Optical reflective element and method for manufacturing optical reflective element

Abstract

The optical reflection element is provided with a movable part (40) and a drive part that rotates the movable part (40) about a rotation axis (R10). In a region of an outer peripheral portion (40a) of the movable portion (40) on the substrate (101), at least a layer structure identical to a region from the piezoelectric layer (112) to an upper surface of the substrate (101) in a region of the drive portion is disposed. In a region of a central portion (40b) of the movable portion (40) on the substrate (101), a layer structure identical to a region from the lower electrode layer (111) to an upper surface of the substrate (101) in a region of the drive portion is disposed. In the area of the central part (40b), the upper surface of the lower electrode layer (111) is exposed to the outside to form a reflecting surface (41).

Description

Technical Field

[0001] The present invention relates to an optical reflection element that drives a movable part formed with a reflection surface, and a manufacturing method of the optical reflection element. Background Art

[0002] An optical reflection element that drives a movable part formed with a reflection surface is known. In such an optical reflection element, for example, a reflection surface is disposed on a movable part that rotates about a rotation axis, and a light beam incident on the reflection surface is scanned as the movable part rotates.

[0003] Patent Document 1 below describes an optical reflection element that includes: a reflector that reflects light by rotating and swinging about a rotation axis; a connecting body that is disposed along the rotation axis and connected to the reflector; and a driving body that rotates and swings the connecting body. The reflector, the connecting body, and the driving body are formed by removing unnecessary portions of a silicon substrate. A reflection portion that reflects light is disposed on the surface of the reflector. An electrode and a piezoelectric body are laminated on the surface of the driving body.

[0004] Prior Art Documents

[0005] Patent Documents

[0006] Patent Document 1: Japanese Unexamined Patent Application Publication No. 2019-82625 Summary of the Invention

[0007] Problems to be Solved by the Invention

[0008] In an optical reflection element as described above, it is preferable to be able to simply and stably dispose a highly reflective reflection surface with suppressed warping.

[0009] In view of this problem, an object of the present invention is to provide an optical reflection element and a manufacturing method of an optical reflection element that can simply and stably dispose a highly reflective reflection surface with suppressed warping.

[0010] Solutions to the Problems

[0011] The optical reflection element according to the first aspect of the present invention includes: a movable part; and a drive part that rotates the movable part around a rotation axis. In the region of the drive part on the substrate forming the contour of the optical reflection element, a lower electrode layer, an upper electrode layer located above the lower electrode layer, and a piezoelectric layer located between the lower electrode layer and the upper electrode layer are arranged. In the region of the outer peripheral part of the movable part on the substrate, at least the same layer structure as the range from the piezoelectric layer to the upper surface of the substrate in the region of the drive part is arranged. In the region of the central part of the movable part on the substrate, the same layer structure as the range from the lower electrode layer to the upper surface of the substrate in the region of the drive part is arranged. In the region of the central part, the upper surface of the lower electrode layer is exposed to the outside and constitutes a reflection surface.

[0012] According to the optical reflection element of this aspect, since the lower electrode layer is used as the reflection surface, a reflection surface with a high reflectivity can be simply formed. In addition, in the region of the outer peripheral part of the movable part, the same layer structure as the range from the piezoelectric layer to the upper surface of the substrate is arranged and the thickness becomes larger, so the warping of the reflection surface located inside the layer structure can be suppressed by this layer structure. Here, the layer structure is arranged on the upper surface of the movable part in the same manner as the reflection surface and is adjacent to the reflection surface, so the warping of the reflection surface can be effectively suppressed by the layer structure. Therefore, the reflection surface with effectively suppressed warping can be stably arranged. Thus, according to the optical reflection element of this aspect, a high-reflectivity reflection surface with suppressed warping can be simply and stably arranged.

[0013] In the manufacturing method of the optical reflection element according to the second aspect of the present invention, the lower electrode layer, the piezoelectric layer, and the upper electrode layer are sequentially formed from the substrate side, the upper electrode layer is removed so that at least the upper electrode layer remains within the range of the drive part, the lower electrode layer and the piezoelectric layer are removed so that at least the lower electrode layer and the piezoelectric layer remain within the range of the drive part and the movable part, the piezoelectric layer is removed from the movable part so that the piezoelectric layer remains in the outer peripheral part of the movable part, the upper surface of the lower electrode layer is exposed, and the part of the substrate other than the optical reflection element is removed.

[0014] According to the manufacturing method of the optical reflection element according to this embodiment, after forming a layer structure including a lower electrode layer, a piezoelectric layer, and an upper electrode layer on a substrate, these layers of the layer structure are selectively removed by an etching process, whereby a movable part and a driving part can be formed together in the same process. Thereby, device fabrication can be achieved at low cost. In this forming process, wet etching is applied to the region of the central part of the movable part to expose the lower electrode layer to the outside, whereby it is possible to suppress the formation of irregularities caused by etching on the upper surface of the lower electrode layer and suppress the reduction of the reflectivity of this upper surface. In addition, during this wet etching, at least the layer structure from the piezoelectric layer to the substrate remains in the region of the outer peripheral part of the movable part, so a resist is disposed on the upper side and the outside of this outer peripheral part. Therefore, the etching agent for the wet etching does not intrude from the outside into the boundary between the substrate and the lower electrode layer, and peeling at the outer peripheral part of the lower electrode layer can be suppressed. Therefore, it is possible to simply and stably dispose a reflection surface with reduced reflectivity reduction on the movable part.

[0015] Effects of the Invention

[0016] As described above, according to the present invention, it is possible to provide an optical reflection element and a manufacturing method of an optical reflection element capable of simply and stably disposing a highly reflective surface with suppressed warping.

[0017] The effects or significance of the present invention are further clarified by the description of the embodiments shown below. However, the embodiments shown below are merely an exemplification when implementing the present invention, and the present invention is not limited by any of the contents described in the following embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 is a plan view schematically showing the structure of the optical reflection element according to Embodiment 1.

[0019] Figure 2 (a) and (b) thereof are respectively a plan view and a cross-sectional view schematically showing the structure of the movable part according to Embodiment 1.

[0020] Figure 3 are a plan view and a cross-sectional view for explaining the formation process of the optical reflection element according to Embodiment 1.

[0021] Figure 4 are a plan view and a cross-sectional view for explaining the formation process of the optical reflection element according to Embodiment 1.

[0022] Figure 5 are a plan view and a cross-sectional view for explaining the formation process of the optical reflection element according to Embodiment 1.

[0023] Figure 6These are a top view and a cross-sectional view for explaining the formation process of the optical reflection element according to Embodiment 1.

[0024] Figure 7 These are a top view and a cross-sectional view for explaining the formation process of the optical reflection element according to Embodiment 1.

[0025] Figure 8 These are a top view and a cross-sectional view for explaining the formation process of the optical reflection element according to Embodiment 1.

[0026] Figure 9 These are a top view and a cross-sectional view for explaining the formation process of the optical reflection element according to Embodiment 1.

[0027] Figure 10 This is a diagram for explaining the problems in the case of performing dry etching according to the comparative example.

[0028] Figure 11 In (a) of [], this is a cross-sectional view for explaining the peeling of the lower electrode in the case where a resist is disposed to match the range of the lower electrode according to the comparative example. Figure 11 In (a) of [], this is a cross-sectional view for explaining the suppression of the peeling of the lower electrode in the case where a resist is disposed so as to cover the outer peripheral portion of the lower electrode according to Embodiment 1.

[0029] Figure 12 These are a top view and a cross-sectional view for explaining the formation process of the optical reflection element according to Embodiment 1.

[0030] Figure 13 These are a top view and a cross-sectional view for explaining the formation process of the optical reflection element according to Embodiment 1.

[0031] Figure 14 These are a top view and a cross-sectional view for explaining the formation process of the optical reflection element according to Embodiment 1.

[0032] Figure 15 These are a top view and a cross-sectional view for explaining the formation process of the optical reflection element according to Embodiment 1.

[0033] Figure 16 This is a flowchart showing the formation process of the optical reflection element according to Embodiment 1.

[0034] Figure 17 In (a) and (b) of [], these are a top view and a cross-sectional view schematically showing the structure of the movable part according to Modification 1 of Embodiment 1.

[0035] Figure 18(a) to (c) are cross-sectional views for explaining the formation process of the optical reflection element according to Modification 1 of Embodiment 1.

