Drive element and light deflection element

Abstract

The purpose of the present invention is to provide a drive element and a light deflection element capable of suppressing damage to a support section due to stress concentration caused by torsion of the support section. This drive element (1) is provided with: a movable part (30) that is rotatable with respect to a rotation axis (R0); fixing parts (13, 23); support parts (11, 21) which extend along the rotation axis (R0) and which connect the movable part (30) and the fixed parts (13, 23); and a drive unit (12, 22) that rotates the movable unit (30) with respect to the rotation axis (R0). A plurality of recesses extending in the direction away from the movable part (30) are arranged in the thickness direction of the support parts (11, 21) and are formed on the side surfaces of the support parts (11, 21). The size of a recess formed in a first region including at least the center in the thickness direction of the side surface of the support section (11, 21) is smaller than the size of a recess formed in a second region other than the first region of the side surface of the support section (11, 21).

Description

Technical Field

[0001] The present disclosure relates to a driving element that rotates a movable portion relative to a rotation axis and a light deflecting element using the driving element. Background Art

[0002] In recent years, actuators that use MEMS (Micro Electro Mechanical System) technology to rotate a movable part have been developed. By configuring a reflective surface on the movable part, these actuators can cause light incident on the reflective surface to scan at a predetermined swing angle. For example, these actuators are used in image display devices such as head-up displays and head-mounted displays. They can also be used in laser radars, which use lasers to detect objects.

[0003] As such a driving element, one known method utilizes a so-called tuning fork vibrator to rotate a movable portion. In this driving element, the movable portion is rotatably supported by a support portion extending along the rotation axis. By driving the tuning fork vibrator, the support portion rotates, and the movable portion rotates relative to the rotation axis. This causes the reflective surface disposed on the movable portion to rotate. A driving element with such a structure is described, for example, in Patent Document 1 below.

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: International Publication No. 2013 / 046612 Summary of the Invention

[0007] In the driving element having the above structure, the outer shape of the driving element is formed by etching the substrate using the Bosch process, for example. In this case, a plurality of fan-shaped bends (concave portions) are formed on the side surface of the etched driving element and arranged in the thickness direction of the substrate.

[0008] On the other hand, in the driving element of the above structure, when the tuning fork-type vibrator drives the movable part, torsion occurs in the support part. As a result, stress concentration occurs on the side surface of the support part near the center in the thickness direction. Therefore, if a fan-shaped bend (concave portion) is formed on the side surface of the support part as described above, there is a concern that the stress concentration may cause damage starting from the fan-shaped bend (concave portion) near the center of the side surface.

[0009] In view of this problem, an object of the present disclosure is to provide a driving element capable of suppressing damage to a support portion due to stress concentration caused by torsion of the support portion, and a light deflection element using the driving element.

[0010] The first embodiment of the present disclosure relates to a driving element. The driving element of this embodiment comprises: a movable part that can rotate relative to a rotation axis; a fixed part; a support part that extends along the rotation axis and connects the movable part and the fixed part; and a driving part that rotates the movable part relative to the rotation axis. A plurality of recesses extending in a direction away from the movable part are arranged along the thickness direction of the support part and are formed on the side surface of the support part. The size of the recess formed in the first area of ​​the side surface of the support part, including at least the center in the thickness direction, is smaller than the size of the recess formed in the second area of ​​the side surface of the support part other than the first area.

[0011] When the support portion is twisted due to the rotation of the movable part, stress concentrates near the center of the side surface of the support portion. In this case, if the size of the recess formed in the side surface of the support portion is large, there is a concern that damage may occur near the center of the side surface starting from the recess. In contrast, according to the driving element of this embodiment, the size of the recess formed in the first region, including the center where stress is most concentrated when the support portion is twisted, is smaller than the size of the recess formed in the second region outside the first region. This improves the strength near the center and can suppress damage to the side surface of the support portion caused by stress concentration.

[0012] A second aspect of the present disclosure relates to a light deflection element. The light deflection element of this aspect includes the driving element according to the first aspect and a reflecting surface disposed on the movable portion.

[0013] According to the light deflection element of this aspect, light can be deflected and scanned using the reflective surface.

[0014] As described above, according to the driving element and the light deflection element of the present disclosure, it is possible to provide a driving element and a light deflection element capable of suppressing damage to the support portion due to stress concentration caused by torsion of the support portion. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is a perspective view schematically showing the structure of a driving element according to the embodiment.

[0016] Figure 2A It is a diagram schematically showing the procedure for forming a base material of a driving element according to the embodiment.

[0017] Figure 2B It is a diagram schematically showing the procedure for forming a base material of a driving element according to the embodiment.

[0018] Figure 2C It is a diagram schematically showing the procedure for forming a base material of a driving element according to the embodiment.

[0019] Figure 3 This is a diagram schematically showing a cross section of a support portion of a comparative example taken along a plane parallel to the XZ plane.

[0020] Figure 4 This is a diagram schematically showing a cross section of the support portion when it is cut along a plane parallel to the XZ plane according to the embodiment.

[0021] Figure 5A This is a schematic diagram showing an example of the correspondence between the size of the recessed portion formed on the side surface and the depth of the recessed portion according to the embodiment.

[0022] Figure 5B This is a schematic diagram showing an example of the correspondence between the size of the recessed portion formed on the side surface and the height of the recessed portion according to the embodiment.

[0023] Figure 6 This is a diagram schematically showing a cross section of the support portion according to the first modification example, taken along a plane parallel to the XZ plane.

[0024] Figure 7 This is a diagram schematically showing a cross section of the support portion according to the second modification example, taken along a plane parallel to the XZ plane.

[0025] Figure 8 It is a diagram schematically showing a cross section of the support portion according to the third modification example, taken along a plane parallel to the XZ plane.

