Drive element

Abstract

This drive element (1) comprises a fixed part, a drive unit that is aligned on the side of the fixed part and that is linked to the fixed part, and a moveable part that is driven by the drive unit. A lower electrode (111), a piezoelectric layer (112), and an upper electrode (114) are formed in order on an upper surface region of the fixed part and the drive unit. Furthermore, in a wiring region (A1) on the fixed-part side of the upper surface region, a low dielectric layer (115) including at least one element that forms the piezoelectric layer (112) is formed on the upper surface of the piezoelectric layer (112).

Description

Drive element

[0001] The present invention relates to a driving element in which a piezoelectric layer is arranged.

[0002] In recent years, various devices have been developed using driving elements with piezoelectric layers. Patent Document 1 below describes an inertial force sensor that includes a base, a lower electrode layer formed on the top surface of the base, a piezoelectric layer formed on the top surface of the lower electrode layer, a capacitance-reducing layer formed on the top surface of the piezoelectric layer, and an upper electrode layer formed on the top surface of the capacitance-reducing layer. The capacitance-reducing layer is made of polyimide.

[0003] Patent No. 5903667

[0004] In the sensor described above, the lower electrode layer, piezoelectric layer, and upper electrode layer are formed to extend into the wiring area for manufacturing purposes. In the above-mentioned Patent Document 1, a capacitance-reducing layer is disposed to suppress noise and unwanted vibrations in this area. However, in the above-mentioned laminated structure in which a capacitance-reducing layer made of polyimide is laminated on the top surface of the piezoelectric layer, the capacitance-reducing layer may peel off from the top surface of the piezoelectric layer.

[0005] In view of the above problem, an object of the present invention is to provide a driving element that can improve the adhesion between a low dielectric layer and a piezoelectric layer.

[0006] A driving element according to a main aspect of the present invention includes a fixed part, a driving part connected to the side of the fixed part, and a movable part driven by the driving part. A lower electrode, a piezoelectric layer, and an upper electrode are formed in this order on upper surface regions of the fixed part and the driving part, and further, in a wiring region on the fixed part side of the upper surface region, a low-dielectric layer containing at least one element forming the piezoelectric layer is formed on the upper surface of the piezoelectric layer.

[0007] According to the driving element of this embodiment, a low-dielectric layer is formed on the upper surface of the piezoelectric layer in the wiring region, which causes a voltage drop in the wiring region due to the low-dielectric layer, thereby reducing the voltage applied to the piezoelectric layer in the wiring region. This suppresses unnecessary displacement and stress in the wiring region, thereby preventing damage to the driving element (wiring region) and improving reliability. Furthermore, because the low-dielectric layer contains at least one element that forms the piezoelectric layer, interfacial mixing between the low-dielectric layer and the piezoelectric layer is likely to occur, thereby improving adhesion between the low-dielectric layer and the piezoelectric layer. This suppresses peeling of the low-dielectric layer from the upper surface of the piezoelectric layer, thereby improving the reliability of the driving element.

[0008] As described above, according to the present invention, it is possible to provide a driving element that can improve the adhesion between the low dielectric layer and the piezoelectric layer.

[0009] The effects and significance of the present invention will become more apparent from the following description of the embodiments, however, the embodiments shown below are merely examples of how the present invention can be implemented, and the present invention is not limited to the embodiments described below.

[0010] FIG. 1 is a plan view schematically showing the configuration of a driving element according to Embodiment 1. FIG. 2 is a view schematically showing the C1-C2 cross section of FIG. 1 according to Embodiment 1. FIGS. 3(a) and 3(b) are views for explaining the procedure for forming a laminated structure according to Embodiment 1. FIGS. 4(a) and 4(b) are views for explaining the procedure for forming a laminated structure according to Embodiment 1. FIGS. 5(a) and 5(b) are views for explaining the procedure for forming a laminated structure according to Embodiment 1. FIGS. 6(a) and 6(b) are views for explaining the procedure for forming a laminated structure according to Embodiment 2. FIGS. 7(a) and 7(b) are views for explaining the procedure for forming a laminated structure according to Embodiment 3. FIG. 8 is a plan view schematically showing the configuration of a driving element according to Embodiment 4. FIG. 9 is a plan view schematically showing the configuration of a driving element according to Embodiment 5. FIG. 10 is a view schematically showing the C3-C4 cross section of FIG. 9 according to Embodiment 5. Fig. 11 is a block diagram showing the configuration of a drive element and an external device connected to the drive element according to embodiment 5. Fig. 12(a) is a diagram schematically showing the waveform of a reference voltage and the waveform of a detection signal having an amplitude deviation according to embodiment 5. Fig. 12(b) is a diagram schematically showing the waveform of a reference voltage and the waveform of a detection signal having a period deviation according to embodiment 5. Figs. 13(a) and 13(b) are plan views schematically showing the configuration of drive elements according to modifications 1 and 2 of embodiment 5, respectively. Fig. 14 is a plan view schematically showing the configuration of a drive element according to embodiment 6.