[0036] Figure 19 (a) and (b) are a top view and a cross-sectional view schematically showing the structure of the movable part according to Modification 2 of Embodiment 1, respectively.

[0037] Figure 20 (a) and (b) are a top view and a cross-sectional view schematically showing the structure of the movable part according to Modification 3 of Embodiment 1, respectively.

[0038] Figure 21 is a top view schematically showing the structure of the optical reflection element according to Embodiment 2.

[0039] However, the drawings are mainly for illustrative purposes and do not limit the scope of the present invention. Detailed Embodiments

[0040] Hereinafter, embodiments of the present invention will be described with reference to the drawings. For convenience, the mutually orthogonal X, Y, and Z axes are marked in each figure. The positive direction of the Z axis is the vertically upward direction.

[0041] <Embodiment 1>

[0042] Figure 1 is a top view schematically showing the structure of the optical reflection element 1.

[0043] The optical reflection element 1 includes a fixed part 10, a pair of vibrating parts 21, a pair of vibrating parts 22, a pair of connecting parts 31, a pair of connecting parts 32, movable parts 40, four driving parts 50, four detecting parts 60, eight wirings 80, and a pair of electrode parts 70. The optical reflection element 1 is configured to be symmetric about the center C10 in the X-axis direction and the Y-axis direction.

[0044] The fixed part 10 is configured in a frame shape. In a top view, the movable part 40 has a circular shape. The movable part 40 is supported by the fixed part 10 via a pair of vibrating parts 21 and 22. The movable part 40 is disposed at the position of the center C10 of the optical reflection element 1 and rotates about a rotation axis R10 that passes through the center C10 and extends in the X-axis direction. In a top view, the movable part 40 has a shape symmetric about the rotation axis R10.

[0045] A reflecting surface 41 for reflecting light is formed at the center of the movable part 40, and a protrusion 42 protruding in the positive Z-axis direction with respect to the reflecting surface 41 is formed on the outer periphery of the movable part 40. Regarding the layer structure of the movable part 40, it will be described later with reference to Figure 2 (a) and (b).

[0046] A pair of vibrating parts 21 and 22 and a pair of connecting parts 31 and 32 are located at an opening 11 that penetrates the fixed part 10 in the Z-axis direction at the center of the fixed part 10 when viewed from above, and the end of the connecting part 31 is supported by the fixed part 10.

[0047] When viewed from above, the vibrating parts 21 and 22 have an L shape. The vibrating parts 21 and 22 have a shape extending in the X-axis direction near the front end and a shape extending in the Y-axis direction near the connection with the connecting parts 31 and 32. The vibrating parts 21 and 22 are connected to the fixed part 10 via the connecting part 31 near the rotation axis R10 and are connected to the movable part 40 via the connecting part 32. The vibrating part 21 is arranged on the negative Y-axis side of the rotation axis R10, and the vibrating part 22 is arranged on the positive Y-axis side of the rotation axis R10. The connecting parts 31 and 32 extend in the X-axis direction along the rotation axis R10. When viewed from above, the vibrating parts 21 and 22 located on the positive X-axis side or the negative X-axis side of the movable part 40 are in the shape of a tuning fork.

[0048] The drive part 50 and the detection part 60 are arranged on the upper surface of the vibrating parts 21 and 22. The electrode part 70 is arranged on the upper surface of the fixed part 10. One electrode part 70 includes two first electrode parts 71, two second electrode parts 72, and two third electrode parts 73. The number of the third electrode parts 73 arranged in one electrode part 70 may also be one or three or more. On the upper surfaces of the first electrode part 71, the second electrode part 72, and the third electrode part 73, cables (external wirings) connected to external devices are respectively connected by wire bonding.

[0049] The drive part 50, the detection part 60, the wiring 80, the first electrode part 71, and the second electrode part 72 have a layer structure including a lower electrode layer 111, a piezoelectric layer 112, and an upper electrode layer 113, which will be described later. The region of the electrode part 70 other than the first electrode part 71, the second electrode part 72, and the third electrode part 73 has a layer structure including the lower electrode layer 111 and the piezoelectric layer 112. The third electrode part 73 has the lower electrode layer 111.

[0050] The upper electrode layers 113 of the drive part 50 and the detection part 60 are respectively connected to the upper electrode layers 113 of the first electrode part 71 and the second electrode part 72 via the upper electrode layer 113 of the wiring 80. The first electrode part 71 is connected to a power supply, a power circuit, etc. in the external device, and the second electrode part 72 is connected to a galvanometer, a current detection circuit, etc. in the external device. The lower electrode layers 111 of the drive part 50 and the detection part 60 are connected to the lower electrode layer 111 of the third electrode part 73 via the lower electrode layer 111 of the wiring 80. The third electrode part 73 is connected to the ground in the external device.

[0051] When a driving voltage is applied to the driving unit 50 via the first electrode unit 71, the piezoelectric layer 112 in the driving unit 50 deforms due to the inverse piezoelectric effect, and the vibrating units 21 and 22 provided with the driving unit 50 perform flexural vibration. When driving the optical reflection element 1, driving voltages with opposite phases are applied to the driving unit 50 of the vibrating unit 21 and the driving unit 50 of the vibrating unit 22, and driving voltages with the same phase are applied to the driving units 50 of the pair of vibrating units 21. As a result, the movable unit 40 rotates around the rotation axis R10, and the direction of the light incident on the reflection surface 41 changes corresponding to the rotation angle of the movable unit 40.

[0052] On the other hand, if the vibrating units 21 and 22 generate flexure, the detection units 60 disposed on the vibrating units 21 and 22 deform. At this time, due to the piezoelectric effect, current flows from the detection unit 60 to the second electrode unit 72 via the wiring 80. Therefore, it is possible to detect the flexure of the vibrating units 21 and 22 based on the current value detected in the external device connected to the second electrode unit 72.

[0053] Figure 2 Figs. (a) and (b) schematically show a plan view and a cross-sectional view of the structure of the movable unit 40. Figure 2 Fig. (b) is a cross-sectional view obtained by observing the cross-section C1-C2 in the plan view of Fig. (a) along the positive X-axis direction. Figure 2 of Fig. (a).

[0054] The movable unit 40 has a layer structure including a substrate 101, a lower electrode layer 111, and a piezoelectric layer 112. An adhesion layer 121 is disposed between the substrate 101 and the lower electrode layer 111 to improve the adhesion between the substrate 101 and the lower electrode layer 111. In the movable unit 40, the substrate 101 and the lower electrode layer 111 have a circular shape in a plan view, and the diameter of the lower electrode layer 111 is slightly smaller than the diameter of the substrate 101.

[0055] In the region of the outer peripheral portion 40a of the movable unit 40 on the substrate 101, a layer structure composed of the adhesion layer 121, the lower electrode layer 111, and the piezoelectric layer 112 is disposed. In the region of the central portion 40b of the movable unit 40 on the substrate 101, a layer structure composed of the adhesion layer 121 and the lower electrode layer 111 is disposed. In a plan view, the piezoelectric layer 112 of the movable unit 40 is formed in a ring shape along the outer peripheral portion of the upper surface of the lower electrode layer 111.

[0056] In the region of the central portion 40b, the upper surface of the lower electrode layer 111 is exposed to the outside to form the reflection surface 41. In the region of the outer peripheral portion 40a, the piezoelectric layer 112 protrudes from the upper surface of the lower electrode layer 111 to form a protruding portion 42.

[0057] Next, with reference to Figures 3 to 15The formation process of the optical reflection element 1 will be described with reference to the top view and cross-sectional view.

[0058] In Figures 3 to 9 and Figures 12 to 15 the structure of the region near the negative side of the X-axis and the negative side of the Y-axis located at the center C10 is schematically shown. Hereinafter, for convenience, the formation process in this region will be described.

[0059] Figures 3 to 9 and Figures 12 to 15 The figures shown in the upper layer of Figures 3 to 9 and Figures 12 to 15 are top views of the optical reflection element 1 and the structure in the middle of formation. Figures 3 to 9 and Figures 12 to 15 The figures shown in the middle layer of Figures 3 to 9 and Figures 12 to 15 are the figures obtained by observing the C1-C2 cross-section in the top view shown in the upper layer of Figures 3 to 9 and Figures 12 to 15 in the positive X-axis direction. In addition, in Figures 3 to 9 and Figures 12 to 15 in the top view of the upper layer, for convenience, the same materials as those in the cross-sectional views of the middle layer and the lower layer are shown with the same slashes.

