Actuator device

Abstract

An actuator device includes a support portion, a movable portion, a first connecting portion that connects the movable portion to the support portion on a first axis in a manner that the movable portion can swing around the first axis, and a first wiring provided on the first connecting portion. The first wiring has a first body portion composed of a metal material having a Vickers hardness of 50 HV or more. The first body portion includes a first surface facing the first connecting portion and a second surface other than the first surface. The second surface has a curved portion that is curved in a manner of protruding toward the first connecting portion side in a cross section perpendicular to an extension direction of the first wiring.

Description

[0001] This application was filed on [date]. June 18, 2018 Application number is 201880042541.7 The invention is named actuator Device A divisional application of the patent application. Technical Field

[0002] One aspect of the present invention relates to an actuator device configured as, for example, a MEMS (Micro Electro Mechanical Systems) device. Background Technology

[0003] As a MEMS device, an actuator device is known, which includes a support portion; a movable portion; a connecting portion on an axis connecting the movable portion and the support portion in such a way that the movable portion can rock around a predetermined axis; and wiring provided on the connecting portion. In such an actuator device, there may be cases where, for example, the movable portion rocks at a high speed at its resonant frequency level (several kHz to tens of kHz). Therefore, if metals such as aluminum or copper are used as the wiring material, there are concerns about degradation of characteristics and wire breakage due to hysteresis behavior, work hardening, etc., resulting in reduced controllability and changes in characteristics over time.

[0004] To address the problems described above, a technique is proposed that forms a diffusion layer by diffusing impurities into a junction made of semiconductor material, and that the junction itself functions as wiring (see, for example, Patent Document 1).

[0005] Existing technical documents

[0006] Patent documents

[0007] Patent Document 1: Japanese Patent Application Publication No. 8-186975 Summary of the Invention

[0008] The problem that the invention aims to solve

[0009] However, since the resistance of the diffusion layer is typically much higher than that of the metallic material, the aforementioned techniques are unsuitable for handling large currents, such as when the movable part is rocked at high speed and large angle. Therefore, in order to reduce resistance and suppress metal fatigue, wiring made of a high-hardness metallic material is considered. However, there is a concern that the wiring may experience brittle fracture due to stress concentration when the movable part is rocked.

[0010] One aspect of the present invention is to provide an actuator device that can reduce the resistance of wiring provided on the connection portion, suppress metal fatigue, and improve reliability.

[0011] Technical means to solve the problem

[0012] An actuator device according to one aspect of the present invention includes: a support portion; a movable portion; a first connecting portion that connects the movable portion to the support portion on a first axis in such a way that the movable portion can rock around a first axis; and a first wiring disposed on the first connecting portion. The first wiring has a first main body portion made of a metallic material with a Vickers hardness of 50 HV or higher. The first main body portion includes a first surface facing the first connecting portion and a second surface other than the first surface. The second surface has a shape in which the curvature is continuous throughout the second surface in a cross section perpendicular to the extension direction of the first wiring.

[0013] In this actuator device, the first wiring disposed at the first connection portion has a first main body portion made of a metallic material with a Vickers hardness of 50 HV or higher. Therefore, compared to the case where the entire first wiring is composed of a diffusion layer, lower resistance can be achieved in the first wiring, and compared to the case where the entire first wiring is composed of a metallic material with a Vickers hardness less than 50 HV, metal fatigue can be suppressed. Furthermore, the second surface of the first main body portion has a shape in which the curvature is continuous throughout the entire second surface in a cross-section perpendicular to the extension direction of the first wiring. Therefore, since there are no points of curvature discontinuity on the second surface, stress concentration is suppressed. As a result, brittle fracture in the first wiring can be suppressed. In particular, if points of curvature discontinuity exist on the second surface, notches, scratches, etc., are easily generated on the second surface during the manufacturing process of the actuator device, etc., and there is a concern that stress concentration may occur at the locations where these defects occur. In this actuator device, since the second surface has a shape of continuous curvature throughout the entire second surface, the generation of such stress concentration can be suppressed. Therefore, according to this actuator device, it is possible to reduce the resistance of the wiring provided on the connection and suppress metal fatigue, and improve reliability.

[0014] In an actuator device according to one aspect of the invention, the second surface may also have a curved portion in a cross-section perpendicular to the extension direction of the first wiring, bending in a manner that protrudes toward the opposite side of the first connection. In this case, brittle fracture in the first wiring can be suppressed, and the cross-sectional area of ​​the first wiring can be ensured, thereby achieving further reduction in the resistance of the first wiring.

[0015] In one aspect of the actuator device according to the invention, the second surface may also intersect the first surface at an acute angle in a cross-section perpendicular to the extension direction of the first wiring. In this case, stress concentration at the intersection of the second and first surfaces can be suppressed, further improving reliability.

[0016] In one aspect of the actuator device according to the present invention, the first connection portion may be made of a semiconductor material, and a diffusion layer containing diffused impurities may be formed in the first connection portion in such a way as to contact the first wiring. In this case, since the diffusion layer functions as part of the first wiring, further reduction of the resistance of the first wiring can be achieved.

[0017] In one aspect of the actuator device according to the present invention, the first main body may also be composed of at least one of tungsten, titanium, nickel, molybdenum, aluminum alloy, tungsten alloy, titanium alloy, nickel alloy, and stainless steel. In this case, the aforementioned effects can be appropriately obtained, namely, the wiring provided on the connection portion can be made less resistant, metal fatigue can be suppressed, and reliability can be improved.

[0018] In one aspect of the actuator device according to the invention, the first wiring may also have a seed layer disposed between the first connecting portion and the first main body portion. In this case, the tightness of the first main body portion relative to the first connecting portion can be improved.

[0019] In one aspect of the actuator device according to the present invention, the seed layer may also be made of a metallic material with a Vickers hardness of 50 HV or higher. In this case, metal fatigue and brittle fracture occurring in the seed layer can be suppressed.

[0020] In one aspect of the actuator device according to the present invention, a barrier layer may further be provided, which is disposed between the first connection and the first wiring. In this case, even if an easily diffusing metallic material is contained in the first wiring, the diffusion of the metallic material to the first connection can be suppressed.