[0011] However, the drawings are for illustrative purposes only and do not limit the scope of the present invention.

[0012] Hereinafter, embodiments of the present invention will be described with reference to the drawings. For convenience, each drawing is labeled with mutually orthogonal X, Y, and Z axes. The positive direction of the Z axis is the vertically upward direction.

[0013] First Embodiment FIG. 1 is a plan view schematically showing the configuration of a driving element 1. As shown in FIG.

[0014] The driving element 1 includes a pair of fixed parts 10, a pair of driving parts 20, and a movable part 30. The driving element 1 is configured to be symmetrical in the X-axis direction and the Y-axis direction around the center 30a of the movable part 30. When driven by the driving part 20, the movable part 30 rotates around a rotation axis R10 that passes through the center 30a and extends in the X-axis direction.

[0015] The pair of fixed portions 10 are aligned in the direction of the rotation axis R10. When the driving element 1 is installed, the surface of the fixed portion 10 on the negative side in the Z axis direction (the surface of the base portion 101 on the negative side in the Z axis direction in FIG. 2) is installed at the installation location.

[0016] The pair of drive units 20 are shaped like tuning forks. The pair of drive units 20 are aligned in the direction of the rotation axis R10, lined up beside the pair of fixed units 10, and connected to the fixed units 10, respectively. The drive unit 20 includes a pair of vibration units 21 and connection units 22 and 23. The pair of vibration units 21 are aligned in the Y-axis direction and configured line-symmetrically with respect to the rotation axis R10. The connection units 22 and 23 extend along the rotation axis R10 and are connected to each other. The fixed unit 10 is connected to the outer end of the connection unit 22 (the end facing away from the center 30a), and the movable unit 30 is connected to the inner end of the connection unit 23 (the end facing closer to the center 30a).

[0017] A mirror 31 is provided on the surface on the positive side of the Z axis of the movable part 30. The movable part 30 and the mirror 31 are circular with a center 30a as the center.

[0018] A laminated structure 110 (see FIG. 2 ) is disposed on the upper surface regions of the fixed unit 10 and the drive unit 20. The laminated structure 110 is disposed across the wiring region A1 and the drive region A2. The wiring region A1 is a region including the fixed unit 10, the connection portion 22, and the vicinity of the position where the connection portions 22 and 23 are connected. The drive region A2 is a region of the drive unit 20 located outside the position where the connection portions 22 and 23 are connected in the Y-axis direction with respect to the rotation axis R10. The wiring region A1 is a region for supplying a drive voltage to the drive region A2, and the drive region A2 is a region driven by the supplied drive voltage. The configuration of the laminated structure 110 in the wiring region A1 and the drive region A2 will be described later with reference to FIG. 2 .

[0019] The end of the laminated structure 110 on the fixed unit 10 side in the wiring region A1 is connected to an external power supply or the like. When the driving unit 20 is driven, voltages of opposite phases are applied to the two vibrating units 21 (two laminated structures 110) arranged in the Y-axis direction so that the two vibrating units 21 vibrate in opposite directions in the Z-axis direction. Furthermore, voltages of the same phase are applied to the two vibrating units 21 (two laminated structures 110) arranged in the X-axis direction so that the two vibrating units 21 vibrate in the same direction in the Z-axis direction. As a result, the movable unit 30 and the mirror 31 rotate about the rotation axis R10, and the direction of light incident on the mirror 31 is changed according to the rotation angle of the mirror 31.

[0020] FIG. 2 is a diagram schematically showing a cross section taken along the line C1-C2 of FIG.

[0021] When the C1-C2 cross section is viewed in the Z-axis direction, as shown in FIG. 1, the cross section is bent by 90 degrees near the position where the connecting portions 22 and 23 are connected. In FIG. 2, the stacked structure 110 is illustrated so that these 90-degree bent cross sections (cross sections parallel to the X-Z plane and cross sections parallel to the Y-Z plane) can be viewed on the same plane. In FIGS. 1 and 2, position P1 indicating the boundary between the wiring region A1 and the driving region A2 is illustrated in the C1-C2 cross section. Also illustrated in FIG. 2 are the X, Y, and Z axes indicating the coordinates of the cross section parallel to the X-Z plane of the C1-C2 cross section, and the X, Y, and Z axes indicating the coordinates of the cross section parallel to the Y-Z plane of the C1-C2 cross section.