[0026] Figure 9 It is a perspective view schematically showing the structure of a driving element according to another modified example. DETAILED DESCRIPTION

[0027] The effects and significance of the present disclosure will become more apparent through the description of the following embodiments. However, the following embodiments are merely examples of implementing the technical concept of the present disclosure, and the present disclosure is not limited to the following embodiments.

[0028] Hereinafter, embodiments of the present disclosure will be described with reference to the accompanying drawings.

[0029] In the following embodiments, a reflective surface is arranged on the movable part of the driving element to form a light deflecting element. For convenience, mutually orthogonal X-axis, Y-axis, and Z-axis are annotated in each figure. The Y-axis direction is a direction parallel to the rotation axis of the driving element, and the Z-axis direction is a direction perpendicular to the reflective surface arranged on the movable part. In addition, hereinafter, "up" refers to the positive direction of the Z-axis, and "down" refers to the negative direction of the Z-axis. "Upside" refers to the situation where it is located in the positive direction of the Z-axis when a certain point is used as a reference, and "downside" refers to the situation where it is located in the negative direction of the Z-axis when a certain point is used as a reference. "Upper surface" refers to the surface facing the positive direction of the Z-axis, and "lower surface" refers to the surface facing the negative direction of the Z-axis.

[0030] Figure 1 It is a perspective view schematically showing the structure of the driving element 1 .

[0031] The driving element 1 includes a first driving body 10, a second driving body 20, and a movable portion 30. A reflective surface 40 is provided on the upper surface of the movable portion 30, thereby forming the light deflection element 2. The driving element 1 has a shape that is symmetrical in the X-axis and Y-axis directions when viewed from above.

[0032] The first driving body 10 and the second driving body 20 rotate the movable portion 30 relative to the rotation axis R0 using a drive signal supplied from a drive circuit (not shown). The reflective surface 40 reflects light incident from above the movable portion 30 in a direction corresponding to the swing angle of the movable portion 30. As a result, light (e.g., laser light) incident on the reflective surface 40 is deflected and scanned as the movable portion 30 rotates. The movable portion 30 and the reflective surface 40 may also be formed from the same member.

[0033] The first driving body 10 includes a supporting portion 11 , a driving portion 12 , and a fixing portion 13 .

[0034] The support portion 11 supports the driving portion 12. The support portion 11 includes a first support portion 11a and a second support portion 11b.

[0035] The first support portion 11a extends along the rotation axis R0, with one end (the end on the negative side of the Y axis) connected to the movable portion 30 and the other end (the end on the positive side of the Y axis) connected to the second support portion 11b. The first support portion 11a has a rod-like (beam-like) shape. The cross-section when the center of the first support portion 11a is cut using the XZ plane is approximately square. The second support portion 11b extends along the rotation axis R0, with one end (the end on the negative side of the Y axis) connected to the other end (the end on the positive side of the Y axis) of the first support portion 11a, and the other end (the end on the positive side of the Y axis) connected to the fixed portion 13. The second support portion 11b has a plate-like shape.

[0036] The driving unit 12 rotates the movable unit 30 about the rotation axis R0. The driving unit 12 includes a pair of arm portions 12a symmetrically arranged with the rotation axis R0 interposed therebetween, and a piezoelectric driving unit 12b arranged on the arm portions 12a.

[0037] The arm portion 12a is L-shaped, formed by combining a portion extending in the Y-axis direction and a portion extending in the X-axis direction. The end of the portion extending in the X-axis direction of the arm portion 12a is connected to the support portion 11. The piezoelectric drive portion 12b is formed on the upper surface of the arm portion 12a. The piezoelectric drive portion 12b drives the arm portion 12a on which it is mounted.

[0038] The fixing portion 13 is used to fix the driving element 1 to the installation surface. The thickness of the fixing portion 13 is greater than the thickness of the support portion 11. The lower surface of the fixing portion 13 is provided on the installation surface.

[0039] The second driving body 20 includes a supporting portion 21 , a driving portion 22 , and a fixing portion 23 .

[0040] The structure of the second driving body 20 is the same as that of the first driving body 10. The first driving body 10 and the second driving body 20 are arranged opposite to each other with the movable part 30 interposed therebetween. The supporting part 11 of the first driving body 10 and the supporting part 21 of the second driving body 20 are respectively connected to the movable part 30. Figure 1 As shown, the side 11c located at the outer edge of the support portion 11 and the side 21c located at the outer edge of the support portion 21 are parallel to the rotation axis R0. Figure 1 As shown, the side 11d of the second supporting portion 11b and the side 21d of the second supporting portion 21b are parallel to the rotation axis R0.

[0041] Alternatively, the fixed portion 13 of the first driving body 10 and the fixed portion 23 of the second driving body 20 may be connected to each other to form a frame. In this case, the supporting portions 11 and 21, the driving portions 12 and 22, the movable portion 30, and the reflecting surface 40 are positioned within the frame of the fixed portions 13 and 23.

[0042] A tuning fork vibrator is formed by a pair of arm portions 12a. Furthermore, a tuning fork vibrator is formed by a pair of arm portions 22a. In the first driving body 10, the pair of arm portions 12a are driven by the two piezoelectric driving portions 12b, thereby rotating the support portion 11 relative to the rotation axis R0. Furthermore, in the second driving body 20, the pair of arm portions 22a are driven by the two piezoelectric driving portions 22b, thereby rotating the support portion 21 relative to the rotation axis R0. By controlling the support portions 11 and 21 so that their rotation directions are the same, the movable portion 30 rotates.