[0021] In one aspect of the actuator device according to the present invention, the barrier layer may also be made of a material with a Vickers hardness of 50 HV or higher. In this case, metal fatigue and brittle fracture can be suppressed in the barrier layer.

[0022] In one aspect of the actuator device according to the present invention, a second wiring may be further included, which is disposed on the support and connected to the first wiring, the second wiring being made of a metal material with a Vickers hardness of less than 50 HV. In this case, by making the second wiring, for example, of a metal material with low resistivity, the resistance of the second wiring disposed on the support can be reduced.

[0023] In one aspect of the actuator device according to the present invention, it may further include: a frame portion supporting a support portion and a movable portion; a second connecting portion connecting the support portion to the frame portion on a second axis such that the support portion can rock around a second axis intersecting the first axis; and a third wiring disposed on the second connecting portion, the third wiring having a second main body portion made of a metal material with a resistivity lower than that of the metal material constituting the first main body portion. In this case, the resistance of the third wiring disposed on the second connecting portion can be reduced.

[0024] In one aspect of the actuator device according to the present invention, it may further include: a frame portion supporting a support portion and a movable portion; a second connecting portion connecting the support portion to the frame portion on a second axis such that the support portion can rock around a second axis intersecting the first axis; and a third wiring disposed on the second connecting portion, the third wiring having a second main body portion made of a metallic material with a Vickers hardness of 50 HV or higher, the second main body portion including: a third surface facing the second connecting portion and a fourth surface other than the third surface, the fourth surface having a shape in which the curvature is continuous throughout the fourth surface in a cross section perpendicular to the extending direction of the third wiring. In this case, even for the third wiring disposed on the second connecting portion, low resistance and suppression of metal fatigue can be achieved, and high reliability can be obtained.

[0025] In one aspect of the actuator device according to the present invention, a mirror disposed on the movable part may be further included. In this case, the mirror can be oscillated around the first axis for scanning light, etc.

[0026] The effects of the invention

[0027] According to one aspect of the present invention, an actuator device can be provided that can reduce the resistance of the wiring provided on the connection portion, suppress metal fatigue, and improve reliability. Attached Figure Description

[0028] Figure 1 This is a perspective view showing the actuator device involved in the embodiment.

[0029] Figure 2 It is shown Figure 1 A top view of the circuit structure of the actuator device shown.

[0030] Figure 3 It is along Figure 2 A partial cross-sectional view of line III-III.

[0031] Figure 4 It is along Figure 3 A partial cross-sectional view of line IV-IV.

[0032] Figure 5 It is along Figure 3 A partial cross-sectional view of the VV line.

[0033] Figure 6 This is a microscope photograph showing a cross-section of the first trial wiring.

[0034] Figure 7 (a)~ Figure 7 (c) is a schematic cross-sectional view of the first to third comparative examples.

[0035] Figure 8 This is a microscope photograph showing a cross-section of the wiring of the third comparative example.

[0036] Figure 9 (a) and Figure 9 (b) is a schematic cross-sectional view of the first and second variations.

[0037] Figure 10 This is a schematic cross-sectional view of the third variation.

[0038] Figure 11 This is a schematic cross-sectional view of the fourth variation. Detailed Implementation

[0039] In the following description, embodiments of one aspect of the invention will be described in detail with reference to the accompanying drawings. Furthermore, in the following description, the same or equivalent elements are referred to by the same reference numerals, and repeated descriptions are omitted.

[0040] like Figure 1 and Figure 2 As shown, the actuator device 1 includes: a mirror 2, a magnetic field generating unit 3, a frame unit 4, a support unit 5, a movable unit 6, a pair of second connecting parts 7, and a pair of first connecting parts 8. The actuator device 1 is configured as a MEMS device that causes the mirror 2 to rock around each of the mutually orthogonal first axis X1 and second axis X2. Such an actuator device 1 is used, for example, as an optical switch for optical communication or an optical scanner.

[0041] Mirror 2 is a light-reflecting film made of metal film. Mirror 2 is circular in shape when viewed from above (when viewed from a direction orthogonal to the plane in which at least the support 5, the movable part 6, and the pair of first connecting parts 8 are arranged). The metal material constituting mirror 2 is, for example, aluminum (Al), aluminum alloy, gold (Au), silver (Ag), silver alloy, etc.

[0042] The magnetic field generating unit 3 is a rectangular plate with a pair of main surfaces. The magnetic field generating unit 3 applies a magnetic field to coil 11, which is mounted on the support unit 5, and coil 12, which is mounted on the movable unit 6 (coils 11 and 12 will be described later). The magnetic field generating unit 3 is, for example, constructed from a permanent magnet. The arrangement of the magnetic poles in the magnetic field generator 3 is, for example, a Halbach arrangement.

[0043] The frame portion 4 is a flat, rectangular frame when viewed from above. The frame portion 4 is disposed on one main surface of the magnetic field generating portion 3. The frame portion 4 supports the support portion 5, the movable portion 6, and the mirror 2 via a pair of second connecting portions 7. Each second connecting portion 7 connects the support portion 5 to the frame portion 4 along the second axis X2 in such a way that the support portion 5 can rock around the second axis X2. That is, each second connecting portion 7 functions as a torsion bar. Each second connecting portion 7 has a meandering shape when viewed from above to improve strength and facilitate adjustment of the torsion spring constant. More specifically, each second connecting portion 7 has a plurality of straight portions 7a extending in the direction of the second axis X2 and arranged in the direction of the first axis X1, and a plurality of folded portions 7b alternately connecting the two ends of the plurality of straight portions 7a. The plurality of folded portions 7b includes folded portions that extend in a straight line and folded portions that bend and extend in an R-shape.

[0044] The support portion 5 is a flat, plate-shaped frame that is rectangular in shape when viewed from above, located inside the frame portion 4. The support portion 5 is arranged such that it faces and is separated from one main surface of the magnetic field generating portion 3. The support portion 5 supports the movable portion 6 and the mirror 2, etc., via a pair of first connecting portions 8. Each first connecting portion 8 connects the movable portion 6 to the support portion 5 along the first axis X1 such that the movable portion 6 can rock around the first axis X1. That is, each first connecting portion 8 functions as a torsion bar. Each first connecting portion 8 is a flat, plate-shaped member that is generally rectangular in shape when viewed from above, extending linearly along the first axis X1.