[0022] In the wiring region A1, a base 101 is disposed in a range corresponding to the fixed portion 10 shown in FIG. 1. On the upper surface of the base 101, a device layer 102 is disposed across the wiring region A1 and the driving region A2. The device layer 102 is disposed in a range corresponding to the fixed portion 10, the driving portion 20, and the movable portion 30 shown in FIG. 1. The base 101 is formed by bonding the BOX layer (SiO ２) and a handle layer (Si). The device layer 102 is composed of the device layer (Si) of the SOI substrate. When forming the base 101 and the device layer 102, the SOI substrate consisting of the device layer, BOX layer, and handle layer is shaped as shown in the plan view of FIG. 1. Thereafter, the BOX layer and the handle layer of the SOI substrate are removed so that only the area of ​​the BOX layer and the handle layer of the SOI substrate corresponding to the fixed portion 10 remains. In this way, the base 101 and the device layer 102 are formed.

[0023] The laminated structure 110 is disposed on the upper surface of the device layer 102. A lower electrode 111, a piezoelectric layer 112, an upper electrode adhesion layer 113, and an upper electrode 114 are formed in this order across the entire laminated structure 110 in the positive direction of the Z axis. In addition, in the wiring region A1 of the laminated structure 110, a low-dielectric layer 115 is formed on the upper surface of the piezoelectric layer 112.

[0024] In the first embodiment, the lower electrode 111 is made of platinum (Pt), and the piezoelectric layer 112 is made of PZT (lead zirconate titanate: Pb(Zr,Ti)O ３ ), the upper electrode adhesive layer 113 is made of nickel (Ni), the upper electrode 114 is made of gold (Au), and the low dielectric layer 115 is made of PbTiO ｘ and titanium dioxide (TiO ２ )

[0025] As shown in FIG. 2, the piezoelectric layer 112 is disposed between the lower electrode 111 and the upper electrode 114 , and therefore also functions as a dielectric that insulates the lower electrode 111 from the upper electrode 114 .

[0026] Furthermore, in the fixed portion 10 (see FIG. 1 ), for example, the lower electrode 111 on the fixed portion 10 side is connected to ground, and a voltage is applied to the upper electrode 114 on the fixed portion 10 side, causing the piezoelectric layer 112 in the drive region A2 to vibrate. This drives the drive unit 20 (see FIG. 1 ), causing the movable portion 30 and the mirror 31 (see FIG. 1 ) to rotate about the rotation axis R10. However, generally, when the piezoelectric layer 112 is disposed in the wiring region A1, unnecessary displacement and stress are generated in the wiring region A1, resulting in damage to the wiring region A1. In contrast, in the first embodiment, the low-dielectric layer 115 is provided in the wiring region A1, thereby suppressing the voltage applied to the wiring region A1. This prevents damage to the wiring region A1 and improves the reliability of the drive element 1.

[0027] Next, with reference to Figures 3(a) to 5(b), a description will be given of a procedure for forming the laminated structure 110. For convenience, the base portion 101 is not shown in Figures 3(a) to 5(b).

[0028] As shown in FIG. 3A, a lower electrode 111 and a piezoelectric layer 112 are formed in this order on the upper surface of the device layer 102 .

[0029] Subsequently, as shown in FIG. 3B, the upper portion of the piezoelectric layer 112 corresponding to the wiring region A1 is removed by etching to a depth corresponding to the low dielectric layer 115 to be formed in the wiring region A1.

[0030] 4A, a metal layer 116 is formed on the entire top surface of the piezoelectric layer 112 shown in FIG. 3B. The metal layer 116 is made of a material that is transformed into a low dielectric layer 115 by heat treatment, which will be described later, and that adheres closely to the piezoelectric layer 112. For example, the metal layer 116 is made of titanium (Ti).

[0031] 4(b), the metal layer 116 in FIG. 4(a) is removed so that it remains only on the top surface of the piezoelectric layer 112 in the wiring region A1. At this time, the metal layer 116 is removed so that the top surface of the metal layer 116 in the wiring region A1 and the top surface of the piezoelectric layer 112 in the drive region A2 are at approximately the same height.

[0032] Next, as shown in FIG. 5A, an upper electrode adhesion layer 113 is formed on the upper surface of the wiring region A1 and the upper surface of the driving region A2 in FIG. 4B. The upper electrode adhesion layer 113 is made of a material that has high adhesion to the upper electrode 114. For example, the upper electrode adhesion layer 113 is made of nickel (Ni). Then, heat is applied to the wiring region A1. As a result, the metal layer 116 is transformed into a low-dielectric layer 115.

[0033] Specifically, a part of titanium constituting the metal layer 116 thermally reacts with the piezoelectric layer 112 to form PbTiO ｘ 5A. Furthermore, other titanium constituting the metal layer 116 bonds with oxygen in the piezoelectric layer 112 and oxygen around the metal layer 116 due to heat, and changes to titanium dioxide. That is, when heat is applied to the metal layer 116, the metal layer 116 changes to a low-dielectric layer 115 containing the components of the piezoelectric layer 112. In other words, the metal layer 116 changes to a low-dielectric layer 115 containing at least one element that forms the piezoelectric layer 112. Furthermore, the closer the metal layer 116 in the state of FIG. 5A is to the piezoelectric layer 112, the more PbTiO ｘ 5B, heat sufficient to cause these reactions is applied to the wiring region A1.