[0043] The piezoelectric drive unit 12b has a stacked structure in which electrode layers are respectively arranged on the upper surface and lower surface of a piezoelectric thin film 51 of a predetermined thickness. The piezoelectric drive unit 22b has a stacked structure in which electrode layers are respectively arranged on the upper surface and lower surface of a piezoelectric thin film 61 of a predetermined thickness. The piezoelectric thin film 51 and the piezoelectric thin film 61 are formed of a piezoelectric material having a high piezoelectric constant, such as lead zirconate titanate (PZT). The electrodes are formed of a material having low electrical resistance and high heat resistance, such as platinum (Pt) and gold (Au). A layer structure including the piezoelectric thin film 51 and upper and lower electrodes is formed on the upper surface of the arm 12a by sputtering, etc., whereby the piezoelectric drive unit 12b is arranged on the upper surface of the arm 12a. In addition, a layer structure including the piezoelectric thin film 61 and upper and lower electrodes is formed on the upper surface of the arm 22a by sputtering, etc., whereby the piezoelectric drive unit 22b is arranged on the upper surface of the arm 22a.

[0044] The substrate of the driving element 1 has the same profile as the driving element 1 when viewed from above and has a constant thickness. The piezoelectric driving portion 12b, the piezoelectric driving portion 22b and the reflecting surface 40 are arranged in corresponding areas on the upper surface of the substrate. In addition, a layer 13a formed of a predetermined material is formed on the lower surface of the fixed portion 13 of the substrate, and the thickness of the fixed portion 13 is relatively large. A layer 23a formed of a predetermined material is also formed on the lower surface of the fixed portion 23 of the substrate, and the thickness of the fixed portion 23 is relatively large. Therefore, the thickness of the driving element 1 is constant except for the areas where the layers 13a and 23a are formed. The materials of the layers 13a and 23a may be different from those of the substrate, or may be the same as those of the substrate.

[0045] The substrate of the driving element 1 is formed integrally of silicon (Si), for example. However, the material constituting the substrate is not limited to silicon, and may be other materials. The material constituting the substrate is preferably a material having a large mechanical strength and Young's modulus, such as metal, crystal, glass, or resin. As such a material, in addition to silicon, titanium, stainless steel, Ailinvar alloy, brass alloy, etc. can also be used. The material of the layer 13a of the fixing portion 13 and the layer 23a of the fixing portion 23 are also the same.

[0046] Figure 2A 、 Figure 2B and Figure 2C It is a diagram schematically showing the procedure for forming the base material of the driving element 1 . Figures 2A to 2C A cross section of the driving element 1 based on the XZ plane is shown.

[0047] like Figure 2AAs shown, the base material of the driver element 1 is formed by processing an SOI (Silicon On Insulator) substrate 100. SOI substrate 100 has a structure in which a device layer 101, an oxide film layer 102, and a handling layer 103 are stacked in this order from the top. Device layer 101 and handling layer 103 are made of silicon (Si), and oxide film layer 102 is made of silicon dioxide (SiO2).

[0048] like Figure 2B As shown, the device layer 101 is etched from the upper surface so as to have the same contour as the driver element 1 when viewed from above, thereby removing unnecessary portions of the device layer 101. Thus, the device layer 101 remains within the same contour as the driver element 1, and the upper surface 210 and side surfaces 220 are formed on the device layer 101.

[0049] from Figure 2B The process layer 103 is etched from the bottom surface so as to have the same outline as the fixing portion 13 and the fixing portion 23 when viewed from above, and the process layer 103 is removed. Furthermore, the oxide film layer 102 is etched from the bottom surface so as to have the same outline as the fixing portion 13 and the fixing portion 23 when viewed from above, and the oxide film layer 102 is removed. Figure 2C As shown, the handle layer 103 and the oxide film layer 102 are removed from the regions other than the fixing portions 13 and 23, and the lower surface 230 is formed on the device layer 101 other than the fixing portions 13 and 23. On the other hand, the handle layer 103 and the oxide film layer 102 are not removed from the regions of the fixing portions 13 and 23. Therefore, as described above, the thickness of the fixing portions 13 and 23 is greater.

[0050] In this embodiment, Figure 2C The side surface 220 of the device layer 101 shown is formed by etching using the Bosch process. In the Bosch process, etching steps are repeated to form multiple recessed portions (scalloped) in the device layer 101. These recessed portions extend horizontally and are arranged along the thickness of the device layer 101. These recessed portions are formed on the side surface 220 of the device layer 101.

[0051] However, according to the investigation of the inventors, it is known that when the support portion 11 or the support portion 21 is twisted due to the rotation of the movable portion 30, stress is concentrated near the center of the side surface 220 of the support portion 11 or the side surface 220 of the support portion 21 in the thickness direction. If such stress concentration occurs, there is a concern that if the recess formed on the side surface 220 of the support portion 11 or the side surface 220 of the support portion 21 is large, breakage may occur starting from the recess near the center of the side surface 220 of the support portion 11 or the side surface 220 of the support portion 21. Figure 3The comparative example of illustrates this phenomenon.

[0052] Figure 3 It is a diagram schematically showing a cross section of the support portion 11 or the support portion 21 according to a comparative example when the support portion 11 or the support portion 21 is cut along a plane parallel to the XZ plane.

[0053] like Figure 3 As shown, in the support portion 11 and the support portion 21 of the comparative example, by referring to Figures 2A to 2C The upper surface 210, the side surface 220, and the lower surface 230 are formed in the order described. By forming the side surface 220 using the Bosch process, a plurality of recesses 220a are formed on the side surface 220 in a manner arranged along the thickness direction (Z-axis direction). One recess corresponds to one etching step. Each recess 220a is recessed toward the inner side of the support portion 11 and the interior of the support portion 21. In addition, the direction in which the plurality of recesses 220a are arranged in the XZ plane is inclined relative to the Z-axis direction so as to approach the inner side as it moves downward. The inclination angle (taper angle) between the two side surfaces 220 is θ0.

[0054] When the concave portion 220a has a certain size as in the comparative example, there is a concern that Figure 3 As indicated by the white arrows, when stress concentrates near the center of the side surface 220 in the thickness direction, damage occurs in the support portion 11 or the support portion 21 starting from the concave portion 220 a near the center.