[0045] The movable part 6 has a frame F and a mounting part 9, located inside the support part 5. The frame F is a flat plate that is rectangular in shape when viewed from above, and is connected to the first connecting part 8. The mounting part 9 is a flat plate that is circular in shape when viewed from above, positioned inside the frame F, and connected to the frame F. The movable part 6 is arranged such that it faces and is separated from one main surface of the magnetic field generating part 3. The mirror 2 is mounted on the mounting part 9. That is, the mirror 2 is provided on the movable part 6. The frame part 4, the support part 5, the movable part 6, a pair of second connecting parts 7, and a pair of first connecting parts 8 are integrally formed of a semiconductor material such as silicon (Si). Furthermore, in Figure 2 In the example shown, a gap is formed between the frame F and the configuration part 9, but the frame F and the configuration part 9 can also be arranged continuously without forming a gap between them.

[0046] like Figure 2 As shown, the actuator device 1 also includes a coil 11 disposed in the support portion 5 and a coil 12 disposed in the movable portion 6. The coil 11 is embedded in the support portion 5, and the coil 12 is embedded in the movable portion 6. Each coil 11 and 12 is made of a metallic material such as copper (Cu). Furthermore, in Figure 2 For ease of understanding, each wiring is represented by a solid line. The wiring of coils 11, 12, etc. is actually covered by the insulation layers 51, 52 and / or 53 described below.

[0047] When viewed from above, coil 11 is spirally wound multiple times. One end of wire 14a is electrically connected to the inner end of coil 11. One end of wire 14b is electrically connected to the outer end of coil 11. Each wire 14a and 14b is made of the second metallic material described below. Each wire 14a and 14b is disposed on a connecting part 7 and extends from the support part 5 to the frame part 4. The other end of wire 14a is electrically connected to the electrode 15a disposed on the support part 5, and the other end of wire 14b is electrically connected to the electrode 15b disposed on the support part 5. Each electrode 15a and 15b is electrically connected to control circuitry, etc. Wire 14a crosses coil 11 three-dimensionally, passing above coil 11.

[0048] When viewed from above, coil 12 is wound in a spiral shape with multiple turns. One end of wire 16a is electrically connected to the inner end of coil 12. One end of wire 16b is electrically connected to the outer end of coil 12. Each wire 16a and 16b is disposed on a pair of first connecting parts 8, support parts 5, and another second connecting part 7, and extends from movable part 6 to frame part 4. The other end of wire 16a is electrically connected to electrode 17a disposed on support part 5, and the other end of wire 16b is electrically connected to electrode 17b disposed on support part 5. Each electrode 17a and 17b is electrically connected to control circuitry, etc. Wire 16a crosses coil 12 three-dimensionally, passing above coil 12.

[0049] Each wiring 16a, 16b has a first wiring 21 disposed on each first connecting part 8, and second wirings 31A, 31B disposed on the support part 5 and the movable part 6 respectively.

[0050] The first wiring 21 is made of a first metallic material. The first wiring 21 is provided across the support portion 5, the first connecting portion 8, and the movable portion 6. The first wiring 21 has a first portion 22, a second portion 23, and a third portion 24. The first portion 22 extends along a first axis X1 on the support portion 5, the first connecting portion 8, and the movable portion 6. The second portion 23 extends on the support portion 5 from the end of the first portion 22 on the support portion 5 side to the side of another second connecting portion 7. The third portion 24 extends on the movable portion 6 from the end of the first portion 22 on the movable portion 6 side to the side of another second connecting portion 7. The extending directions of the first portion 22 and the second portion 23 are orthogonal to each other, and the extending directions of the first portion 22 and the third portion 24 are orthogonal to each other. The end of the first wiring 21 on the support portion 5 is electrically connected to the second wiring 31A. The end of the first wiring 21 on the movable portion 6 is electrically connected to the second wiring 31B.

[0051] Second wirings 31A and 31B are made of a second metallic material. One end of second wiring 31A is electrically connected to first wiring 21. The other end of second wiring 31A is electrically connected to electrode 17a. At one end of second wiring 31A, a width extension portion 32A is provided, which is wider than other portions. Second wiring 31A is electrically connected to first wiring 21 at the width extension portion 32A. One end of second wiring 31B is electrically connected to first wiring 21. The other end of second wiring 31B is electrically connected to coil 12. At one end of second wiring 31B, a width extension portion 32B is provided, which is wider than other portions. Second wiring 31B is electrically connected to first wiring 21 at the width extension portion 32B.

[0052] The Vickers hardness of the first metallic material constituting the first wiring 21 is 50 HV or higher. The Vickers hardness is measured by the test method specified in JIS Z 2244:2009. The first metallic material is, for example, at least one selected from tungsten (W), titanium (Ti), nickel, molybdenum (Mo), aluminum alloys, tungsten alloys, titanium alloys, nickel alloys, and stainless steel. Examples of aluminum alloys include duralumin. Stainless steel is an alloy containing 50% or more iron (Fe) and 10.5% or more chromium (Cr). The Vickers hardness of the alloy varies depending on its constituent materials. When the first metallic material is an alloy, an alloy with a Vickers hardness of 50 HV or higher is used as the first metallic material. When the first metallic material is nickel, titanium, tungsten, or duralumin, the Vickers hardness of the first metallic material is 96 HV, 120 HV, 100 HV to 350 HV, and 115 HV to 128 HV, respectively. The Vickers hardness of the first metallic material may also be 500 HV or lower.