[0034] Here, the metal layer 116 is made of a metal having a lower standard reaction Gibbs energy of oxide than the metal constituting the upper electrode adhesive layer 113. The standard reaction Gibbs energy ΔG of an oxide is expressed as follows: R is the gas constant, T is the absolute temperature, and P is the oxygen partial pressure. Ｏ２ Then, ΔG = -RTlnP Ｏ２ A metal material with a low ΔG oxidizes at a low oxygen partial pressure (low temperature). For example, in a heat treatment atmosphere at 400° C., the metal (titanium) constituting the metal layer 116 oxidizes due to P Ｏ２ is 10 －７ At a pressure of 1 Pa or higher, the metal (nickel) constituting the upper electrode adhesive layer 113 is oxidized to titanium dioxide. Ｏ２ is 10 －１ At temperatures above 1 Pa, the material is oxidized to nickel oxide (NiO). Ｏ２ is 10 －３ ~10 －６The wiring region A1 is heat-treated so that the oxygen partial pressure is in the order of 10 Pa. －１ By performing heat treatment at a pressure of at least Pa, the metal (titanium) constituting the metal layer 116 is oxidized and transformed into the low dielectric layer 115, and then the metal (nickel) constituting the upper electrode adhesion layer 113 and titanium, the metal forming the low dielectric layer 115, form a covalent bond via oxygen. As a result, strong adhesion can be obtained between the layers.

[0035] 5B, a low dielectric layer 115 is formed on the upper surface of the piezoelectric layer 112 in the wiring region A1, and an upper electrode adhesion layer 113 is formed on the upper surface of the low dielectric layer 115 in the wiring region A1. Furthermore, because the metal layer 116 is transformed into the low dielectric layer 115 by the heat treatment in this manner and the low dielectric layer 115 and the piezoelectric layer 112 contain titanium as a common element, interfacial mixing is likely to occur between the low dielectric layer 115 and the piezoelectric layer 112, thereby increasing the adhesion between the piezoelectric layer 112 and the low dielectric layer 115.

[0036] Furthermore, by applying heat to the wiring region A1, the metal (nickel) constituting the upper electrode adhesion layer 113 in the wiring region A1 and the metal (titanium in the first embodiment) constituting the low dielectric layer 115 in the wiring region A1 are covalently bonded via oxygen atoms. As a result, the upper electrode adhesion layer 113 and the low dielectric layer 115 are in close contact with each other in the wiring region A1. Similarly, heat is applied to the drive region A2. As a result, the metal (nickel) constituting the upper electrode adhesion layer 113 in the drive region A2 and the metal (titanium or lead) constituting the piezoelectric layer 112 in the drive region A2 are covalently bonded via oxygen atoms. As a result, the upper electrode adhesion layer 113 and the piezoelectric layer 112 are in close contact with each other in the drive region A2.

[0037] 5(a), the upper surface of the metal layer 116 in the wiring region A1 and the upper surface of the piezoelectric layer 112 in the drive region A2 are at substantially the same height, and therefore, even in the state shown in FIG. 5(b), the upper surface of the low dielectric layer 115 in the wiring region A1 and the upper surface of the piezoelectric layer 112 in the drive region A2 are also at substantially the same height. As a result, the upper and lower surfaces of the upper electrode adhesion layer 113 in the wiring region A1 are at substantially the same height as the upper and lower surfaces of the upper electrode adhesion layer 113 in the drive region A2, respectively.

[0038] 5B, an upper electrode 114 is formed on the upper surface of the upper electrode adhesive layer 113. In this way, the laminated structure 110 shown in FIG.

[0039] <Effects of First Embodiment> According to the first embodiment, the following effects are achieved.

[0040] In the wiring area A1 on the fixed part 10 side of the upper surface areas of the fixed part 10 and the driving part 20, as shown in Figure 2, a low dielectric layer 115 containing at least one element (component of the piezoelectric layer 112) that forms the piezoelectric layer 112 is formed on the upper surface of the piezoelectric layer 112.

[0041] According to this configuration, the low-dielectric layer 115 is formed on the top surface of the piezoelectric layer 112 in the wiring area A1, causing a voltage drop in the wiring area A1 due to the low-dielectric layer 115, thereby reducing the voltage applied to the piezoelectric layer 112 in the wiring area A1. This suppresses unnecessary displacement and stress in the wiring area A1, preventing damage to the wiring area A1 and improving the reliability of the driving element 1. Furthermore, suppressing the voltage to the piezoelectric layer 112 in the wiring area A1 reduces the power consumption of the driving unit 20.