[0060] In addition, in the following figures, for ease of explanation, the end portion of the drive unit 50 and the third electrode portion 73 are illustrated in the C3-C4 cross-section. In addition, since the detection unit 60, the wiring 80, the first electrode portion 71, and the second electrode portion 72 have the same structure as the drive unit 50, the illustration thereof is omitted for convenience.

[0061] As Figure 3 shown, a pre-processed substrate 100 in which a substrate 101, an adhesion layer 121, a lower electrode layer 111, a piezoelectric layer 112, an adhesion layer 122, and an upper electrode layer 113 are sequentially laminated upward is prepared.

[0062] The substrate 101 is made of, for example, silicon (Si). On the upper surface of the substrate 101, a thermal oxide film made of, for example, silicon dioxide (SiO2) is formed by thermal oxidation treatment. The adhesion layer 121 is disposed to improve the adhesion between the substrate 101 and the lower electrode layer 111, and is made of, for example, titanium (Ti). The lower electrode layer 111 is made of, for example, platinum (Pt). The piezoelectric layer 112 is made of, for example, a single crystal structure of PZT (lead zirconate titanate: Pb(Zr,Ti)O3). The adhesion layer 122 is disposed to improve the adhesion between the piezoelectric layer 112 and the upper electrode layer 113, and is made of the same material as the adhesion layer 121. The upper electrode layer 113 is made of, for example, gold (Au).

[0063] The upper surface of the substrate 101 is subjected to thermal oxidation treatment, and the bonding layer 121, the lower electrode layer 111, the piezoelectric layer 112, the bonding layer 122, and the upper electrode layer 113 are sequentially laminated on the substrate 101 by PVD methods represented by sputtering and evaporation, sol-gel methods, CVD methods, etc., thereby forming the pre-process substrate 100.

[0064] Next, as Figure 4 shown, a resist 131 is disposed in the region where the upper electrode layer 113 remains. Specifically, the region where the upper electrode layer 113 remains is Figure 1 the range of the driving portion 50, the detecting portion 60, the wiring 80, the first electrode portion 71, and the second electrode portion 72 shown in the top view of Figure 4 . Then, dry etching is performed on the structure of Figure 5 from above. Thus, as

[0065] shown, the upper electrode layer 113 and the bonding layer 122 in the region other than the resist 131 are removed, and then the resist 131 is removed. Figure 6 Next, as Figure 1 shown, a resist 132 is disposed in the region where the lower electrode layer 111 and the piezoelectric layer 112 remain. Specifically, the region where the lower electrode layer 111 and the piezoelectric layer 112 remain is Figure 6 the range of the movable portion 40, the driving portion 50, the detecting portion 60, the wiring 80, and the electrode portion 70 shown in the top view of Figure 7 . Then, dry etching is performed on the structure of Figure 8 from above. Thus, as

[0066] shown, the lower electrode layer 111, the piezoelectric layer 112, and the bonding layer 121 in the region other than the resist 132 are removed, and the resist 132 is removed as Figure 9 shown. Figure 1 Next, as Figure 9 shown, a resist 133 is disposed in the region other than the region where the piezoelectric layer 112 is to be removed. Specifically, the region where the piezoelectric layer 112 is to be removed is

[0067] the range of the movable portion 40 and the third electrode portion 73 shown in the top view of Figure 10 . The diameter d1 of the region where the piezoelectric layer 112 is to be removed in the movable portion 40 is smaller than the diameter d2 of the lower electrode layer 111 of the movable portion 40, and the range of the diameter d1 is located inside the range of the diameter d2. That is, the resist 133 is disposed so as to cover the outer peripheral portion of the piezoelectric layer 112 in the movable portion 40. Then, wet etching is performed on the structure of Figure 9 from above.

[0068] The piezoelectric layer 112 of Embodiment 1 is composed of a single crystal structure of PZT. Since it is very difficult to form PZT that contains only a single crystal structure, usually, even if PZT is formed in a way that contains only a single crystal structure, the PZT will contain crystal defects with abnormally grown crystals. Thus, as Figure 10 shown in the upper layer of, the piezoelectric layer 112 of Embodiment 1 also locally contains crystal defects 112a.

[0069] If dry etching is performed on such a piezoelectric layer 112 from above, due to the etching rate difference between the part composed of the single crystal structure and the part of the crystal defect 112a, as Figure 10 shown in the lower layer of, a recess 111a is formed on the upper surface of the lower electrode layer 111. If such unevenness is formed on the upper surface of the lower electrode layer 111, the reflectivity of the upper surface of the lower electrode layer 111 is significantly reduced. That is, in the case of dry etching, physical etching based on ion bombardment dominates, so selective etching of the piezoelectric layer 112 and the lower electrode layer 111 cannot be performed. As a result, the etching rate difference caused by the crystal defects in the piezoelectric layer 112 is directly reflected in the lower electrode layer 111, resulting in unevenness in the lower electrode layer 111.

[0070] In contrast, in wet etching, a large difference in the etching rate between the piezoelectric layer 112 and the lower electrode layer 111 can be set through a chemical reaction (chemical etching). Therefore, even if an etching rate difference in the piezoelectric layer 112 caused by crystal defects occurs during wet etching of the piezoelectric layer 112, the situation where this difference affects the lower electrode layer 111 is very rare.

[0071] Therefore, in Embodiment 1, wet etching is performed on the Figure 9 structure from above. Thus, when removing the piezoelectric layer 112, the upper surface of the lower electrode layer 111 can be maintained in a flat state.

[0072] However, when removing the piezoelectric layer 112 by wet etching within the range of the movable part 40, as Figure 11 shown in (a) of, if the resist 133 is arranged to match the range of the lower electrode layer 111, the lower electrode layer 111 will be peeled off. That is, as Figure 11As shown in (a) of , even if the resist 133 is to be arranged to match the range of the lower electrode layer 111, a gap is generated between the resist 133 and the side surfaces of the lower electrode layer 111 and the piezoelectric layer 112 due to the formation accuracy of the resist pattern. In this case, the etchant (etching solution) for wet etching the piezoelectric layer 112 intrudes from the side surface of the lower electrode layer 111 into the interface between the lower electrode layer 111 and the substrate 101, and dissolves the adhesion layer 121 (buffer layer) formed at the interface. As a result, the lower electrode layer 111 is peeled off from the substrate 101.

[0073] Therefore, in Embodiment 1, as Figure 9 shown, the resist 133 is arranged within the range of the movable part 40 so as to cover the outer peripheral part of the lower electrode layer 111. Thus, as Figure 11 shown in (b) of , no gap is generated between the resist 133 and the side surfaces of the lower electrode layer 111 and the piezoelectric layer 112, and thus peeling of the lower electrode layer 111 caused by the etchant can be suppressed.

[0074] By performing wet etching on the Figure 9 structure, as Figure 12 shown, the piezoelectric layer 112 in the region other than the region where the resist 132 is arranged is removed. Then, as Figure 13 shown, the resist 133 is removed. The middle layer in Figure 13 shows the lower electrode layer 111 ([[]] Figure 2 reflective surface 41 of ) exposed above in the movable part 40, and the lower layer in Figure 13 shows the lower electrode layer 111 ([[]] Figure 1 third electrode part 73 of ) exposed above.

[0075] Next, as Figure 14 shown, a resist 134 is arranged in the region where the substrate 101 remains. Specifically, the region where the substrate 101 remains is the range of the entire structure shown in the Figure 1 top view of . Then, dry etching is performed on the Figure 14 structure from above. Thus, as Figure 15 shown, the substrate 101 in the region other than the resist 134 is removed, and then the resist 134 is removed. The optical reflection element 1 is completed in this way.

[0076] Figure 16 is a flowchart showing the formation process of the optical reflection element 1.

[0077] A thermal oxide film is formed in advance on the upper surface of the substrate 101 by thermal oxidation treatment. Then, as Figure 3As shown, for the substrate 101, the bonding layer 121, the lower electrode layer 111, the piezoelectric layer 112, the bonding layer 122, and the upper electrode layer 113 are sequentially laminated from the substrate 101 side by sputtering to form the pre-process substrate 100 (S1).