[0053] The Vickers hardness of the second metallic material constituting the second wirings 31A and 31B is less than 50 HV. That is, the Vickers hardness of the second metallic material is less than that of the first metallic material. In other words, the Vickers hardness of the first metallic material is greater than that of the second metallic material. The second metallic material is, for example, aluminum, copper, aluminum-copper alloys, aluminum-silicon-copper alloys, aluminum-silicon-titanium alloys, aluminum-silicon alloys, or aluminum-titanium alloys. When the second metallic material is an alloy, an alloy with a Vickers hardness less than 50 HV is used as the second metallic material. When the second metallic material is aluminum or copper, the Vickers hardness of the second metallic material is 25 HV and 46 HV, respectively. The metallic materials constituting the second wiring 31A and the metallic materials constituting the second wiring 31B can also be different from each other. The resistivity of the second metallic material can also be less than that of the first metallic material. In other words, the resistivity of the first metallic material can also be greater than that of the second metallic material. Furthermore, in metallic materials, there is a tendency for the resistivity to decrease as the Vickers hardness decreases.

[0054] In this embodiment, the resistivity of the metal material constituting the wiring provided on each of the second connection portions 7 (hereinafter referred to as the third wiring) is less than the resistivity of the first metal material. The third wiring is the portion of wirings 14a and 14b located on the second connection portion 7, and the portion of second wirings 31A and 31B located on the second connection portion 7. As a combination of metal materials satisfying the above-described resistivity relationship, for example, the metal material constituting the third wiring is aluminum, copper, aluminum-copper alloy, aluminum-silicon-copper alloy, aluminum-silicon-titanium alloy, aluminum-silicon alloy, or aluminum-titanium alloy. The first metal material can be listed as a combination of at least one of tungsten, titanium, nickel, molybdenum, aluminum alloy, tungsten alloy, titanium alloy, nickel alloy, and stainless steel. Furthermore, in this embodiment, the third wiring is configured as part of the second wirings 31A and 31B, but the third wiring may also be configured separately from the second wirings 31A and 31B and electrically connected to them. In this case, the metal material constituting the third wiring and the metal material constituting the second wirings 31A and 31B may also be different from each other. In this embodiment, the third wiring is configured as part of wirings 14a and 14b. However, the third wiring may also be configured separately from wirings 14a and 14b, and electrically connected to them. In this case, the metal material constituting the third wiring may be different from the metal material constituting wirings 14a and 14b.

[0055] like Figures 3-5As shown, the actuator device 1 also includes insulating layers 51, 52, and 53. Each insulating layer 51, 52, and 53 is made of, for example, silicon dioxide (SiO2) or silicon nitride (SiN). Insulating layer 51 is disposed on the surface of the frame portion 4, the support portion 5, the movable portion 6, a pair of second connecting portions 7, and a pair of first connecting portions 8. Insulating layers 52 and 53 are disposed on the insulating layer 51 on the movable portion 6.

[0056] like Figure 3 As shown, a first portion 22 of the first wiring 21 is disposed on a flat surface 8a of the first connection portion 8. That is, the first portion 22 (first wiring 21) is mounted on the surface 8a of the first connection portion 8. The first wiring 21 has a seed layer 25 disposed on the surface 8a and a first main body portion 26 disposed on the seed layer 25. That is, the seed layer 25 is disposed between the first connection portion 8 and the first main body portion 26. In this example, both the seed layer 25 and the first main body portion 26 are made of the first metal material described above. For example, the seed layer 25 is made of titanium, and the first main body portion 26 is made of tungsten. The first main body portion 26 is the portion of the first wiring 21 that mainly carries current and has the largest cross-sectional area. Viewed from the direction along the surface 8a of the first connection portion 8, the first main body portion 26 is located on a side further away from the first connection portion 8 than other portions of the first wiring 21. The seed layer 25 has the function of improving the adhesion of the first main body portion 26 to the first connection portion 8, which is made of silicon. The first main body 26 may also be made of nickel, molybdenum, aluminum alloy, tungsten alloy, titanium alloy, nickel alloy, or stainless steel. The seed layer 25 may also be omitted, and the first main body 26 may be directly disposed on the surface 8a. In this case, the first main body 26 may also be made of tungsten, titanium, nickel, molybdenum, aluminum alloy, tungsten alloy, titanium alloy, nickel alloy, or stainless steel.

[0057] The first main body portion 26 in the first part 22 has a first surface 27 facing the first connecting portion 8 and a second surface 28 other than the first surface 27. The first surface 27 faces the first connecting portion 8 via the seed layer 25 and is formed flatly throughout the first surface 27. The second surface 28 has a cross-section perpendicular to the extending direction of the first part 22 (parallel to the first axis X1). Figure 3The cross-section shown has a shape where the curvature is continuous throughout the second surface 28. In other words, in this cross-section, there are no points of curvature discontinuity on the second surface 28. A point of curvature discontinuity refers to, for example, the vertex of a sharp corner (including any of acute, right, or obtuse angles). The second surface 28 in this cross-section has a flat portion 28a extending parallel to surface 8a, and a pair of curved portions 28b that are continuous at both ends of the flat portion 28a and curve toward the opposite side of the first connecting portion 8. Here, the curvature of the flat portion 28a (the straight portion) can be considered to be 0, and the curvature is also continuous at the boundary between the flat portion 28a and the curved portions 28b. The second surface 28 in this cross-section does not have a portion that curves toward the first connecting portion 8, and as a whole, it is convex toward the opposite side of the first connecting portion 8. The second surface 28 intersects the first surface 27 at the curved portions 28b. The second surface 28 intersects the first surface 27 at an acute angle (less than 90 degrees) in this cross-section. The angle θ formed by the second surface 28 and the first surface 27 is, for example, about 45 degrees or less. Here, angle θ is the angle of the inner side of the angle formed by the second surface 28 and the first surface 27. As in this embodiment, when the second surface 28 is curved at the intersection with the first surface 27, angle θ is the angle formed by the tangent of the second surface 28 at that intersection with the first surface 27.

[0058] The seed layer 25 in the first part 22 has a surface 25a connected to the second surface 28. Surface 25a extends substantially perpendicularly to the surface 8a of the first connecting portion 8, for example. The angle formed by surface 25a and surface 8a (the angle of the inner side formed by surface 25a and surface 8a) can also be about 45 degrees to about 90 degrees. When the angle formed by surface 25a and surface 8a is relatively large, as described above, it is easier to smoothly form the end of surface 25a on the side of the first connecting portion 8 by etching compared to the case where the angle is small. As a result, stress concentration in the seed layer 25 can be suppressed.