[0055] In contrast, in the embodiment, etching based on the Bosch process is performed so that the size of the recess formed in the first region, including the center where stress is most concentrated when the support portion 11 or the support portion 21 is twisted, is smaller than the size of the recess formed in the second region outside the first region. This can improve the strength of the side surface 220 near the center of the support portion 11 or the support portion 21, and can suppress damage to the side surface 220 of the support portion 11 or the support portion 21 caused by stress concentration. Figure 4 The structure and effects of the embodiment will be described.

[0056] Figure 4 It is a diagram schematically showing a cross section of the support portion 11 or the support portion 21 according to the embodiment when the support portion 11 or the support portion 21 is cut along a plane parallel to the XZ plane.

[0057] like Figure 4 As shown, in the embodiment of the support portion 11 and the support portion 21, by referring to Figures 2A to 2CThe upper surface 210, the side surface 220, and the lower surface 230 are formed in the order described. By forming the side surface 220 using the Bosch process, a plurality of recesses 221 and a plurality of recesses 222 are formed on the side surface 220 along the thickness direction (Z-axis direction). The plurality of recesses 221 and the plurality of recesses 222 formed on the side surface 220 are recessed toward the interior of the support portion 11 and the interior of the support portion 21, respectively, and have an arc shape when viewed from the Y-axis direction. In other words, each recess 221 and each recess 222 has a cylindrical side shape extending parallel to the direction away from the movable portion 30, specifically, a cylindrical side shape extending parallel to the rotation axis R0.

[0058] In the embodiment, etching using the Bosch process is performed so that the size of the recess 221 formed in the first region R1, including the center in the thickness direction of the side surface of the support portion, is smaller than the size of the recess 222 formed in the second region R2 outside the first region R1. The second region R2 is a region that combines regions above and below the first region R1.

[0059] Furthermore, the direction in which the plurality of recesses 221 and the plurality of recesses 222 are arranged in the XZ plane is inclined relative to the Z-axis direction, approaching the inner side as the recesses progress downward. The inclination angle (taper angle) between the two side surfaces 220 of the first region R1 is θ1, and the inclination angle (taper angle) between the two side surfaces 220 of the second region R2 is θ2. As described above, when etching is performed using the Bosch process so that the recesses 221 in the first region R1 are smaller than the recesses 222 in the second region R2, the taper angle θ1 is smaller than the taper angle θ2.

[0060] When the concave portion 221 near the center is formed smaller as described above, the strength near the center can be improved. Figure 4 As indicated by the white arrows, the stress is concentrated near the center of the side surface 220 in the thickness direction, and the occurrence of damage to the support portion 11 or the support portion 21 starting from the concave portion 221 near the center can be suppressed.

[0061] Figure 5A This is a schematic diagram showing an example of the correspondence between the size of the recessed portion formed on the side surface and the depth of the recessed portion according to the embodiment. Figure 5B This is a schematic diagram showing an example of the correspondence between the size of the recessed portion formed on the side surface and the height of the recessed portion according to the embodiment.

[0062] like Figure 5A As shown in FIG. 2 , the size of the recess formed on the side surface 220 may also correspond to the depth of the recess (radius or diameter of the arc portion). Figure 5BAs shown, the size of the recess formed on the side surface 220 may also correspond to the height of the recess. In etching based on the Bosch process, a larger recess can be formed by increasing the etching amount per etching step, and a smaller recess can be formed by reducing the etching amount.

[0063] To change the etching amount, for example, the speed (etching rate) of forming one recess is changed. By making the etching rate in the first region R1 smaller than the etching rate in the second region R2, the recess 221 can be formed smaller than the recess 222.

[0064] The Bosch process is plasma etching, in which ions are injected into the device layer 101. The etching intensity is determined by the high-frequency power used to control the ion irradiation energy, thereby determining the size of the recess formed in the side surface 220. Therefore, by making the high-frequency power used to form the first region R1 smaller than the high-frequency power used to form the second region R2, the recess 221 can be made smaller than the recess 222.

[0065] Furthermore, if foreign matter (particles, etc.) adheres to the processed surface during etching, the foreign matter acts as a mask, preventing proper processing of the device layer 101 and resulting in needle-shaped Si residue. In contrast, when a higher-frequency power is applied to the second region R2 than in the first region R1, as described above, the ions incident on the processed surface of the second region R2 are accelerated, making it easier to remove foreign matter adhering to the processed surface. Consequently, since Si residue can be reduced in the second region R2, the formation of defective driver elements 1 can be suppressed.

[0066] <Effects of Implementation>

[0067] According to the embodiment, the following effects can be achieved.

[0068] like Figure 4 As shown, a plurality of recesses 221 and a plurality of recesses 222 extending parallel to the rotation axis R0 are arranged in the thickness direction of the support portion 11 and the support portion 21, and are formed on the side surface 220 of the support portion 11 and the side surface 220 of the support portion 21. The size of the recesses 221 formed in the first region R1 including at least the center in the thickness direction is smaller than the size of the recesses 222 formed in the second region R2 outside the first region R1.

[0069] When the support portion 11 or the support portion 21 is twisted due to the rotation of the movable portion 30, stress is concentrated near the center of the side surface 220 of the support portion 11 or the support portion 21. Figure 3As in the comparative example shown in FIG, if the size of the recessed portion 220a formed on the side surface 220 of the support portion 11 and the side surface 220 of the support portion 21 is large, breakage will occur near the center of the side surface 220 starting from the recessed portion 220a. Figure 4 As shown, the size of the recessed portion 221 formed in the first region R1, which includes the center where stress is most concentrated when the support portion 11 or the support portion 21 is twisted, is smaller than the size of the recessed portion 222 formed in the second region R2 outside the first region R1. This improves the strength near the center and prevents damage to the side surface 220 of the support portion 11 or the side surface 220 of the support portion 21 caused by stress concentration.

