-shaped electrode, LA: active layer, LAD: diffusion wiring
part, LS: support layer, M: magnet, SUB: substrate

WE CLAIM:
1. An optical scanning device comprising:
a reflector to reflect light;
5 a rotator on which the reflector is superposed;
a first torsion beam and a second torsion beam between which the rotator is
interposed;
a first support part, the first torsion beam being interposed between the first
support part and the rotator;
10 a second support part, the second torsion beam being interposed between the
second support part and the rotator;
a first elastic layer superposed on the first torsion beam; and
a second elastic layer superposed on the second torsion beam,
wherein
15 the rotator is rotatable with respect to the first support part and the second
support part with the first torsion beam and the second torsion beam as a rotation axis,
the rotator, the first torsion beam, and the second torsion beam include a
common active layer,
a vertical dimension of the active layer is smaller than a horizontal dimension of
20 the active layer in a cross section orthogonal to a direction in which the rotator is
interposed between the first torsion beam and the second torsion beam, and
a material of the first elastic layer and the second elastic layer is an elastic
material higher in fatigue life than metal.
25 2. The optical scanning device according to claim 1, wherein
the rotator includes a recess, and
the recess is open on an opposite side to the reflector with respect to the active
layer.
41
3. The optical scanning device according to claim 1 or 2, further comprising a
magnet disposed apart from the rotator,
wherein
the rotator includes a coil wiring superposed on the active layer, and
5 the rotator is to be rotated by a Lorentz force generated by a current flowing
through the coil wiring and a magnetic force generated from the magnet.
4. The optical scanning device according to claim 3, further comprising:
a first lead wiring disposed on the first support part; and
10 a second lead wiring disposed on the second support part,
wherein
the first elastic layer includes a first diffusion wiring part doped with an
impurity,
the second elastic layer includes a second diffusion wiring part doped with an
15 impurity, and
the first lead wiring is electrically connected to the second lead wiring via the
first diffusion wiring part, the coil wiring, and the second diffusion wiring part.
5. The optical scanning device according to claim 3, further comprising:
20 a first lead wiring disposed on the first support part; and
a second lead wiring disposed on the second support part,
wherein
a material of the active layer contains silicon,
the active layer includes a diffusion wiring part doped with an impurity, and
25 the first lead wiring is electrically connected to the second lead wiring via the
diffusion wiring part and the coil wiring.
6. The optical scanning device according to claim 1 or 2, further comprising a
first comb-shaped electrode,
42
wherein
the rotator includes a second comb-shaped electrode to mesh with the first
comb-shaped electrode in an alternate manner,
the first comb-shaped electrode and the second comb-shaped electrode are to
5 generate an electrostatic force between the first comb-shaped electrode and the second
comb-shaped electrode when a voltage is applied to the first comb-shaped electrode
and the second comb-shaped electrode, and
the rotator is to be rotated by the electrostatic force.
10 7. The optical scanning device according to claim 1 or 2, further comprising:
a first piezoelectric actuator connected to the first torsion beam; and
a second piezoelectric actuator connected to the second torsion beam,
wherein the rotator is to be rotated by the first piezoelectric actuator and the
second piezoelectric actuator.
15
8. The optical scanning device according to any one of claims 1 to 7, wherein
the material of the first elastic layer and the second elastic layer contains silicon.
9. The optical scanning device according to claim 8, wherein
20 the material of the first elastic layer and the second elastic layer contains
polysilicon.
10. The optical scanning device according to claim 8, wherein
the material of the first elastic layer and the second elastic layer contains
25 monocrystalline silicon.
11. A distance measuring device for generating a distance image of a
measurement target, the distance measuring device comprising:
the optical scanning device according to any one of claims 1 to 10;

a light source to emit the light toward the reflector of the optical scanning
device;
a photodetector to receive the light; and
an operation unit connected to the optical scanning device and the light source,
5 wherein
the optical scanning device is to cause the reflector to reflect the light emitted
from the light source to the measurement target,
the photodetector is to detect the light reflected off the measurement target, and
the operation unit is to generate the distance image by comparing the light
10 emitted from the light source with the light reflected off the measurement target.
12. A method for manufacturing an optical scanning device, comprising:
preparing a substrate on which an active layer and a support layer are laminated;
providing a first elastic layer and a second elastic layer on an opposite side to
15 the support layer with respect to the active layer, the first elastic layer and the second
elastic layer being made of an elastic material higher in fatigue life than metal, the first
elastic layer and the second elastic layer being provided apart from each other;
laminating, on the active layer between the first elastic layer and the second
elastic layer, a reflector to reflect light; and
20 forming: a first torsion beam by removing the support layer on an opposite side
to the first elastic layer with respect to the active layer; a second torsion beam by
removing the support layer on an opposite side to the second elastic layer with respect
to the active layer; a rotator that is interposed between the first torsion beam and the
second torsion beam and on which the reflector is superposed; a first support part, the
25 first torsion beam being interposed between the first support part and the rotator; and a
second support part, the second torsion beam being interposed between the second
support part and the rotator,
wherein
a vertical dimension of the active layer is smaller than a horizontal dimension of
44
the active layer in a cross section orthogonal to a direction in which the rotator is
interposed between the first torsion beam and the second torsion beam.