[0042] Furthermore, because the low dielectric layer 115 and the piezoelectric layer 112 contain the same component (titanium in the first embodiment), interfacial mixing between the low dielectric layer 115 and the piezoelectric layer 112 is likely to occur by heat treatment, thereby improving the adhesion between the low dielectric layer 115 and the piezoelectric layer 112. This prevents the low dielectric layer 115 from peeling off from the top surface of the piezoelectric layer 112, thereby improving the reliability of the driving element 1.

[0043] The low dielectric layer 115 is formed by thermally reacting the metal layer 116 provided on the piezoelectric layer 112 with the piezoelectric layer 112. As described above, the thermal reaction is a process in which the titanium in the metal layer 116 is converted into PbTiO ｘ This is a reaction that changes the metal layer 116 into PbTiO ｘ By changing the dielectric layer 115 to one containing titanium or titanium dioxide, the low dielectric layer 115 and the piezoelectric layer 112 contain titanium or lead as common elements, causing interfacial mixing between the low dielectric layer 115 and the piezoelectric layer 112. This makes it difficult for the low dielectric layer 115 to peel off from the top surface of the piezoelectric layer 112.

[0044] The closer the metal layer 116 is to the piezoelectric layer 112, the more likely a thermal reaction occurs between the metal layer 116 and the piezoelectric layer 112. Therefore, the closer the low-dielectric layer 115 is to the piezoelectric layer 112, the more components of the piezoelectric layer 112 (such as elements such as titanium and lead) it contains, causing interfacial mixing between the low-dielectric layer 115 and the piezoelectric layer 112 and the components of the piezoelectric layer 112. This makes the interface between the low-dielectric layer 115 and the piezoelectric layer 112 unclear, allowing external stress to be dispersed. This makes it possible to prevent peeling due to external stress.

[0045] An upper electrode adhesion layer 113 is disposed on the upper surface of the low-dielectric layer 115 in the wiring region A1 and on the upper surface of the piezoelectric layer 112 in the drive region A2. With this configuration, in the wiring region A1, the metal atoms (nickel) of the upper electrode adhesion layer 113 and the metal atoms (titanium in the first embodiment) of the low-dielectric layer 115 are covalently bonded via oxygen atoms by heat treatment, thereby bonding the upper electrode adhesion layer 113 and the low-dielectric layer 115 together. Furthermore, in the drive region A2, the metal atoms (nickel) of the upper electrode adhesion layer 113 and the metal atoms (titanium in the first embodiment) of the piezoelectric layer 112 are covalently bonded via oxygen atoms by heat treatment, thereby bonding the upper electrode adhesion layer 113 and the piezoelectric layer 112 together. This prevents peeling of the upper electrode adhesion layer 113.

[0046] Furthermore, since the upper electrode adhesion layer 113 is disposed between the upper electrode 114 and the piezoelectric layer 112, the adhesion force on the upper surface of the piezoelectric layer 112 can be increased compared to when the upper electrode adhesion layer 113 is not disposed. This makes it possible to suppress peeling of the upper electrode 114 due to stress or external force when the piezoelectric layer 112 is driven, thereby improving the reliability of the driving element 1.

[0047] The metal (titanium) contained in the low-dielectric layer 115 has a smaller standard reaction Gibbs energy of oxide than the metal (nickel) contained in the upper electrode adhesion layer 113. In this way, materials for forming each layer are selected so that the standard reaction Gibbs energy of oxide of the low-dielectric layer 115 is smaller than the standard reaction Gibbs energy of oxide of the upper electrode adhesion layer 113, and the oxygen partial pressure during the oxidation heat treatment is adjusted as described above. This makes it possible to make the metal (titanium) of the low-dielectric layer 115 a dielectric while suppressing oxidation of the upper electrode adhesion layer 113 (nickel) during the heat treatment of the metal layer 116 (titanium), and also improve the adhesion between the upper electrode adhesion layer 113 and the low-dielectric layer 115 by the subsequent heat treatment.

[0048] The top surface of the low-dielectric layer 115 in the wiring region A1 and the top surface of the piezoelectric layer 112 in the drive region A2 are at approximately the same height. With this configuration, the upper electrode 114 in the wiring region A1 and the upper electrode 114 in the drive region A2 are connected at approximately the same height, which reduces stress on the boundary between the wiring region A1 and the drive region A2 when the drive element 1 is driven, compared to when there is a step at the boundary between the wiring region A1 and the drive region A2. This prevents disconnection of the upper electrode 114 across the wiring region A1 and the drive region A2. Furthermore, when there is a step between the top surface of the low-dielectric layer 115 in the wiring region A1 and the top surface of the piezoelectric layer 112 in the drive region A2, the thickness of the upper electrode adhesion layer 113 and the upper electrode 114 near the boundary of the step is likely to vary compared to the thickness of the other portions. In contrast, in the first embodiment, such a step does not occur, so the thicknesses of the upper electrode adhesion layer 113 and the upper electrode 114 are substantially uniform throughout the entire wiring region A1 and the drive region A2. This allows the resistance of the upper electrode 114 to be set to substantially the same value. This allows the resistance of the upper electrode 114 to be stabilized.