[0070] Here, when the SOI substrate 100 is etched using the Bosch process to form the outer shape of the driving element 1 including the support portion 11 and the support portion 21, in order to make the recess (fan-shaped bend) formed on the side 220 after etching smaller, it is necessary to reduce the etching amount of each etching step. Therefore, if the recess (fan-shaped bend) is made smaller, the number of etching cycles required to etch the device layer 101 to form the outer shape of the driving element 1 becomes more. As a result, the etching rate is reduced and the productivity of the driving element 1 is reduced. In contrast, in an embodiment, instead of forming a smaller recess 221 (fan-shaped bend) on the entire side 220, a larger recess 222 (fan-shaped bend) is formed in the second region R2 outside the first region R1. Thus, it is possible to suppress the damage caused by stress concentration near the center and to suppress the decline in the productivity of the driving element 1.

[0071] like Figure 4 As shown, the second regions R2 are arranged above and below the first region R1. The second region R2 located above the first region R1 extends to the upper ends of the side surfaces 220 of the support portion 11 and the upper ends of the side surfaces 220 of the support portion 21, while the second region R2 located below the first region R1 extends to the lower ends of the side surfaces 220 of the support portion 11 and the lower ends of the side surfaces 220 of the support portion 21.

[0072] According to this configuration, since the small recessed portion 221 (fan-shaped curvature) is formed only near the center, a decrease in productivity of the driving element 1 can be effectively suppressed.

[0073] The side surface 220 is formed using the Bosch process so that the etching rate in the first region R1 is lower than the etching rate in the second region R2 .

[0074] This configuration allows the size of the recess 221 in the first region R1 to be smaller than the size of the recess 222 in the second region R2. Furthermore, since the etching rate in the second region R2 is higher than that in the first region R1, a decrease in the productivity of the driving element 1 can be suppressed.

[0075] like Figure 1 As shown, the support portion 11 includes a first support portion 11a and a second support portion 11b, and the drive portion 12 includes a pair of arm portions 12a arranged across the rotation axis R0 and connected to the support portion 11, and a piezoelectric drive portion 12b arranged on the arm portions 12a. Similarly, the support portion 21 includes a first support portion 21a and a second support portion 21b, and the drive portion 22 includes a pair of arm portions 22a arranged across the rotation axis R0 and connected to the support portion 21, and a piezoelectric drive portion 22b arranged on the arm portions 22a.

[0076] According to this structure, when the arm portion 12a or the arm portion 22a is driven, the first support portion 11a and the second support portion 11b, or the first support portion 21a and the second support portion 21b, are twisted. However, as described above, the recessed portion 221 (sector-shaped curvature) and recessed portion 222 (sector-shaped curvature) are formed on the side surfaces 220 of the first support portion 11a, the second support portion 11b, the first support portion 21a, and the second support portion 21b, respectively. This prevents damage to the side surfaces 220 of the first support portion 11a, the second support portion 11b, the first support portion 21a, and the second support portion 21b, respectively, caused by stress concentration.

[0077] like Figure 1 As shown, the light deflection element 2 is composed of the driving element 1 and the reflecting surface 40 disposed on the movable portion 30 .

[0078] According to this configuration, the reflective surface 40 can deflect and scan the light.

[0079] <First Modification Example>

[0080] In the above embodiment, the second region R2 is arranged above and below the first region R1 , but may be arranged only below the first region R1 .

[0081] Figure 6 It is a diagram schematically showing a cross section of the support portion 11 or the support portion 21 according to the first modification example when the support portion 11 or the support portion 21 is cut along a plane parallel to the XZ plane.

[0082] In the first modification, Figure 4 Compared to the embodiment shown, the first region R1 extends to the upper ends of the side surfaces 220 of the support portions 11 and 21, respectively, while the second region R2 extends from the lower end of the first region R1 to the lower ends of the side surfaces 220 of the support portions 11 and 21. In this case as well, a recess 221 is formed on the side surface 220 of the first region R1, and a recess 222 is formed on the side surface 220 of the second region R2, with recess 221 being smaller than recess 222. Furthermore, as described above, when etching using the Bosch process is performed so that the recess 221 in the first region R1 is smaller than the recess 222 in the second region R2, the taper angle θ1 becomes smaller than the taper angle θ2.

[0083] According to the first modified example, a smaller recess 221 (fan-shaped curvature) is formed in the first region R1 extending from the center of the side surface 220 to the upper end of each of the support portions 11 and 21. This expands the range over which damage due to stress concentration can be suppressed compared to the above-described embodiment. Consequently, damage due to stress concentration can be reliably suppressed.

[0084] <Second Modification Example>

[0085] In the above embodiment, the second region R2 is arranged above and below the first region R1 , but may be arranged only above the first region R1 .

[0086] Figure 7 It is a diagram schematically showing a cross section of the support portion 11 or the support portion 21 according to the second modification example when the support portion 11 or the support portion 21 is cut along a plane parallel to the XZ plane.

[0087] In the second modification, Figure 4 Compared to the embodiment shown, the first region R1 extends to the lower ends of the side surfaces 220 of the support portion 11 and the lower ends of the side surfaces 220 of the support portion 21, while the second region R2 extends from the upper end of the first region R1 to the upper end of the side surfaces 220 of each of the support portions 11 and 21. In this case as well, a recessed portion 221 is formed on the side surfaces 220 of the first region R1, and a recessed portion 222 is formed on the side surfaces 220 of the second region R2, with recessed portion 221 being smaller than recessed portion 222. Furthermore, as described above, when etching using the Bosch process is performed so that recessed portion 221 in the first region R1 is smaller than recessed portion 222 in the second region R2, the taper angle θ1 becomes smaller than the taper angle θ2.