[0059] An insulating layer 51 is provided such that it rests on the first wiring 21. A diffusion layer 8b is formed on the surface 8a of the first connection portion 8, in contact with the first wiring 21, covering the entire area opposite to the first wiring 21. The diffusion layer 8b is formed over the support portion 5, the movable portion 6, and the first connection portion 8. The diffusion layer 8b is, for example, a diffusion region formed by diffusing p-type impurities on the surface of an n-type silicon substrate, or a diffusion region formed by diffusing n-type impurities on the surface of a p-type silicon substrate.

[0060] The second portion 23 and the third portion 24 of the first wiring 21 also have the same layer structure and cross-sectional shape as the first portion 22. That is, even the upper surface of the first main body portion 26 in the second portion 23 (the surface other than the surface facing the support portion 5) has a shape with continuous curvature across the entire upper surface in a cross-section perpendicular to the extending direction of the second portion 23 (parallel to the second axis X2). Similarly, the upper surface of the first main body portion 26 in the third portion 24 (the surface other than the surface facing the movable portion 6) also has a shape with continuous curvature across the entire upper surface in a cross-section perpendicular to the extending direction of the third portion 24 (parallel to the second axis X2). Thus, "cross-section perpendicular to the extending direction of the first wiring 21" refers to the cross-section perpendicular to the extending direction of each portion when the first wiring 21 has multiple portions extending in mutually different directions. In this example, the first wiring 21 has a cross-sectional shape that is the same along the extending direction.

[0061] Figure 6 This is a microscope image showing a cross-section of the prototype first wiring. This first wiring 21 with such a cross-sectional shape can be formed by photolithography, dry etching, or wet etching. For example, when using photolithography, a three-dimensional circular resist pattern can be formed by using a grayscale mask or baking a photoresist. By transferring this resist pattern onto a silicon substrate, the desired wiring shape can be obtained.

[0062] like Figure 4 As shown, the second wiring 31A is disposed inside the insulating layer 51. That is, the second wiring 31A is disposed on the support portion 5 and the second connecting portion 7 via the insulating layer 51. The second wiring 31A is formed, for example, in a rectangular cross-sectional shape.

[0063] like Figure 5 As shown, the movable part 6 has a slot 55 with a shape corresponding to the coil 12. An insulating layer 51 is provided on the inner surface of the slot 55. A seed layer 56 is provided on the insulating layer 51 inside the slot 55. The seed layer 56 is made of, for example, titanium nitride. The coil 12 is disposed in the slot 55 via the insulating layer 51 and the seed layer 56. The coil 12 is formed by embedding a metal material such as copper into the slot 55 by, for example, an inlay method. The insulating layer 52 is provided to cover the coil 12 disposed in the slot 55. The second wiring 31B has the same cross-sectional shape as, for example, the second wiring 31A, and is provided on the insulating layer 52. That is, the second wiring 31B is provided on the movable part 6 via the insulating layers 51 and 52. The second wiring 31B is electrically connected to the coil 12 by being provided in the opening of the insulating layer 52 so that the inner end of the coil 12 is exposed. An insulating layer 53 is provided on the second wiring 31B.

[0064] During the formation of coil 12, a groove 13 is formed along the surface of the insulating layer 52 and the boundary of the seed layer 56 in coil 12. The insulating layer 52 has a groove 52a on the surface opposite to the movable part 6, corresponding to the groove 13. The groove 52a is formed during the formation of the insulating layer 52 such that a portion of the insulating layer 52 enters the groove 13. The insulating layer 53 has a groove 53a on the surface opposite to the movable part 6, corresponding to the groove 52a. The groove 53a is formed during the formation of the insulating layer 53 such that a portion of the insulating layer 53 enters the groove 52a.

[0065] In actuator device 1, when current flows into coil 11, the magnetic field generated in magnetic field generating section 3 produces a Lorentz force on the electrons flowing through coil 11 in a predetermined direction. Thus, coil 11 experiences a force in the predetermined direction. Therefore, by controlling the direction or magnitude of the current flowing into coil 11, support section 5 can be rocked around the second axis X2. Similarly, by controlling the direction or magnitude of the current flowing into coil 12, movable section 6 can be rocked around the first axis X1. Therefore, by controlling the direction or magnitude of the current in coils 11 and 12 respectively, mirror 2 can be rocked around the mutually orthogonal first axis X1 and second axis X2. Furthermore, by flowing current into coil 12 at a frequency corresponding to the resonant frequency of movable section 6, movable section 6 can be rocked horizontally at a high speed at the resonant frequency. In this case, the first connecting section 8, located on the inner side (the side closer to mirror 2), rocks at a higher speed than the second connecting section 7, located on the outer side.

[0066] In the actuator device 1 described above, the first wiring 21 provided on the first connecting portion 8 has a first main body portion 26 made of a first metallic material with a Vickers hardness of 50 HV or higher. Therefore, compared to the case where the entire first wiring 21 is made of a diffusion layer, the resistance of the first wiring 21 can be reduced, and compared to the case where the entire first wiring 21 is made of a metallic material with a Vickers hardness of less than 50 HV, metal fatigue can be suppressed. Furthermore, the second surface 28 of the first main body portion 26 has a shape in which the curvature is continuous throughout the entire second surface 28 in a cross-section perpendicular to the extending direction of the first wiring 21. Therefore, since there are no points of curvature discontinuity on the second surface 28, stress concentration is suppressed. As a result, brittle fracture of the first wiring 21 can be suppressed.

[0067] Here, for reference Figure 7 (a) Figure 7 (b) Figure 7 (c) and Figure 8 The superiority of having no points of curvature discontinuity on the second surface 28 of the first wiring 21 will be further explained. Figure 7 (a)~ Figure 7 In the first, second, and third comparative examples shown in (c), a wiring 121 corresponding to the first wiring 21 is provided on the connecting portion 10 corresponding to the first connecting portion 8. An insulating layer 151 corresponding to the insulating layer 51 is provided on the connecting portion 108 and the wiring 121. In any of the first to third comparative examples, points P1, P2, and P3 with discontinuous curvature exist on the upper surface 128 of the wiring 121 (the surface other than the surface facing the connecting portion 108). Points P1 to P3 are the vertices of sharp corners. Points P1 to P3 are formed at the connection points between flat portions or at the connection points between flat portions and curved portions. The point of discontinuity of curvature exists at the connection points between curved portions. Figure 8 This is a microscope photograph showing a cross-section of the wiring of the third comparative example. Wiring 121 with such a cross-sectional shape is formed, for example, by the same method as the first wiring 21 of the embodiment.