[0049] If the upper surfaces of the upper electrodes 114 in the wiring region A1 and the driving region A2 are connected at different heights, the upper electrodes 114 that straddle the wiring region A1 and the driving region A2 are prone to breakage, and to avoid this, it is necessary to increase the thickness of the upper electrodes 114. In contrast, according to the configuration of embodiment 1, the upper electrodes 114 in the wiring region A1 and the driving region A2 are connected at approximately the same height, which prevents breakage and allows the thickness of the upper electrodes 114 to be thin.

[0050] <Embodiment 2> In embodiment 1, the low dielectric layer 115 is formed by thermally reacting the metal layer 116, but in embodiment 2, the low dielectric layer 115 is formed by ion implantation into the piezoelectric layer 112. The procedure for forming the low dielectric layer 115 will be described below.

[0051] As shown in FIG. 6A, a resist layer 117 is formed on the top surface of the piezoelectric layer 112 in the driving region A2 of the piezoelectric layer 112 in FIG. 3A. In this state, ions are implanted into the piezoelectric layer 112 exposed above the wiring region A1. The implanted ions are atoms of the B site of the perovskite structure, and include at least one of titanium (Ti), zirconium (Zr), niobium (Nb), zinc (Zn), and magnesium (Mg). This forms PZT (Pb(Zr,Ti)O) constituting the piezoelectric layer 112. ３ ) defects occur in the perovskite structure.

[0052] 6A, when ion implantation into the piezoelectric layer 112 in the wiring region A1 is completed, the resist layer 117 arranged on the top surface of the piezoelectric layer 112 in the driving region A2 is removed as shown in FIG. 6B. After the resist is removed, heat is applied to the piezoelectric layer 112 in the wiring region A1. By performing heat treatment on the piezoelectric layer 112 where defects have occurred in the perovskite structure, a pyrochlore structure is formed in this portion.

[0053] The pyrochlore structure has a lower dielectric constant than the perovskite structure and does not have piezoelectricity. In this way, the piezoelectric layer 112 in the wiring region A1 changes into a low-dielectric layer 115 having a low dielectric constant. The composition ratio of the pyrochlore structure is, for example, A ２ B ２ O ７ The low dielectric layer 115 is formed by modifying the piezoelectric layer 112 through ion implantation and heat treatment, and therefore contains components (atoms of titanium, lead, etc.) that are common to the piezoelectric layer 112 even after the change to the pyrochlore structure.

[0054] In this case, as in the first embodiment, the top surface of the low dielectric layer 115 in the wiring region A1 and the top surface of the piezoelectric layer 112 in the driving region A2 are at approximately the same height. Next, an upper electrode adhesion layer 113 made of nickel is formed over the entire top surfaces of the wiring region A1 and the driving region A2, and heat is applied to form an upper electrode 114 on the top surface of the upper electrode adhesion layer 113. In this way, the laminate structure 110 shown in FIG. 2 is completed.

[0055] <Effects of Second Embodiment> According to the second embodiment, the following effects are achieved.

[0056] In the second embodiment, as in the first embodiment, a low-dielectric layer 115 containing at least one element (a component of the piezoelectric layer 112) forming the piezoelectric layer 112 is formed on the upper surface of the piezoelectric layer 112 in the wiring region A1, as shown in FIG. 2 . The low-dielectric layer 115 in the second embodiment is formed by ion implantation and heat treatment of a portion of the piezoelectric layer 112. Therefore, the low-dielectric layer 115 is a dielectric material having a lower dielectric constant than that of the original piezoelectric layer 112 and not exhibiting piezoelectricity. Therefore, as in the first embodiment, a voltage drop occurs due to the low-dielectric layer 115 in the wiring region A1, thereby reducing the voltage applied to the piezoelectric layer 112 in the wiring region A1. This suppresses unnecessary displacement and stress in the wiring region A1, thereby avoiding damage to the wiring region A1 and improving the reliability of the driving element 1.

[0057] Also in the second embodiment, since the low dielectric layer 115 and the piezoelectric layer 112 contain the same components (titanium and lead in the second embodiment), interfacial mixing is likely to occur between the low dielectric layer 115 and the piezoelectric layer 112, and the adhesion between the low dielectric layer 115 and the piezoelectric layer 112 can be improved.