[0088] According to the second modified example, since a smaller recess 221 (fan-shaped curvature) is formed in the first region R1 extending from near the center of the side surface 220 to the lower end of each of the support portions 11 and 21, the range in which damage due to stress concentration can be suppressed can be expanded compared to the above-described embodiment. Thus, damage due to stress concentration can be reliably suppressed.

[0089] <Third Modification Example>

[0090] In the above embodiment, only the second region R2 having the concave portion 222 of a constant size is arranged above the first region R1, and only the second region R2 having the concave portion 222 of a constant size is arranged below the first region R1. However, the present invention is not limited thereto, and multiple regions having concave portions of different sizes may be arranged above the first region R1, and multiple regions having concave portions of different sizes may be arranged below the first region R1.

[0091] Figure 8 It is a diagram schematically showing a cross section of the support portion 11 or the support portion 21 according to the third modification example when the support portion 11 or the support portion 21 is cut along a plane parallel to the XZ plane.

[0092] In the third modification, Figure 4 Compared to the illustrated embodiment, second regions R2 are arranged above and below first region R1, and third regions R3 are arranged above and below the upper second region R2, respectively. In each of the support portions 11 and 21, the upper second region R2 extends upward from the upper end of the first region R1, and the upper third region R3 extends from the upper end of the second region R2 to the upper end of the side surface 220. Furthermore, in each of the support portions 11 and 21, the lower second region R2 extends downward from the lower end of the first region R1, and the lower third region R3 extends from the lower end of the second region R2 to the lower end of the side surface 220.

[0093] A recess 221 is formed on the side surface 220 of the first region R1, a recess 222 is formed on the side surface 220 of the second region R2, and a recess 223 is formed on the side surface 220 of the third region R3. Recess 221 is smaller than recess 222, which in turn is smaller than recess 223. Like recesses 221 and 222, recess 223 also has a cylindrical side shape extending parallel to the direction away from the movable portion 30, specifically, parallel to the rotation axis R0. Furthermore, as described above, etching using the Bosch process is performed to achieve the respective sizes of recesses 221, 222, and 223. As a result, the taper angle θ1 of the first region R1 is smaller than the taper angle θ2 of the second region R2, and the taper angle θ2 of the second region R2 is smaller than the taper angle θ3 of the third region R3.

[0094] According to the third modified example, for each support portion of the support portion 11 and the support portion 21, the recess gradually becomes smaller from the upper end of the side surface 220 toward the center, and for each support portion of the support portion 11 and the support portion 21, the recess gradually becomes smaller from the lower end of the side surface 220 toward the center. Thus, for the support portion 11 and the support portion 21, the damage caused by the stress can be suppressed in accordance with the situation where the stress increases from the upper end and the lower end toward the center in the thickness direction. In addition, for each support portion of the support portion 11 and the support portion 21, the recess gradually becomes larger from the center of the side surface 220 toward the upper end, and for each support portion of the support portion 11 and the support portion 21, the recess gradually becomes larger from the center of the side surface 220 toward the lower end. Thus, compared with the case where all the recesses are constructed to be larger, the decline in the productivity of the driving element 1 can be effectively suppressed.

[0095] <Other Changes>

[0096] The embodiments of the present disclosure are not limited to the above-described embodiment and the above-described first to third modified examples.

[0097] In the above-described embodiment and modification, the side 11c located at the outer edge of the support portion 11 relative to the rotation axis R0 (hereinafter referred to as the side 11c of the support portion 11, or the side 11c) and the side 21c located at the outer edge of the support portion 21 relative to the rotation axis R0 (hereinafter referred to as the side 21c of the support portion 21, or the side 21c) are as shown in FIG. Figure 1 As shown, the side 11c of the support portion 11 or the side 21c of the support portion 21 is parallel to the rotation axis R0, but the side 11c of the support portion 11 or the side 21c of the support portion 21 may also have an angle relative to the rotation axis R0. For example, the side 11c of the support portion 11 and the side 21c of the support portion 21 may also be configured as follows: Figure 9 The respective sections are shown as such at an angle relative to the axis of rotation R0.

[0098] exist Figure 9 In the structure shown, Figure 1 Similarly to the embodiment shown, the side 11c near the movable portion 30 of the first support portion 11a and the side 21c near the movable portion 30 of the first support portion 21a extend parallel to the rotation axis R0. Figure 9 In the structure shown, Figure 1 Compared to the embodiment shown in FIG, the side 11c of the first support portion 11a located opposite to the movable portion 30, the side 21c of the first support portion 21a located opposite to the movable portion 30, and the side 11d of the second support portion 11b, and the side 21d of the second support portion 21b are inclined relative to the rotation axis R0 in the XY plane. Figure 9 In the structure shown, the inclination of the side 11c in the XY plane relative to the rotation axis R0 and the inclination of the side 11d in the XY plane relative to the rotation axis R0 are opposite to each other. Figure 9 In the structure shown, the inclination of the side 21c in the XY plane relative to the rotation axis R0 and the inclination of the side 21d in the XY plane relative to the rotation axis R0 are opposite to each other. When the support portion 11 and the support portion 21 are formed in this way, as in the above-mentioned embodiment and modification examples, a plurality of recesses respectively formed on the side surface of the support portion 11 and the side surface 220 of the support portion 21 extend in a direction away from the movable portion 30. In this case, as in the above-mentioned embodiment and the first to third modification examples, the recesses formed in the first region are formed to be smaller than the recesses formed in the second region outside the first region. Thus, as in the above-mentioned embodiment and the first to third modification examples, the strength near the center can be improved, and damage to the side surface 220 of the support portion 11 or the side surface 220 of the support portion 21 caused by stress concentration can be suppressed. In addition, in Figure 9In the illustrated configuration, the inclination of side 11c and side 11d relative to rotation axis R0 in the XY plane are opposite to each other. However, the inclination of side 11c and side 11d relative to rotation axis R0 in the XY plane can also be in the same direction. Similarly, the inclination of side 21c and side 21d relative to rotation axis R0 in the XY plane can also be the same.