[0068] In comparative examples 1-3, where there are curvature discontinuities P1-P3 on the upper surface 128 of the wiring 121, there is a concern that notches, scratches, etc., may easily occur on the upper surface 128 during the manufacturing process of the actuator device, and stress concentration may occur at the locations where these defects occur. Specifically, for example, during etching for wiring formation or during processing in the manufacturing process, external forces applied to points P1-P3 may cause notches, scratches, etc., to occur in these areas. In such cases, when the movable part shakes, stress concentration occurs at the locations where notches or scratches occur, raising concerns about brittle fracture. In contrast, in actuator device 1, since the second surface 28 of the first wiring 21 has a shape with continuous curvature throughout, the generation of such stress concentration can be suppressed.

[0069] Therefore, according to the actuator device 1, it is possible to reduce the resistance of the first wiring 21 provided on the first connection portion 8, suppress metal fatigue, and improve reliability. However, assuming that the first wiring 21 is constructed as an embedded wiring within a groove, like the coil 21, the following disadvantages exist. First, copper is generally used as the material for the embedded wiring, but since the Vickers hardness of copper is less than 50 HV, metal fatigue is prone to occur in the wiring. Therefore, there are concerns about nonlinearity of the spring constant due to plastic deformation, hysteresis behavior, reduced controllability due to work hardening, and changes in characteristics over time. Furthermore, in embedded wiring, corners are formed within the groove, and since multiple points of curvature discontinuity exist on the surface within the groove, stress concentration is easily generated.

[0070] In actuator device 1, the second surface 28 has a bent portion 28b in a cross-section perpendicular to the extending direction of the first wiring 21, which bends toward the side opposite to the first connection portion 8. In this case, brittle fracture of the first wiring 21 can be suppressed and the cross-sectional area of ​​the first wiring 21 can be ensured, thereby achieving further low resistance of the first wiring 21. That is, in actuator device 1, the cross-sectional area of ​​the first wiring 21 is larger than, for example, if the bent portion 28b is assumed to be bent toward the side of the first connection portion 8.

[0071] In actuator device 1, the second surface 28 intersects the first surface 27 at an acute angle in a cross section perpendicular to the extension direction of the first surface 27. This suppresses stress concentration at the intersection of the second surface 28 and the first surface 27, further improving reliability.

[0072] In the actuator device 1, a diffusion layer 8b diffused with impurities is formed on the first connection portion 8 in such a way that it contacts the first wiring 21. As a result, since the diffusion layer 8b functions as part of the first wiring 21, further reduction of the resistance of the first wiring 21 can be achieved.

[0073] In the actuator device 1, the first main body 26 is made of at least one of tungsten, titanium, nickel, molybdenum, aluminum alloy, tungsten alloy, titanium alloy, nickel alloy, and stainless steel. This allows for the appropriate attainment of the aforementioned effects, namely, reducing the resistance of the first wiring 21 provided on the first connection portion 8, suppressing metal fatigue, and improving reliability.

[0074] In the actuator device 1, the first wiring 21 also has a seed layer 25 disposed between the first connecting portion 8 and the first main body portion 26. This improves the tightness of the first main body portion 26 relative to the first connecting portion 8.

[0075] In actuator device 1, seed layer 25 is made of a metallic material with a Vickers hardness of 50 HV or higher. This suppresses metal fatigue and brittle fracture from occurring in seed layer 25.

[0076] In the actuator device 1, the second wiring 31A provided on the support portion 5 is made of a second metallic material with a Vickers hardness of less than 50 HV. Therefore, by using, for example, a material with low resistivity as the second metallic material, the resistance of the second wiring 31A provided on the support portion 5 can be reduced.

[0077] In the actuator device 1, the mirror 2 is disposed in the movable part 6. Thus, the mirror 2 can be rocked around the first axis X1 and used for scanning light, etc.

[0078] The present invention has been described above as one embodiment, but the present invention is not limited to the above embodiment. For example, the materials and shapes of each component are not limited to those described above, and various materials and shapes can be used.

[0079] The first wiring 21 can also be as follows: Figure 9 As shown in the first and second variations (a) and 9(b), the structure is as described in the first and second variations. In the first and second variations, the diffusion layer 8b is not formed, and the insulating layer 57 is disposed on the first connection portion 8. The first wiring 21 is disposed on the insulating layer 57. That is, the first wiring 21 is disposed on the first connection portion 8 via the insulating layer 57. The first surface 27 of the first main body portion 26 faces the first connection portion 8 via the seed layer 25 and the insulating layer 57. In either the first or second variation, the second surface 28 of the first main body portion 26 has a shape in which the curvature is continuous throughout the second surface 28 in a cross section perpendicular to the extending direction of the first wiring 21. In the first variation, the angle θ formed by the second surface 28 and the first surface 27 is, for example, about 45 degrees to about 90 degrees. In the second variation, the second surface 28, in addition to the flat portion 28a and the curved portion 28b, further has a curved portion 28c that bends toward the first connection portion 8 in this cross section. In the second variation, the angle θ formed by the second surface 28 and the first connecting portion 8 is, for example, about 45 degrees or less. According to such first and second variations, similar to the above-described embodiment, it is possible to reduce the resistance of the first wiring 21 provided on the first connecting portion 8, suppress metal fatigue, and improve reliability.