[0058] The low-dielectric layer 115 is formed by ion implantation and heat treatment into the piezoelectric layer 112. The ion implantation can cause defects in the perovskite structure that constitutes the piezoelectric layer 112. Furthermore, the heat treatment imparts oxygen to the perovskite structure with defects, thereby forming a pyrochlore structure. This allows the piezoelectric layer 112 that has been subjected to ion implantation and heat treatment to be transformed into the low-dielectric layer 115.

[0059] The ions implanted into the piezoelectric layer 112 when forming the low dielectric layer 115 are atoms in the B site of the perovskite structure, and contain, for example, at least one of titanium (Ti), zirconium (Zr), niobium (Nb), zinc (Zn), and magnesium (Mg). This allows excess A site vacancies to be generated in the vacant perovskite structure of the piezoelectric layer 112, making it possible to easily form a pyrochlore structure by subsequent heat treatment.

[0060] Because ion implantation is performed on the piezoelectric layer 112 exposed upward in the wiring region A1, the closer to the top surface of the piezoelectric layer 112, the more likely the piezoelectric layer 112 is to develop a pyrochlore structure due to the effects of ion implantation and heat treatment. Therefore, the low-dielectric layer 115 contains more of the structure of the piezoelectric layer 112 (perovskite structure) as it progresses downward from the top surface of the piezoelectric layer 112 (as it approaches the piezoelectric layer 112 located below the low-dielectric layer 115). Therefore, the interface between the low-dielectric layer 115 and the piezoelectric layer 112 becomes unclear, allowing external stress acting on the interface to be dispersed. This makes it possible to prevent peeling due to external stress.

[0061] <Embodiment 3> In embodiment 1, the low dielectric layer 115 is configured by one layer, but in embodiment 3, it is configured by two layers. The procedure for forming the low dielectric layer 115 will be described below.

[0062] A metal layer 116 and a low-dielectric layer 118 similar to those in the first embodiment are laminated in this order on the piezoelectric layer 112 of Fig. 3(b), and the metal layer 116 and the low-dielectric layer 118 laminated in areas other than the wiring area A1 are removed. As a result, as shown in Fig. 7(a), the metal layer 116 and the low-dielectric layer 118 are laminated only on the top surface of the piezoelectric layer 112 in the wiring area A1. At this time, the top surface of the low-dielectric layer 118 is set to be at approximately the same height as the top surface of the piezoelectric layer 112 in the driving area A2. The low-dielectric layer 118 is made of alumina (Al ２ O ３ ), silicon dioxide (SiO ２ ), silicon nitride (Si ３ N ４ ), silicon oxynitride (SiON), etc.

[0063] Next, heat is applied to the metal layer 116 and the low-dielectric layer 118 in the wiring region A1. As a result, as shown in FIG. 7B, the metal layer 116 is transformed into the low-dielectric layer 115, as in the first embodiment. At this time, the low-dielectric layer 118 is formed in an oxidized or nitrided state, so its composition is not substantially changed by the heat. Furthermore, the upper surface of the low-dielectric layer 118 in the wiring region A1 and the upper surface of the piezoelectric layer 112 in the drive region A2 are substantially flush with each other. Then, as shown in FIG. 7B, as in the first embodiment, an upper electrode adhesion layer 113 made of nickel is formed over the entire upper surface of the wiring region A1 and the drive region A2, and heat is applied. Thereafter, an upper electrode 114 is formed on the upper surface of the upper electrode adhesion layer 113. In this manner, the laminate structure 110 shown in FIG. 2 is completed.

[0064] 2, in the wiring region A1, a low-dielectric layer 115 containing at least one element (a component of the piezoelectric layer 112) that forms the piezoelectric layer 112 is formed on the upper surface of the piezoelectric layer 112. Therefore, as in the first embodiment, a voltage drop occurs in the wiring region A1 due to the low-dielectric layer 115, and the voltage applied to the piezoelectric layer 112 in the wiring region A1 can be reduced. This suppresses unnecessary displacement or stress in the wiring region A1, thereby preventing damage to the wiring region A1 and improving the reliability of the driving element 1.

[0065] The low-dielectric layer in the wiring region A1 is multi-layered. That is, in the wiring region A1, low-dielectric layers 115 and 118 are stacked and disposed between the piezoelectric layer 112 and the upper electrode adhesive layer 113. When the low-dielectric layer 118 is made of the above-mentioned material, the relative dielectric constant of the low-dielectric layer 118 can be made even smaller than that of the low-dielectric layer 115. This allows the voltage applied to the piezoelectric layer 112 in the wiring region A1 to be further reduced.