[0078] Next, as Figure 4 , Figure 5 shown, for the pre-process substrate 100 formed in step S1, the upper electrode layer 113 outside the ranges of these components is removed by dry etching in such a manner that the upper electrode layer 113 remains within the ranges of the drive unit 50, the detection unit 60, the wiring 80, the first electrode unit 71, and the second electrode unit 72 (S2). Next, as Figures 6 to 8 shown, the lower electrode layer 111 and the piezoelectric layer 112 outside the ranges of these components are removed by dry etching in such a manner that the lower electrode layer 111 and the piezoelectric layer 112 remain within the ranges of the movable unit 40, the drive unit 50, the detection unit 60, the wiring 80, and the electrode unit 70 (S3).

[0079] Next, as Figure 9 , Figure 12 , Figure 13 shown, the piezoelectric layer 112 is removed from the movable unit 40 and the third electrode unit 73 by wet etching in such a manner that the piezoelectric layer 112 remains on the outer peripheral portion 40a of the movable unit 40 (S4). As a result, the upper surface of the lower electrode layer 111 is exposed in the movable unit 40 and the third electrode unit 73.

[0080] Next, as Figure 14 , Figure 15 shown, the portion of the substrate 101 outside the range of the optical reflection element 1 is removed by dry etching (S5). The optical reflection element 1 is completed in this way.

[0081] <Effects of Embodiment 1>

[0082] According to Embodiment 1, the following effects are exhibited.

[0083] As Figure 2 shown in (a) and (b) thereof, at least a layer structure the same as that in the range from the piezoelectric layer 112 to the upper surface of the substrate 101 within the region of the drive unit 50 is disposed in the region of the outer peripheral portion 40a of the movable unit 40, and a layer structure the same as that in the range from the lower electrode layer 111 to the upper surface of the substrate 101 within the region of the drive unit 50 is disposed in the region of the central portion 40b of the movable unit 40. In the region of the central portion 40b, the upper surface of the lower electrode layer 111 is exposed to the outside to form the reflection surface 41.

[0084] According to this structure, the lower electrode layer 111 is used as the reflective surface 41, so that the reflective surface 41 with a high reflectivity can be simply formed. In addition, in the region of the outer peripheral portion 40a of the movable portion 40, a layer structure similar to the range from the piezoelectric layer 112 to the upper surface of the substrate 101 is arranged and the thickness becomes larger. Therefore, the warping of the reflective surface 41 located inside the layer structure can be suppressed by this layer structure. Here, the layer structure is arranged on the upper surface of the movable portion 40 in the same manner as the reflective surface 41 and is adjacent to the reflective surface 41. Therefore, the warping of the reflective surface 41 can be effectively suppressed by the layer structure. Therefore, the reflective surface 41 with effectively suppressed warping can be stably arranged. Thus, according to the optical reflection element 1 according to the first embodiment, the reflective surface 41 with a high reflectivity and suppressed warping can be simply and stably arranged.

[0085] As Figures 3 to 9 shown, in the manufacturing method of the optical reflection element 1, the lower electrode layer 111, the piezoelectric layer 112, and the upper electrode layer 113 are sequentially formed from the substrate 101 side. The upper electrode layer 113 is removed in such a manner that at least the upper electrode layer 113 remains within the range of the drive portion 50. The lower electrode layer 111 and the piezoelectric layer 112 are removed in such a manner that at least the lower electrode layer 111 and the piezoelectric layer 112 remain within the ranges of the drive portion 50 and the movable portion 40. The piezoelectric layer 112 is removed from the movable portion 40 in such a manner that the piezoelectric layer 112 remains in the outer peripheral portion 40a of the movable portion 40 to expose the upper surface of the lower electrode layer 111. The portion of the substrate 101 other than the optical reflection element 1 is removed.

[0086] According to this method, after forming a layer structure including the lower electrode layer 111, the piezoelectric layer 112, and the upper electrode layer 113 on the substrate 101, these layers of the layer structure are selectively removed by an etching process. Thus, the movable portion 40 and the drive portion 50 can be formed together in the same process. Thereby, device fabrication can be achieved at low cost. In this forming process, by applying wet etching to the region of the central portion 40b of the movable portion 40 to expose the lower electrode layer 111 to the outside, the formation of irregularities caused by etching on the upper surface of the lower electrode layer 111 can be suppressed, and the reduction in the reflectivity of the upper surface can be suppressed. In addition, during this wet etching, since at least the layer structure from the piezoelectric layer 112 to the substrate 101 remains in the region of the outer peripheral portion 40a of the movable portion 40, a resist is arranged on the upper side and the outer side of the outer peripheral portion 40a. Therefore, the etching agent for the wet etching does not invade from the outside the boundary between the substrate 101 and the lower electrode layer 111, and the peeling at the outer peripheral portion of the lower electrode layer 111 can be suppressed. Therefore, the reflective surface 41 with suppressed reduction in reflectivity can be stably arranged in the movable portion 40.

[0087] The piezoelectric layer 112 is made of a single crystal structure. According to this structure, the piezoelectric characteristics can be improved compared with the polycrystalline structure. Therefore, the driving characteristics and driving efficiency of the movable part 40 can be improved.

[0088] In addition, when the piezoelectric layer 112 has a single crystal structure, as Figure 10 shown, if dry etching is applied to the region of the central portion 40b of the movable part 40 to remove the piezoelectric layer 112, it is easy to form irregularities on the upper surface of the lower electrode layer 111 exposed to the outside. On the contrary, if wet etching is applied to the region of the central portion 40b of the movable part 40 to remove the piezoelectric layer 112 as in the first embodiment, it is possible to suppress the formation of irregularities on the upper surface of the lower electrode layer 111, and the lower electrode layer 111 can be exposed to the outside while suppressing the reduction of the reflectance.

[0089] The step of removing the piezoelectric layer 112 from the movable part 40 ( Figure 16 step S4) includes a wet etching step.

[0090] If the piezoelectric layer 112 in the range of the movable part 40 is removed by dry etching, it is easy to form irregularities on the upper surface of the lower electrode layer 111 exposed to the outside. On the contrary, if the piezoelectric layer 112 in the range of the movable part 40 is removed by wet etching as described above, it is possible to suppress the formation of irregularities on the upper surface of the lower electrode layer 111, and the lower electrode layer 111 can be exposed to the outside while suppressing the reduction of the reflectance.

[0091] <First modification of Embodiment 1>

[0092] In the first embodiment, in the movable part 40, only the piezoelectric layer 112 (protrusion 42) is formed on the outer peripheral portion of the lower electrode layer 111, but a monitoring electrode 43 composed of an upper electrode layer 113 may be further formed on the upper portion of the piezoelectric layer 112.

[0093] Figure 17 Figures (a) and (b) respectively show a top view and a cross-sectional view schematically showing the structure of the movable part 40 according to the first modification of Embodiment 1. Figure 17 Figure (b) is a cross-sectional view obtained by observing the cross-section C1 - C2 in the top view of Figure (a) of the first modification of Embodiment 1 along the positive X-axis direction. Figure 17 Figure (a) is a top view of the first modification of Embodiment 1.

[0094] In this first modification, compared with Figure 2Compared with Embodiment 1 shown in (a) and (b), a pair of upper electrode layers 113 remain on the upper surface of the piezoelectric layer 112 (protrusion 42) of the movable part 40. An adhesion layer 122 remains between the piezoelectric layer 112 and the upper electrode layers 113. The pair of upper electrode layers 113 respectively constitute the monitoring electrodes 43. The pair of monitoring electrodes 43 are symmetrically arranged with respect to the rotation axis R10. A wiring 81 having the same layer structure as the above-mentioned wiring 80 is connected to the monitoring electrode 43. The monitoring electrode 43 (upper electrode layer 113) is connected to the upper electrode layer 113 of other electrode parts arranged in the electrode part 70 via the upper electrode layer 113 of the wiring 81. The other electrode parts are connected to a galvanometer, a current detection circuit, etc. in an external device. The lower electrode layer 111 corresponding to the monitoring electrode 43 is connected to the lower electrode layer 111 of the third electrode part 73 via the lower electrode layer 111 of the wiring 81.

[0095] Figure 18 (a) to (c) of this document illustrate the formation process of the optical reflection element 1 according to Modification Example 1. Here, in the formation process of the movable part 40, for convenience, only the formation process different from Embodiment 1 will be described.

[0096] Figure 18 (a) of this document is a cross-sectional view corresponding to the middle layer diagram of Modification Example 1 related to Figure 5 In Modification Example 1, a resist 131 is disposed in the region where the upper electrode layer 113 remains. As shown in Figure 18 (a) of this document, the upper electrode layer 113 in the region other than the resist 131 is removed by dry etching.