[0080] When comparing the above embodiment with the first and second modifications, in the above embodiment, the angle θ formed by the second surface 28 and the first surface 27 is smaller than that in the first modification. Therefore, compared to the first modification, stress concentration at the intersection of the second surface 28 and the first surface 27 can be further suppressed. Furthermore, in the above embodiment, since the curved portion 28b extends to the intersection of the second surface 28 and the first surface 27, assuming the height of the first main body 26 is the same, the area where the curved portion 28b is formed is wider than in the second modification. Therefore, the cross-sectional area of ​​the first wiring 21 can be increased, and lower resistance can be achieved. On the other hand, when comparing the first modification with the second modification, in the first modification, since the angle θ is larger than in the second modification, the cross-sectional area of ​​the first wiring 21 can be increased, and lower resistance can be achieved. In contrast, in the second modification, since the angle θ is smaller than in the first modification, stress concentration at the intersection of the second surface 28 and the first surface 27 can be suppressed compared to the first modification. Furthermore, in the second modified example, the presence of curved portions 28b and 29c allows for stress dispersion.

[0081] like Figure 10 As shown in the third variation, the actuator device 1 may further include a barrier layer 41. In the third variation, the first main body 26 is made of aluminum alloy, tungsten alloy, titanium alloy, nickel alloy, or stainless steel, and the first main body 26 contains a metal material with a high diffusion coefficient (e.g., zinc (Zn) or copper). To suppress the diffusion of this metal material, a barrier layer 41 is provided on the insulating layer 57, and a first wiring 21 is provided on the barrier layer 41. That is, the barrier layer 41 is provided between the first connection portion 8 and the first wiring 21. The barrier layer 41 is made of a metal material or an insulating material with a Vickers hardness of 50 HV or higher. The material constituting the barrier layer 41 is, for example, titanium, titanium nitride, or tungsten. In this example, the barrier layer 41 has a first layer 42 provided on the insulating layer 57 and a second layer 43 provided on the first layer 42. For example, the first layer 42 is made of titanium, and the second layer 43 is made of titanium nitride (TiN) or tungsten. The second layer 43 is the layer that mainly functions as a barrier. Even in this third variation, similar to the embodiments described above, it is possible to achieve low resistance of the first wiring 21 provided on the first connection portion 8, suppression of metal fatigue, and improved reliability. Furthermore, the diffusion of the metallic material contained in the first main body portion 26 into the first connection portion 8 can be suppressed. Moreover, metal fatigue and brittle fracture occurring in the barrier layer 41 can be suppressed. Additionally, the first layer 42 can be omitted, and the second layer 43 can be directly provided on the insulating layer 57.

[0082] It can also be like Figure 11 The seed layer 25 is formed as shown in the fourth variation. In the fourth variation, the cross-section ( ) perpendicular to the extension direction of the first wiring 21 (parallel to the first axis X1) is... Figure 11 In the cross-section shown, the curvature at the boundary between the second surface 28 of the first wiring 21 and the surface 25a of the seed layer 25 is continuous. Surface 25a has a shape in which the curvature is continuous throughout the entire surface 25a. That is, in the first wiring 21, the second surface 28 of the first main body portion 26 and the surface 25a of the seed layer 25 have a shape in which the curvature is continuous throughout the entire second surface 28 and surface 25a. Surface 25a intersects the first connecting portion 8 at an acute angle in this cross-section. The angle formed by surface 25a and the first connecting portion 8 (the angle of the inner side formed by surface 25a and the first connecting portion 8) is, for example, about 45 degrees or less. Even in this fourth variation, as in the above embodiment, it is possible to achieve low resistance of the first wiring 21 provided on the first connecting portion 8 and to suppress metal fatigue, thereby improving reliability. Furthermore, stress concentration at the boundary between the second surface 28 and surface 25a can be suppressed, further improving reliability.

[0083] In the above embodiment, the wiring provided on each of the second connection portions 7 (hereinafter referred to as the third wiring) can also be configured in the same way as the first wiring 21. In this case, the third wiring is configured, for example, as the portion of wirings 14a and 14b located on the second connection portion 7, and the portion of second wirings 31A and 31B located on the second connection portion 7, and is electrically connected to wirings 14a and 14b or second wirings 31A and 31B. The third wiring has a second main body portion made of a metallic material with a Vickers hardness of 50 HV or higher. As the metallic material constituting the third wiring, materials listed as first metallic materials can be used. The second main body portion of the third wiring includes a third surface facing the second connection portion 7 and a fourth surface other than the third surface. The fourth surface has a shape in which the curvature is continuous throughout the fourth surface in a cross section perpendicular to the extension direction of the third wiring. According to such a variation, with respect to the third wiring provided on the second connection portion 7, it is also possible to achieve low resistance and suppression of metal fatigue, and improve reliability. Furthermore, in the third wiring, similarly to the first wiring 21, "the section perpendicular to the extension direction of the third wiring" refers to the section perpendicular to the extension direction of each of the multiple portions extending in different directions in which the third wiring has such portions. For example, the extension direction of the third wiring on the straight portion 7a is along the direction of the straight portion 7a. The extension direction of the third wiring on the straight folded portion 7b is along the direction of the folded portion 7b. The extension direction of the third wiring on the R-shaped folded portion 7b is along the direction (circumferential direction) of the folded portion 7b.

[0084] Actuator device 1 can also be an actuator device other than driving mirror 2. The shape of mirror 2 is not limited to a circular shape. Mirror 2 can also be, for example, rectangular, rhomboid, or elliptical. In the above embodiment, the shaking (driving) of mirror 2 is performed by electromagnetic force, but it can also be performed by a piezoelectric element. In this case, instead of coils 11 and 12, wiring for applying voltage to the piezoelectric element is provided. Magnetic field generating part 3 can also be omitted. The first axis X1 and the second axis X2 do not have to be orthogonal, as long as they intersect each other. Actuator device 1 can also be an actuator device that shakes only around the first axis X1. In this case, frame part 4 and second connecting part 7 can be omitted, and electrodes for electrical connection with control circuitry, etc., can be provided in support part 5.

[0085] The first wiring 21 may also omit the second portion 23 and the third portion 24, and the first wiring 21 may be formed in a straight line. The second surface 28 may omit the flat portion 28a, and may, for example, have a curved shape throughout. Each second connecting portion 7 may also be formed in a straight line. The seed layer 25 may also be made of a metal material with a Vickers hardness of less than 50 HV. The curvature of the second surface 28 of the first main body portion 26 and the surface 25a of the seed layer 25 at their respective boundary portions in a cross section perpendicular to the extending direction of the first portion 22 may also be discontinuous. For the third wiring, similarly to the first wiring 21, it may also have a seed layer disposed on the second connecting portion 7 and a second main body portion disposed on the seed layer. In this case, at least the second main body portion may also be made of a metal material with a resistivity lower than that of the metal material constituting the first main body portion 26 of the first wiring 21, and / or a metal material with a Vickers hardness of 50 HV or higher.