[0099] In the above embodiment, the recess 222 of the upper second region R2 and the recess 222 of the lower second region R2 are of equal size to each other, but if the recess 221 of the first region R1 is smaller than the recess 222 of the upper and lower second regions R2, the recess 222 of the upper and lower second regions R2 may not be of equal size to each other.

[0100] For example, the concave portion 222 of the lower second region R2 may be larger than the concave portion 222 of the upper second region R2. In this case, the concave portion 222 of the lower second region R2 can be made larger than the concave portion 222 of the upper second region R2 by increasing the etching rate for the lower second region R2 relative to the etching rate for the upper second region R2 or increasing the high-frequency power for the lower second region R2 relative to the high-frequency power for the upper second region R2.

[0101] Furthermore, by making the high-frequency power applied to the lower second region R2 greater than the high-frequency power applied to the upper second region R2, foreign matter adhering to the lower second region R2 can be more easily removed. This can further reduce Si residue generated in the lower second region R2.

[0102] In the third modified example, two regions with recesses of different sizes are arranged above the central first region R1, but three or more regions with recesses of different sizes may also be arranged. Also, in the third modified example, two regions with recesses of different sizes are arranged below the central first region R1, but three or more regions with recesses of different sizes may also be arranged. In these cases as well, it is preferred that the recesses gradually increase in size upward from the first region R1, and it is also preferred that the recesses gradually increase in size downward from the first region R1.

[0103] In the above embodiment and modification examples, the region above the first region R1 and the region below the first region R1 are vertically aligned with respect to the center of the side surface 220 , but they do not necessarily need to be aligned.

[0104] In the above-described embodiment and modification, the center position of the first region R1 is located at the center position of the side surface 220 in the vertical direction, but it may be offset from the center position of the side surface 220. However, since it is considered that the stress applied to the side surface 220 is evenly distributed vertically relative to the center position of the side surface 220, it is preferable that the center position of the first region R1 is located at the center position of the side surface 220.

[0105] In the above-mentioned embodiment and modification, all side surfaces 220 of the support portion 11 and the support portion 21 are applied. Figure 4 、 Figure 6 、 Figure 7 or Figure 8 However, it is also possible to apply only the first support portion 11a in the support portion 11 and the first support portion 21a in the support portion 21. Figure 4 、 Figure 6 、 Figure 7 or Figure 8 The reason is that the stress concentration caused by torsion is significant in the first supporting portion 11a or the first supporting portion 21a. However, if the first supporting portion 11a and the second supporting portion 11b are etched independently based on the Bosch process with different settings, and the first supporting portion 21a and the second supporting portion 21b are etched independently based on the Bosch process with different settings, the manufacturing sequence becomes complicated. Therefore, it is preferable to apply the Bosch process to all side surfaces 220 of the supporting portion 11 and the supporting portion 21. Figure 4 、 Figure 6 、 Figure 7 or Figure 8 The structure is further applied to all sides 220 of the driving element 1. Figure 4 、 Figure 6 、 Figure 7 or Figure 8 structure.

[0106] In the above-mentioned embodiment and modification, the side surfaces 220 of the support portion 11 and the support portion 21 of the driving element 1 are applied. Figure 4 、 Figure 6 、 Figure 7 or Figure 8 The structure is not limited to the structure of the above, but it can also be applied to DMD (Digital Micromirror Device) which is one of the MEMS devices. In DMD, since the support part (torsion hinge) connected to the reflector is driven and twisted, the stress is concentrated near the center of the thickness direction of the side of the support part. Therefore, when the side of the support part is formed by etching using the Bosch process, by applying Figure 4 、 Figure 6 、 Figure 7 or Figure 8structure, thereby improving the strength near the center, thereby suppressing damage to the side of the DMD support portion caused by stress concentration.

[0107] In the above-described embodiment and modified examples, the driving element 1 is used as the light deflection element 2. However, the driving element 1 may be used as an element other than the light deflection element. When the driving element 1 is used as an element other than the light deflection element, the reflective surface 40 may not be provided on the movable portion 30, or a member other than the reflective surface 40 may be provided.

[0108] Furthermore, the embodiments of the present disclosure can be variously modified as appropriate within the scope of the technical concept shown in the claims.

[0109] (Note)

[0110] The following technology is disclosed through the description of the above embodiments.

[0111] (Technique 1)

[0112] A driving element comprising:

[0113] a movable portion rotatable relative to the rotation axis;

[0114] Fixed part;

[0115] a supporting portion extending along the rotation axis and connecting the movable portion and the fixed portion; and

[0116] a driving portion that rotates the movable portion relative to the rotation axis,

[0117] A plurality of recessed portions extending in a direction away from the movable portion are arranged in a thickness direction of the support portion and formed on a side surface of the support portion.

[0118] The size of the recessed portion formed in a first region of the side surface of the support portion including at least the center in the thickness direction is smaller than the size of the recessed portion formed in a second region of the side surface of the support portion other than the first region.

[0119] When the support portion is twisted due to the rotation of the movable portion, stress concentrates near the center of the side surface of the support portion. If the recess formed in the side surface of the support portion is large, there is a concern that damage may occur near the center of the side surface, starting from the recess. In contrast, according to the above-mentioned technology, the recess formed in the first region, including the center where stress is most concentrated when the support portion twists, is smaller than the recess formed in the second region outside the first region. This improves the strength near the center and suppresses damage to the side surface of the support portion caused by stress concentration.

[0120] (Technique 2)

[0121] In the driving element described in Technology 1,

[0122] The second area is disposed above and below the first area, respectively.

[0123] The second area on the upper side extends to the upper end of the side surface of the support portion,

[0124] The second region on the lower side extends to the lower end of the side surface of the support portion.

[0125] According to this technology, since the small recessed portion (fan-shaped curvature) is formed only near the center, it is possible to effectively suppress a decrease in the productivity of the driving element.