[0097] Figure 18 (b) of this document is a cross-sectional view corresponding to the middle layer diagram of Modification Example 1 related to Figure 9 In Modification Example 1, a resist 133 is also disposed in the region other than the region where the piezoelectric layer 112 is to be removed. At this time, the diameter d3 of the region where the piezoelectric layer 112 is to be removed is smaller than the inner diameter d1 of the upper electrode layer 113, and the range of the diameter d3 is located inside the range of the diameter d1. That is, the resist 133 is disposed so as to cover the upper electrode layer 113 in the movable part 40. Then, Figure 18 the structure of (b) of this document is wet-etched from above.

[0098] Figure 18 (c) of this document is a cross-sectional view corresponding to the middle layer diagram of Modification Example 1 related to Figure 12The cross-sectional view corresponding to the middle layer diagram. In the first modification example, the lower electrode layer 111 is also exposed upward by removing the piezoelectric layer 112 in the range of the diameter d3. At this time, the inner diameter d3 of the piezoelectric layer 112 is smaller than the inner diameter d1 of the upper electrode layer 113. Then, in the same manner as in the first embodiment, the resist 133 and the unnecessary substrate 101 are removed to complete the optical reflection element 1.

[0099] <Effects of the First Modification Example of the First Embodiment>

[0100] Compared with the structure of the first embodiment, in the region of the outer peripheral portion 40a of the movable portion 40, the layer structure from the upper electrode layer 113 to the upper surface of the piezoelectric layer 112 is also arranged in the region where the driving portion 50 is arranged.

[0101] When the movable portion 40 rotates, the movable portion 40 itself deforms and deflects due to the inertial force generated in the movable portion 40, and the amount of deformation can be detected by the piezoelectric effect of the piezoelectric layer 112 arranged in the outer peripheral portion 40a. According to the above structure, an electric signal corresponding to the deflection and deflection angle of the piezoelectric layer 112 (protrusion 42) arranged in the region of the outer peripheral portion 40a of the movable portion 40 can be obtained via the lower electrode layer 111 and the upper electrode layer 113 arranged in the region of the outer peripheral portion 40a of the movable portion 40. Therefore, the deflection and deflection angle of the movable portion 40 when driving the movable portion 40 can be detected based on this electric signal.

[0102] Specifically, the deflection and deflection angle of the movable portion 40 on the negative Y-axis side of the rotation axis R10 can be detected based on the current detected by the monitoring electrode 43 on the negative Y-axis side of the rotation axis R10, and the deflection and deflection angle of the movable portion 40 on the positive Y-axis side of the rotation axis R10 can be detected based on the current detected by the monitoring electrode 43 on the positive Y-axis side of the rotation axis R10.

[0103] In addition, in the above structure, the other electrode portions of the electrode portion 70 connected to the upper electrode layer 113 (monitoring electrode 43) are connected to a galvanometer, a current detection circuit, etc. in an external device, but it is not limited thereto, and it may also be connected to a power supply, a power supply circuit, etc. in an external device. In this case, the upper electrode layer 113 of the movable portion 40 constitutes a correction electrode. According to this structure, by applying a voltage to the piezoelectric layer 112 via the lower electrode layer 111 and the upper electrode layer 113 arranged in the region of the outer peripheral portion 40a of the movable portion 40, the piezoelectric layer 112 can be expanded and contracted by the inverse piezoelectric effect. Therefore, the deflection of the movable portion 40 when driving the movable portion 40 can be corrected by this expansion and contraction.

[0104] Specifically, by applying a voltage to the piezoelectric layer 112 corresponding to the correction electrode on the negative side of the Y-axis, the deflection of the movable portion 40 on the negative side of the Y-axis of the rotation axis R10 can be corrected. By applying a voltage to the piezoelectric layer 112 corresponding to the correction electrode on the positive side of the Y-axis, the deflection of the movable portion 40 on the positive side of the Y-axis of the rotation axis R10 can be corrected.

[0105] The upper electrode layer 113 within the region of the outer peripheral portion 40a of the movable portion 40 is provided symmetrically with respect to the rotation axis R10.

[0106] According to this structure, it is possible to smoothly detect the deflection and deflection angle of the movable portion 40 from the neutral state with respect to the rotation axis R10. In addition, when the upper electrode layer 113 of the movable portion 40 constitutes the above-described correction electrode, it is possible to smoothly correct the deflection of the movable portion 40 from the neutral state with respect to the rotation axis R10.

[0107] As Figure 18 shown in (a) of [], in the process of removing the upper electrode layer 113, the upper electrode layer 113 also remains in the outer peripheral portion 40a of the movable portion 40. As Figure 18 shown in (b) and (c) of [], in the process of removing the piezoelectric layer 112 from the movable portion 40, the piezoelectric layer 112 is removed in such a manner that the upper electrode layer 113 and the piezoelectric layer 112 remain in the outer peripheral portion 40a of the movable portion 40.

[0108] According to this process, it is possible to obtain an electrical signal corresponding to the deflection and deflection angle of the piezoelectric layer 112 of the movable portion 40 through the lower electrode layer 111 and the upper electrode layer 113 (monitoring electrode 43) of the movable portion 40. Therefore, it is possible to detect the deflection and deflection angle of the movable portion 40 when driving the movable portion 40 based on this electrical signal. In addition, when the upper electrode layer 113 of the movable portion 40 constitutes the above-described correction electrode, by applying a voltage to the piezoelectric layer 112 via the lower electrode layer 111 and the upper electrode layer 113 (correction electrode) of the movable portion 40, the piezoelectric layer 112 of the movable portion 40 can be expanded and contracted. Therefore, it is possible to correct the deflection of the movable portion 40 when driving the movable portion 40 through this expansion and contraction.

[0109] In addition, as Figure 18 shown in (b) of [], by disposing the resist 133 so as to cover the upper electrode layer 113, it is possible to prevent the adhesion layer 122 from being dissolved by the etchant for wet etching of the piezoelectric layer 112. Thereby, it is possible to prevent the upper electrode layer 113 from peeling off from the piezoelectric layer 112.

[0110] <Modification Example 2 of Embodiment 1>

[0111] In Modification Example 1 of Embodiment 1, the monitoring electrode 43 is formed on the upper portion of the piezoelectric layer 112, but the correction electrode 44 may also be further disposed.

[0112] Figure 19 Figures (a) and (b) schematically show a plan view and a cross-sectional view of the movable part 40 according to Modification 2 of Embodiment 1.

[0113] In this Modification 2, compared with Modification 1 shown in Figures (a) and (b), Figure 17 three pairs of upper electrode layers 113 remain on the upper surface of the piezoelectric layer 112 (protrusion 42) of the movable part 40.

[0114] Two pairs of upper electrode layers 113 located at positions far from the C1-C2 cross-section constitute monitoring electrodes 43. One pair of upper electrode layers 113 located at a position intersecting the C1-C2 cross-section constitutes a calibration electrode 44. The two pairs of monitoring electrodes 43 and one pair of calibration electrodes 44 are symmetrically arranged with respect to the rotation axis R10.

[0115] The monitoring electrodes 43 and the calibration electrode 44 have the same layer structure as the monitoring electrodes 43 in Modification 1 above. The wirings 81 to 83 have the same layer structure as the wiring 81 in Modification 1 above.

[0116] Two monitoring electrodes 43 (upper electrode layers 113) located on the positive X-axis side of the C1-C2 cross-section and one calibration electrode 44 (upper electrode layer 113) located on the negative Y-axis side are respectively connected to upper electrode layers 113 of other different electrode parts of the electrode part 70 provided on the positive X-axis side via the wirings 81, 82, and 83. The corresponding lower electrode layers 111 of these two monitoring electrodes 43 and one calibration electrode 44 are respectively connected to the lower electrode layer 111 of the third electrode part 73 of the electrode part 70 provided on the positive X-axis side via the lower electrode layers 111 of the wirings 81, 82, and 83.

[0117] Two monitoring electrodes 43 (upper electrode layers 113) located on the negative X-axis side of the C1-C2 cross-section and one calibration electrode 44 (upper electrode layer 113) located on the positive Y-axis side are respectively connected to upper electrode layers 113 of other different electrode parts of the electrode part 70 provided on the negative X-axis side via the wirings 81, 82, and 83. The corresponding lower electrode layers 111 of these two monitoring electrodes 43 and one calibration electrode 44 are respectively connected to the lower electrode layer 111 of the third electrode part 73 of the electrode part 70 provided on the negative X-axis side via the lower electrode layers 111 of the wirings 81, 82, and 83.