[0086] In the above embodiments, an electromotive force monitoring coil (sensing coil) for measuring electromotive force, or a temperature sensor coil (sensing coil) for measuring temperature, may also be provided in the movable part 6. The sensing coil may also be configured in the same manner as the first wiring 21 and electrically connected to the first wiring provided on the first connecting part 8. Alternatively, in the above embodiments, the coil 12 may be used not only as a driving coil for driving the movable part 6, but also as a sensing coil. The coil 12 may also be used only as a sensing coil and not as a driving coil. Similarly, the sensing coil may be provided in the support part 5 and electrically connected to the third wiring provided on the second connecting part 7, and the coil 11 may be used not only as a driving coil but also as a sensing coil.

[0087] Explanation of symbols

[0088] 1…Actuator device, 5…Support part, 6…Modible part, 7…Second connecting part, 8…First connecting part, 8b…Diffusion layer, 21…First wiring, 25…Seed layer, 25a…Surface, 26…First main body part, 27…First surface, 28…Second surface, 28b…Bent part, 31A…Second wiring, 41…Barrier layer, X1…First axis, X2…Second axis.

Claims

1. An actuator device, characterized in that: have: Support section; Movable parts; The first connecting part connects the movable part to the support part on the first axis in such a way that the movable part can rock around the first axis; as well as The first wiring is disposed on the first connection portion. The first wiring has a first main body made of a metallic material with a Vickers hardness of 50 HV or higher. The first main body includes a first surface facing the first connecting portion and a second surface other than the first surface. The second surface has a pair of curved portions in a cross section perpendicular to the extension direction of the first wiring, which are curved in a manner that protrudes toward the first connection portion. The pair of curved portions are disposed on both sides of the first main body portion in a direction perpendicular to the extension direction of the first wiring in a cross section perpendicular to the extension direction of the first wiring.

2. The actuator device as claimed in claim 1, characterized in that: The second surface intersects the first surface at an acute angle in a cross section perpendicular to the extension direction of the first wiring.

3. The actuator device as described in claim 1 or 2, characterized in that: The second surface intersects the first surface at an angle of less than 45 degrees in a cross section perpendicular to the extension direction of the first wiring.

4. The actuator device according to any one of claims 1 to 3, characterized in that: The second surface has a plurality of the curved portions in a cross section perpendicular to the extension direction of the first wiring.

5. The actuator device according to any one of claims 1 to 4, characterized in that: The second surface has a flat portion and a pair of curved portions formed on both sides of the flat portion in a cross section perpendicular to the extension direction of the first wiring.

6. The actuator device according to any one of claims 1 to 5, characterized in that: The first connection portion is made of semiconductor material, and a diffusion layer containing impurities is formed in the first connection portion in such a way as to contact the first wiring.

7. The actuator device according to any one of claims 1 to 6, characterized in that: The first main body is composed of at least one of tungsten, titanium, nickel, molybdenum, aluminum alloy, tungsten alloy, titanium alloy, nickel alloy and stainless steel.

8. The actuator device according to any one of claims 1 to 7, characterized in that: The first wiring also has a seed layer disposed between the first connection portion and the first main body portion.

9. The actuator device as claimed in claim 8, characterized in that: The seed layer is made of a metallic material with a Vickers hardness of 50HV or higher.

10. The actuator device according to any one of claims 1 to 9, characterized in that: It further includes: a barrier layer disposed between the first connection portion and the first wiring.

11. The actuator device as claimed in claim 10, characterized in that: The barrier layer is made of a material with a Vickers hardness of 50 HV or higher.

12. The actuator device according to any one of claims 1 to 11, characterized in that: It further includes: a second wiring, which is disposed on the support portion and connected to the first wiring. The second wiring is made of a metal material with a Vickers hardness of less than 50 HV.

13. The actuator device according to any one of claims 1 to 12, characterized in that: Further features include: The frame portion supports the supporting portion and the movable portion; The second connecting part connects the support part to the frame part on the second axis in such a way that the support part can sway around the second axis that intersects the first axis. as well as The third wiring is installed on the second connection part. The third wiring has a second main body, which is made of a metal material with a lower resistivity than the metal material constituting the first main body.

14. The actuator device according to any one of claims 1 to 13, characterized in that: Further features include: The frame portion supports the supporting portion and the movable portion; The second connecting part connects the support part to the frame part on the second axis in such a way that the support part can sway around the second axis that intersects the first axis. as well as The third wiring is installed on the second connection part. The third wiring includes: a second main body, which is made of a metallic material with a Vickers hardness of 50 HV or higher. The second main body includes: a third surface facing the second connecting portion and a fourth surface other than the third surface. The fourth surface has a curved portion in a cross section perpendicular to the extension direction of the third wiring, which bends toward the second connection portion.

15. The actuator device according to any one of claims 1 to 14, characterized in that: It further includes a mirror disposed on the movable part.

16. The actuator device according to any one of claims 1 to 15, characterized in that: It further includes an insulating layer disposed on the first connection portion in a manner that rests on the first wiring wire. The surface of the insulating layer opposite to the first connection portion has a curved portion in a cross section perpendicular to the extension direction of the first wiring, which bends toward the first connection portion.

17. The actuator device according to any one of claims 1 to 16, characterized in that: It further includes an insulating layer disposed on the first connection portion in a manner that rests on the first wiring wire. The surface of the insulating layer opposite to the first connection portion has a shape with continuous curvature across the entire surface in a cross section perpendicular to the extension direction of the first wiring.

18. The actuator device according to any one of claims 1 to 17, characterized in that: Furthermore, it includes: a fourth wiring, which is disposed on the movable part and electrically connected to the first wiring. The fourth wiring is made of a metallic material with a Vickers hardness of less than 50 HV.

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