[0126] (Technique 3)

[0127] In the driving element described in Technology 1,

[0128] The first region extends to the upper end of the side surface of the support portion,

[0129] The second region extends from a lower end of the first region to a lower end of a side surface of the support portion.

[0130] According to this technology, since a small recess (fan-shaped curvature) is formed in the first region from the center of the side surface of the support portion to the upper end, the range in which damage caused by stress concentration can be suppressed can be expanded. As a result, damage caused by stress concentration can be reliably suppressed.

[0131] (Technique 4)

[0132] In the driving element described in Technology 1,

[0133] The first region extends to the lower end of the side surface of the support portion,

[0134] The second region extends from an upper end of the first region to an upper end of a side surface of the support portion.

[0135] According to this technology, since a small recess (fan-shaped curvature) is formed in the first region from the center of the side surface of the support portion to the lower end, the range in which damage caused by stress concentration can be suppressed can be expanded. As a result, damage caused by stress concentration can be reliably suppressed.

[0136] (Technique 5)

[0137] In the driving element described in any one of Techniques 1 to 4,

[0138] A taper angle of the side surface in the first region is smaller than a taper angle of the side surface in the second region.

[0139] (Technique 6)

[0140] In the driving element described in any one of Techniques 1 to 5,

[0141] The side surface is formed using a Bosch process so that an etching rate in the first region is lower than an etching rate in the second region.

[0142] This technique allows the size of the recess in the first region to be smaller than that in the second region. Furthermore, since the etching rate in the second region is higher than that in the first region, a decrease in the productivity of the driving element can be suppressed.

[0143] (Technique 7)

[0144] In the driving element described in any one of Techniques 1 to 6,

[0145] The support portion is made of silicon (Si).

[0146] (Technique 8)

[0147] In the driving element described in any one of Techniques 1 to 7,

[0148] The support portion comprises:

[0149] a first supporting portion, one end of which is connected to the movable portion; and

[0150] a second supporting portion, one end of which is connected to the other end of the first supporting portion, and the other end of which is connected to the fixing portion;

[0151] The driving unit includes:

[0152] a pair of arms disposed across the rotation axis and connected to the support portion; and

[0153] The piezoelectric driving portion is disposed on the arm portion.

[0154] According to this technology, when the arm portion is driven, torsion occurs in the first supporting portion and the second supporting portion, but since recesses (fan-shaped bends) are formed on the sides of the first supporting portion and the second supporting portion as described above, damage to the sides of the first supporting portion and the second supporting portion caused by stress concentration can be suppressed.

[0155] (Technique 9)

[0156] A light deflection element comprising:

[0157] The driving element described in any one of Techniques 1 to 8; and

[0158] The reflecting surface is arranged on the movable part.

[0159] According to this technology, light can be deflected and scanned using a reflective surface.

[0160] Industrial applicability

[0161] The drive element and light deflection element disclosed herein can suppress stress concentration caused by torsion in the support portion, which could lead to damage to the support portion. This improves the durability of the drive element and light deflection element. As such, the drive element and light deflection element disclosed herein are industrially useful.

[0162] Description of Reference Numerals

[0163] 1. Driving element; 2. Light deflection element; 10. First driving body; 11. Supporting portion; 11a. First supporting portion; 11b. Second supporting portion; 12. Driving portion; 12a. Arm portion; 12b. Piezoelectric driving portion; 13. Fixing portion; 20. Second driving body; 21. Supporting portion; 21a. First supporting portion; 21b. Second supporting portion; 22. Driving portion; 22a. Arm portion; 22b. Piezoelectric driving portion; 23. Fixing portion; 30. Movable portion; 40. Reflecting surface; 220. Side surface; 220a, 221, 222, 223, recessed portion; R0, rotation axis; R1, first region; R2, second region; R3, third region.

Claims

1. A driving element, wherein: The drive element has: a movable portion rotatable relative to the rotation axis; Fixed part; a supporting portion extending along the rotation axis and connecting the movable portion and the fixed portion; as well as a driving portion that rotates the movable portion relative to the rotation axis, A plurality of recessed portions extending in a direction away from the movable portion are arranged in a thickness direction of the support portion and formed on a side surface of the support portion. The size of the recessed portion formed in a first region of the side surface of the support portion including at least the center in the thickness direction is smaller than the size of the recessed portion formed in a second region of the side surface of the support portion other than the first region.

2. The driving element according to claim 1, wherein The second area is disposed above and below the first area, respectively. The second area on the upper side extends to the upper end of the side surface of the support portion, The second region on the lower side extends to the lower end of the side surface of the support portion.

3. The driving element according to claim 1, wherein The first region extends to the upper end of the side surface of the support portion, The second region extends from a lower end of the first region to a lower end of a side surface of the support portion.

4. The driving element according to claim 1, wherein The first region extends to the lower end of the side surface of the support portion, The second region extends from an upper end of the first region to an upper end of a side surface of the support portion.

5. The driving element according to claim 1, wherein A taper angle of the side surface in the first region is smaller than a taper angle of the side surface in the second region.

6. The driving element according to claim 1, wherein The side surface is formed using the Bosch process so that an etching rate in the first region is lower than an etching rate in the second region.

7. The driving element according to claim 1, wherein The support portion is made of silicon, that is, Si.

8. The driving element according to claim 1, wherein The support portion comprises: a first supporting portion, one end of which is connected to the movable portion; and a second supporting portion, one end of which is connected to the other end of the first supporting portion, and the other end of which is connected to the fixing portion; The driving unit includes: a pair of arms disposed across the rotation axis and connected to the support portion; and The piezoelectric driving portion is disposed on the arm portion.

9. A light deflection element, wherein: The light deflection element comprises: The driving element according to any one of claims 1 to 8; and The reflecting surface is arranged on the movable part.

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