[0118] The above-mentioned other electrode parts to which the four monitoring electrodes 43 are connected are respectively connected to a galvanometer, a current detection circuit, etc. in an external device. The above-mentioned other electrode parts to which the two calibration electrodes 44 are connected are respectively connected to a power supply, a power supply circuit, etc. in an external device.

[0119] <Effect of Modification Example 2 of Embodiment 1>

[0120] Two pairs of monitoring electrodes 43 formed by the upper electrode layer 113 and a pair of calibration electrodes 44 are arranged in the region of the outer peripheral portion 40a of the movable portion 40.

[0121] According to this structure, an electrical signal corresponding to the deflection and deflection angle of the piezoelectric layer 112 (protrusion 42) arranged in the region of the outer peripheral portion 40a can be obtained by the lower electrode layer 111 and the upper electrode layer 113 (monitoring electrode 43) arranged in the region of the outer peripheral portion 40a of the movable portion 40. Therefore, the deflection and deflection angle of the movable portion 40 when driving the movable portion 40 can be detected based on this electrical signal. In addition, by applying a voltage to the piezoelectric layer 112 via the lower electrode layer 111 and the upper electrode layer 113 (calibration electrode 44) arranged in the region of the outer peripheral portion 40a of the movable portion 40, the piezoelectric layer 112 can be expanded and contracted. Therefore, the deflection of the movable portion 40 when driving the movable portion 40 can be corrected by this expansion and contraction.

[0122] Specifically, the deflection and deflection angle of the movable portion 40 on the negative Y-axis side of the rotation axis R10 can be detected based on the current detected by the two monitoring electrodes 43 on the negative Y-axis side of the rotation axis R10, and the deflection and deflection angle of the movable portion 40 on the positive Y-axis side of the rotation axis R10 can be detected based on the current detected by the two monitoring electrodes 43 on the positive Y-axis side of the rotation axis R10. In addition, by applying a voltage to the piezoelectric layer 112 corresponding to the calibration electrode 44 on the negative Y-axis side, the deflection of the movable portion 40 on the negative Y-axis side of the rotation axis R10 can be corrected, and by applying a voltage to the piezoelectric layer 112 corresponding to the calibration electrode 44 on the positive Y-axis side, the deflection of the movable portion 40 on the positive Y-axis side of the rotation axis R10 can be corrected.

[0123] In addition, in Modification Example 2, the upper electrode layer 113 constituting the monitoring electrode 43 can also be used as a calibration electrode, and the upper electrode layer 113 constituting the calibration electrode 44 can also be used as a monitoring electrode.

[0124] The upper electrode layer 113 of the movable portion 40 is symmetrically arranged with respect to the rotation axis R10.

[0125] According to this structure, the deflection and deflection angle of the movable portion 40 from the neutral state with respect to the rotation axis R10 can be smoothly detected, and the deflection of the movable portion 40 from the neutral state with respect to the rotation axis R10 can be smoothly corrected.

[0126] <Modification Example 3 of Embodiment 1>

[0127] In Embodiment 1, the protrusion 42 is formed in a ring shape, but the shape of the protrusion 42 is not limited to a ring shape. For example, a protrusion 42a may be formed on the inner side surface of the ring-shaped portion of the protrusion 42.

[0128] Figure 20 (a) and (b) thereof are a top view and a cross-sectional view schematically showing the structure of the movable portion 40 according to Modification 3 of Embodiment 1.

[0129] In this Modification 3, compared with Embodiment 1 shown in (a) and (b) of Figure 2 by causing a part of the inner side surface of the protrusion 42 (piezoelectric layer 112) of the movable portion 40 to protrude inward, the protrusion 42a is formed. In the examples of (a) and (b) of Figure 20 two protrusions 42a are formed at positions overlapping the rotation axis R10, and two protrusions 42a are formed at positions overlapping the cross-section of C1 - C2. An air retention portion 45 for retaining air is formed in the region surrounded by the inner side surface of the protrusion 42 and the sides of the plurality of protrusions 42a. In Figure 20 (a) thereof, for convenience, the region corresponding to the air retention portion 45 is shaded.

[0130] <Effect of Modification 3 of Embodiment 1>

[0131] By causing the protrusion 42 (piezoelectric layer 112) disposed on the outer peripheral portion 40a of the movable portion 40 to protrude toward the central portion 40b, an air retention portion 45 for retaining air is formed.

[0132] According to this structure, in the movable portion 40, even if there is dust near the upper surface of the lower electrode layer 111 constituting the reflecting surface 41, the dust will be retained in the air retention portion 45. Thereby, a decrease in the reflectance of the reflecting surface 41 can be suppressed.

[0133] <Embodiment 2>

[0134] In Embodiment 1, the vibrating portions 21 and 22 are arranged in a tuning fork shape, but in Embodiment 2, the vibrating portion is arranged in a meander shape.

[0135] Figure 21 is a top view schematically showing the structure of the optical reflection element 2 according to Embodiment 2.

[0136] The optical reflection element 2 includes a fixing portion 10, a pair of vibrating portions 221 to 224, a pair of connecting portions 231 to 235, movable portions 40, eight driving portions 50, ten wirings 80, and a pair of electrode portions 270. The optical reflection element 2 is configured to be symmetric about the center C10 point. Hereinafter, for convenience, the same reference numerals as those in the first embodiment are given to the same structures.

[0137] In a plan view, the pair of vibrating portions 221 to 224 and the pair of connecting portions 231 to 235 are arranged between the inner part of the frame shape of the fixing portion 10 and the movable portion 40. Groups formed by the vibrating portions 221 to 224 and the connecting portions 231 to 235 are respectively arranged on the positive X-axis side and the negative X-axis side of the movable portion 40. In a plan view, the vibrating portions 221 to 224 located on the positive X-axis side or the negative X-axis side of the movable portion 40 are in a meandering shape.

[0138] The vibrating portions 221 to 224 have a rectangular shape that is longer in the Y-axis direction than in the X-axis direction. The vibrating portion 221 on the negative X-axis side of the movable portion 40 is connected to the fixing portion 10 through the connecting portion 231 at the end on the negative Y-axis side. The vibrating portion 222 on the negative X-axis side of the movable portion 40 is connected to the vibrating portion 221 through the connecting portion 232 at the end on the positive Y-axis side. The vibrating portion 223 on the negative X-axis side of the movable portion 40 is connected to the vibrating portion 222 through the connecting portion 233 at the end on the negative Y-axis side. The vibrating portion 224 on the negative X-axis side of the movable portion 40 is connected to the vibrating portion 223 through the connecting portion 234 at the end on the positive Y-axis side. The vibrating portion 224 on the negative X-axis side of the movable portion 40 is connected to the movable portion 40 through the connecting portion 235 at the end on the negative Y-axis side. The vibrating portions 221 to 224 and the connecting portions 231 to 235 on the positive X-axis side of the movable portion 40 have a point-symmetric structure with respect to the center C10 with the vibrating portions 221 to 224 and the connecting portions 231 to 235 on the negative X-axis side of the movable portion 40.

[0139] Four drive units 50 are disposed on the upper surfaces of the vibration units 221 to 224 on the negative X-axis side of the movable unit 40, and four drive units 50 are disposed on the upper surfaces of the vibration units 221 to 224 on the positive X-axis side of the movable unit 40. The drive unit 50 is connected to the first electrode unit 271 or the second electrode unit 272 of the electrode unit 270 via the wiring 80. The layer structures of the drive unit 50 and the wiring 80 are the same as those in the first embodiment. The layer structures of the electrode unit 270, the first electrode unit 271, the second electrode unit 272, and the third electrode unit 273 are the same as those of the electrode unit 70, the first electrode unit 71, the second electrode unit 72, and the third electrode unit 73 in the first embodiment. On the upper surfaces of the first electrode unit 271, the second electrode unit 272, and the third electrode unit 273, cables (external wirings) connected to an external device are respectively connected by wire bonding. The first electrode unit 271 and the second electrode unit 272 are connected to a power supply, a power supply circuit, etc. in the external device. The third electrode unit 273 is connected to a ground wire in the external device.

[0140] When a drive voltage is applied to the drive units 50 on the vibration units 221 and 223 connected to the first electrode unit 271 via the first electrode unit 271, the piezoelectric layer 112 in the drive unit 50 deforms, and the vibration units 221 and 223 perform flexural vibration. On the other hand, when a drive voltage is applied to the drive units 50 on the vibration units 222 and 224 connected to the second electrode unit 272 via the second electrode unit 272, the piezoelectric layer 112 in the drive unit 50 deforms, and the vibration units 222 and 224 perform flexural deformation. Thus, due to the deformation of the vibration units 221 to 224, the movable unit 40 rotates about the rotation axis R10.

[0141] In addition, either the first electrode unit 271 or the second electrode unit 272 may also be connected to a galvanometer, a current detection circuit, etc. in the external device. In this case, the drive unit 50 connected to one of the first electrode unit 271 and the second electrode unit 272 that is connected to the galvanometer or the like constitutes a detection unit, and the flexure of the vibration unit provided with the detection unit can be detected based on the detected current value.

[0142] In the second embodiment, the movable unit 40 is also configured in the same manner as in the first embodiment, and thus exhibits the same effects as those in the first embodiment. In addition, in the second embodiment, the movable unit 40 may also be configured in the same manner as in the first modification examples 1 to 3 of the first embodiment. In this case, the same effects as those in the first modification examples 1 to 3 of the first embodiment are also exhibited.

[0143] <Other Modification Examples>

[0144] In the above-described embodiments and modified examples, the piezoelectric layer 112 is formed of a single crystal structure of PZT. However, it is not limited thereto, and it may be formed of a polycrystalline structure of PZT. When the piezoelectric layer 112 formed of polycrystalline PZT is removed by dry etching, the degree of unevenness generated on the upper surface of the lower electrode layer 111 is lower than that in the case where the piezoelectric layer 112 formed of single crystal PZT is removed by dry etching. However, unevenness may still be formed on the upper surface of the lower electrode layer 111. Therefore, when the piezoelectric layer 112 is formed of a polycrystalline structure of PZT, it is also preferable to remove the piezoelectric layer 112 in the range of the movable portion 40 by wet etching, as in the above-described embodiments and modified examples.

[0145] In the above-described embodiments and modified examples, the piezoelectric layer 112 is formed of PZT, but it may also be formed of other materials having a piezoelectric effect. In this case, the other materials having a piezoelectric effect are also preferably formed of a single crystal structure. Thereby, the driving characteristics and driving efficiency of the movable portion 40 can be improved. In addition, when the other materials having a piezoelectric effect are formed of a single crystal structure, it is preferable to remove the piezoelectric layer 112 in the range of the movable portion 40 by wet etching. Thereby, the formation of unevenness on the upper surface of the lower electrode layer 111 can be suppressed.

[0146] In the above-described embodiments and modified examples, the outer peripheral portion 40a of the movable portion 40 is located inside the outer edge of the substrate 101. However, it is not limited thereto, and it may be positioned along the outer edge of the substrate 101. That is, in the movable portion 40, the outer edges of the lower electrode layer 111 and the piezoelectric layer 112 may also coincide with the outer edge of the substrate 101.

[0147] In the above-described embodiments and modified examples, the piezoelectric layer 112 of the movable portion 40 is disposed over the entire circumference of the outer peripheral portion 40a, but it may also be disposed on a part of the outer peripheral portion 40a. In this case, it is also possible to suppress peeling of the lower electrode layer 111 due to the etching agent of wet etching at the position of the outer peripheral portion 40a where the piezoelectric layer 112 is disposed. However, as in the above-described embodiments and modified examples, disposing the piezoelectric layer 112 over the entire circumference of the outer peripheral portion 40a can more reliably suppress peeling of the lower electrode layer 111 due to the etching agent of wet etching.

[0148] In the above-described embodiments and modified examples, the lower electrode layer 111 is formed of platinum (Pt), but it may also be formed of other conductive materials. The upper electrode layer 113 is formed of gold (Au), but it may also be formed of other conductive materials. The adhesion layers 121 and 122 are formed of titanium (Ti), but they may also be formed of Cr (chromium) or W (tungsten).

[0149] In the above-described Embodiments 1 and 2, as Figure 1 , Figure 21As shown, two drive units are arranged with the movable part 40 sandwiched therebetween, but either one of the two drive units may be omitted. For example, in Figure 1 in the first embodiment shown, the structure on the positive X-axis side of the movable part 40 may also be omitted, and the movable part 40 is supported by the connecting part 31 on the negative X-axis side. In Figure 21 in the second embodiment shown, the structure on the positive X-axis side of the movable part 40 may also be omitted, and the movable part 40 is supported by the connecting part 235 on the negative X-axis side.

[0150] In addition, in the above-described first and second embodiments, the annular protrusion 42 (piezoelectric layer 112) is arranged over the entire range of the region of the outer peripheral part 40a of the movable part 40. However, as long as warping of the reflecting surface 41 can be suppressed, a part of the protrusion 42 (piezoelectric layer 112) may be missing.

[0151] Furthermore, from the viewpoint of suppressing peeling at the outer peripheral part of the lower electrode layer 111 and stably arranging the reflecting surface 41, after the optical reflecting elements 1 and 2 are formed by Figures 3 to 9 the manufacturing method, the protrusion 42 (piezoelectric layer 112) may be entirely removed. For the piezoelectric layer formed in the region of the outer peripheral part of the movable part by the manufacturing method of the present invention, no matter what kind of processing is performed thereafter, as long as all of the manufacturing method of the present invention is implemented, its manufacturing process can be included in the technical scope of the manufacturing method of the present invention.

[0152] In addition, in the above-described first and second embodiments, warping of the reflecting surface 40 is suppressed by arranging the protrusion 42 (piezoelectric layer 112) in the region of the outer peripheral part 40a of the movable part 40. However, the present invention does not exclude at all the case where a structure for suppressing warping of the reflecting surface 40 is arranged in a region other than the outer peripheral part 40a of the movable part 40. When the thickness of the piezoelectric layer 112 is small and the height of the protrusion 42 is low, for example, ribs for suppressing warping of the reflecting surface 40 may be further arranged on the lower surface of the movable part 40, thereby improving the effect of suppressing warping of the reflecting surface 40. In addition, as described above, in the case where the protrusion 42 (piezoelectric layer 112) is entirely removed after the optical reflecting elements 1 and 2 are formed by Figures 3 to 9 the manufacturing method, ribs for suppressing warping of the reflecting surface 40 may be arranged on the lower surface of the movable part 40.

[0153] In addition, the embodiments of the present invention can be appropriately modified within the scope of the technical idea shown in the claims.

[0154] (Supplementary Note)

[0155] Based on the description of the above embodiments, the following technology is disclosed.

[0156] (Technology 1)

[0157] An optical reflection element, characterized in that it comprises:

[0158] A movable part; and

[0159] A driving part that rotates the movable part around a rotation axis,

[0160] wherein, in the area of the driving part on the substrate forming the contour of the optical reflection element, there are arranged:

[0161] A lower electrode layer;

[0162] An upper electrode layer, which is located on the upper side of the lower electrode layer; and

[0163] A piezoelectric layer, which is located between the lower electrode layer and the upper electrode layer,

[0164] In the area of the outer peripheral part of the movable part on the substrate, there is at least arranged a layer structure the same as the range from the piezoelectric layer to the upper surface of the substrate in the area of the driving part,

[0165] In the area of the central part of the movable part on the substrate, there is arranged a layer structure the same as the range from the lower electrode layer to the upper surface of the substrate in the area of the driving part,

[0166] In the area of the central part, the upper surface of the lower electrode layer is exposed to the outside and constitutes a reflection surface.

[0167] According to this technique, since the lower electrode layer is used as the reflection surface, a reflection surface with a high reflectivity can be simply formed. In addition, in the area of the outer peripheral part of the movable part, a layer structure the same as the range from the piezoelectric layer to the upper surface of the substrate is arranged and the thickness becomes larger, so the warping of the reflection surface located inside the layer structure can be suppressed by this layer structure. Here, the layer structure is arranged on the upper surface of the movable part in the same way as the reflection surface and is adjacent to the reflection surface, so the warping of the reflection surface can be effectively suppressed by the layer structure. Therefore, a reflection surface with effectively suppressed warping can be stably arranged. Thus, according to the optical reflection element according to this embodiment, a high-reflectivity reflection surface with suppressed warping can be simply and stably arranged.

[0168] (Technique 2)

[0169] The optical reflection element according to Technique 1, characterized in that

[0170] In the area of the outer peripheral part of the movable part, there is also arranged a layer structure from the upper electrode layer to the upper surface of the piezoelectric layer in the area of the driving part.

[0171] According to this technology, an electric signal corresponding to the flexure and deflection angle of the piezoelectric layer disposed in the region of the outer peripheral portion of the movable portion can be obtained via the lower electrode layer and the upper electrode layer disposed in the region of the outer peripheral portion. Therefore, the flexure and deflection angle of the movable portion during driving of the movable portion can be detected based on this electric signal. Further, by applying a voltage to the piezoelectric layer via the lower electrode layer and the upper electrode layer disposed in the region of the outer peripheral portion of the movable portion, the piezoelectric layer can be expanded and contracted. Therefore, the flexure of the movable portion during driving of the movable portion can be corrected by this expansion and contraction.

[0172] (Technology 3)

[0173] The optical reflection element according to Technology 2, wherein

[0174] the upper electrode layer in the region of the outer peripheral portion of the movable portion is symmetrically disposed about the rotation axis.

[0175] According to this technology, the flexure and deflection angle of the movable portion from the neutral state with respect to the rotation axis can be smoothly detected, and the flexure of the movable portion from the neutral state with respect to the rotation axis can be smoothly corrected.

[0176] (Technology 4)

[0177] The optical reflection element according to any one of Technologies 1 to 3, wherein

[0178] By causing the piezoelectric layer disposed in the outer peripheral portion of the movable portion to protrude toward the central portion, an air retention portion for retaining air is formed.

[0179] According to this technology, in the movable portion, even if dust exists near the upper surface of the second electrode layer constituting the reflection surface, the dust stays in the air retention portion. Thereby, a decrease in the reflectance of the reflection surface can be suppressed.

[0180] (Technology 5)

[0181] The optical reflection element according to any one of Technologies 1 to 4, wherein

[0182] the piezoelectric layer is composed of a single crystal structure.

[0183] According to this technology, piezoelectric characteristics can be improved as compared with a polycrystalline structure. Therefore, the driving characteristics and driving efficiency of the movable portion can be improved.

[0184] (Technology 6)

[0185] A method for manufacturing an optical reflection element, wherein

[0186] a lower electrode layer, a piezoelectric layer, and an upper electrode layer are sequentially formed from the substrate side,

[0187] Remove the upper electrode layer in such a way that the upper electrode layer remains at least within the range of the drive unit.

[0188] Remove the lower electrode layer and the piezoelectric layer in such a way that the lower electrode layer and the piezoelectric layer remain at least within the range of the drive unit and the movable unit.

[0189] Remove the piezoelectric layer from the movable unit in such a way that the piezoelectric layer remains at the outer peripheral portion of the movable unit, exposing the upper surface of the lower electrode layer.

[0190] Remove the portion of the substrate outside the range of this optical reflection element.

[0191] According to this technique, after forming a layer structure including a lower electrode layer, a piezoelectric layer, and an upper electrode layer on a substrate, these layers of the layer structure are selectively removed by an etching process. Thus, the movable unit and the drive unit can be formed together in the same process. As a result, device fabrication can be achieved at low cost. In this forming process, wet etching is applied to the region of the central portion of the movable unit to expose the lower electrode layer to the outside. Thus, it is possible to suppress the formation of irregularities caused by etching on the upper surface of the lower electrode layer and suppress the reduction in the reflectance of this upper surface. In addition, during this wet etching, at least the layer structure from the piezoelectric layer to the substrate remains in the region of the outer peripheral portion of the movable unit. Therefore, a resist is disposed on the upper side and the outside of this outer peripheral portion. Therefore, the etching agent for the wet etching does not invade from the outside the boundary between the substrate and the lower electrode layer, and it is possible to suppress peeling at the outer peripheral portion of the lower electrode layer. Therefore, it is possible to simply and stably dispose a reflecting surface with reduced reflectance reduction on the movable unit.

[0192] (Technique 7)

[0193] The manufacturing method of the optical reflection element according to Technique 6, characterized in that

[0194] In the process of removing the upper electrode layer, the upper electrode layer also remains at the outer peripheral portion of the movable unit.

[0195] In the process of removing the piezoelectric layer from the movable unit, the piezoelectric layer is removed in such a way that the upper electrode layer and the piezoelectric layer remain at the outer peripheral portion of the movable unit.

[0196] According to this technology, an electrical signal corresponding to the flexure and deflection angle of the piezoelectric layer of the movable part can be obtained through the lower electrode layer and the upper electrode layer of the movable part. Therefore, the flexure and deflection angle of the movable part during driving can be detected based on this electrical signal. In addition, by applying a voltage to the piezoelectric layer via the lower electrode layer and the upper electrode layer of the movable part, the piezoelectric layer of the movable part can be expanded and contracted. Therefore, the flexure of the movable part during driving can be corrected by this expansion and contraction.

[0197] (Technology 8)

[0198] The manufacturing method of the optical reflection element according to Technology 6 or 7 is characterized in that

[0199] The process of removing the piezoelectric layer from the movable part includes a wet etching process.

[0200] If the piezoelectric layer in the range of the movable part is removed by dry etching, it is easy to form irregularities on the upper surface of the lower electrode layer exposed to the outside. In contrast, according to the above technology, if the piezoelectric layer in the range of the movable part is removed by wet etching, the formation of irregularities on the lower electrode layer can be suppressed, and the lower electrode layer can be exposed to the outside while suppressing the reduction of reflectivity.

[0201] Description of reference numerals

[0202] 1, 2: Optical reflection element; 40: Movable part; 40a: Outer peripheral part; 40b: Central part; 41: Reflecting surface; 45: Air retention part; 50: Driving part; 101: Substrate; 111: Lower electrode layer; 112: Piezoelectric layer; 113: Upper electrode layer; R10: Rotation axis.

Claims

1. An optical reflection element, characterized in that, Comprising: A movable part; and A driving part that rotates the movable part around a rotation axis, wherein, in the region of the driving part on the substrate forming the contour of the optical reflection element, there are disposed: A lower electrode layer; An upper electrode layer located on the upper side of the lower electrode layer; and A piezoelectric layer located between the lower electrode layer and the upper electrode layer, In the region of the outer peripheral part of the movable part on the substrate, at least the same layer structure as the range from the piezoelectric layer to the upper surface of the substrate in the region of the driving part is disposed. In the region of the central part of the movable part on the substrate, the same layer structure as the range from the lower electrode layer to the upper surface of the substrate in the region of the driving part is disposed. In the region of the central part, the upper surface of the lower electrode layer is exposed to the outside to form a reflection surface.

2. The optical reflection element according to claim 1, wherein In the region of the outer peripheral part of the movable part, the layer structure from the upper electrode layer to the upper surface of the piezoelectric layer in the region of the driving part is further disposed.

3. The optical reflection element according to claim 2, wherein The upper electrode layer in the region of the outer peripheral part of the movable part is symmetrically arranged with respect to the rotation axis.

4. The optical reflection element according to any one of claims 1 to 3, wherein By making the piezoelectric layer disposed in the outer peripheral part of the movable part protrude toward the central part, an air retention part for retaining air is formed.

5. The optical reflection element according to claim 1, wherein The piezoelectric layer is composed of a single crystal structure.

6. A manufacturing method of an optical reflection element, characterized in that The lower electrode layer, the piezoelectric layer, and the upper electrode layer are sequentially formed from the substrate side, The upper electrode layer is removed in such a manner that at least the upper electrode layer remains within the range of the driving part, The lower electrode layer and the piezoelectric layer are removed in such a manner that at least the lower electrode layer and the piezoelectric layer remain within the ranges of the driving part and the movable part, The piezoelectric layer is removed from the movable part in such a manner that the piezoelectric layer remains in the outer peripheral part of the movable part, and the upper surface of the lower electrode layer is exposed, The part of the substrate other than the range of this optical reflection element is removed.

7. The manufacturing method of the optical reflection element according to claim 6, wherein In the process of removing the upper electrode layer, the upper electrode layer also remains in the outer peripheral part of the movable part, In the process of removing the piezoelectric layer from the movable part, the piezoelectric layer is removed in such a manner that the upper electrode layer and the piezoelectric layer remain in the outer peripheral part of the movable part.

8. The manufacturing method of the optical reflection element according to claim 6 or 7, wherein The process of removing the piezoelectric layer from the movable part includes a wet etching process.

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