[0066] Furthermore, in the piezoelectric layer 112 and the low dielectric layer 115, similarly to the first embodiment, the same components cause interfacial mixing between the low dielectric layer 115 and the piezoelectric layer 112, thereby improving the adhesion between the piezoelectric layer 112 and the low dielectric layer 115. Furthermore, when the low dielectric layer 118 is made of alumina, silicon dioxide, or silicon oxynitride, aluminum atoms and silicon atoms are covalently bonded to metal atoms (titanium or lead) of the low dielectric layer 115 via oxygen atoms or nitrogen atoms, respectively, thereby enabling the low dielectric layers 115 and 118 to adhere to each other.

[0067] Fourth Embodiment In the first embodiment, the pair of drive units 20 has a tuning fork shape, but in the fourth embodiment, the pair of drive units 20 has a meander shape.

[0068] FIG. 8 is a plan view schematically showing the configuration of a driving element 1 according to the fourth embodiment.

[0069] The driving element 1 includes a pair of fixed parts 210, a pair of driving parts 220, and a movable part 230. The driving element 1 is configured to be point symmetrical with respect to a center 230a of the movable part 230. When driven by the driving part 220, the movable part 230 rotates about a rotation axis R10 that passes through the center 230a and extends in the X-axis direction.

[0070] The pair of fixed portions 210 are aligned in the direction of the rotation axis R10. When the driving element 1 is installed, the surface on the negative side of the Z axis of the fixed portion 210 (the surface on the negative side of the Z axis of the base portion 101 in FIG. 2) is installed at the installation location.

[0071] The pair of drive units 220 have a meandering shape. The pair of drive units 220 are aligned in the direction of the rotation axis R10, aligned beside the pair of fixed units 210, and connected to the fixed units 210. The drive unit 220 includes a plurality of vibration units 221, a plurality of connection units 222, and a connection unit 223. The plurality of vibration units 221 extend in the Y-axis direction and are aligned at intervals in the X-axis direction. Two adjacent vibration units 221 are connected at their ends in the Y-axis direction by a connection unit 222 extending in the X-axis direction. The outer end of the connection unit 223 (the end away from the center 230a) is connected to the end of the innermost vibration unit 221 in the Y-axis direction, and the inner end of the connection unit 223 (the end close to the center 230a) is connected to the movable unit 230.

[0072] A mirror 231 is provided on the surface on the positive side of the Z axis of the movable part 230. The movable part 230 and the mirror 231 have the same configuration as the movable part 30 and the mirror 31 of the first embodiment.

[0073] A laminated structure 110 similar to any one of the first to third embodiments is arranged on the upper surface regions of the fixed section 210 and the drive section 220. Of the two laminated structures 110 aligned in the Y-axis direction, one laminated structure 110 is formed so that its area is larger on every other vibrating section 221 (first vibrating section group), and the other laminated structure 110 is formed so that its area is larger on the vibrating section 221 (second vibrating section group) where the area of ​​one laminated structure 110 is smaller. The end of the laminated structure 110 on the fixed section 210 side is connected to an external power supply or the like. When the drive section 220 is driven, voltages of opposite phases are applied to the first vibrating section group and the second vibrating section group (two laminated structures 110) so that the first vibrating section group and the second vibrating section group vibrate in opposite directions in the Z-axis direction. As a result, the movable portion 230 and the mirror 231 rotate about the rotation axis R10, and the direction of light incident on the mirror 231 is changed according to the rotation angle of the mirror 231.

[0074] In the fourth embodiment, the fixed portion 210, the connecting portion 222, and the portion of the vibrating portion 221 where the area of ​​the laminated structure 110 is small are the wiring region A1. The portion of the vibrating portion 221 where the area of ​​the laminated structure 110 is large is the driving region A2.

[0075] In the fourth embodiment, the laminated structure 110 is also disposed across the wiring region A1 and the driving region A2. Furthermore, when a section from the position of the fixed portion 210 in the wiring region A1 to the position of the driving portion 220 in the driving region A2 is cut along a cross section parallel to the X-Z plane and a cross section parallel to the Y-Z plane, the cross section is the same as that shown in FIG. 2. That is, in the fourth embodiment, the configuration of the laminated structure 110 in the wiring region A1 and the configuration of the laminated structure 110 in the driving region A2 are the same as those in the first embodiment, and the configuration of the laminated structure 110 spanning the wiring region A1 and the driving region A2 is also the same as those in the first embodiment. Therefore, the fourth embodiment also achieves the same effects as those in the first embodiment.

[0076] Fifth Embodiment In a fifth embodiment, compared to the first to third embodiments, a configuration for detecting the driving of the driving unit 20 is further added.

[0077] Fig. 9 is a plan view schematically illustrating the configuration of the driving element 1 according to embodiment 5. For convenience, Fig. 9 illustrates the first wiring region A11, the second wiring region A12, the driving region A2, and the sensing region A3 by hatching or the like so that each region can be distinguished.

[0078] In the fifth embodiment, the upper surface areas of the fixed unit 10 and the drive unit 20 are divided into a first wiring area A11, a second wiring area A12, a drive area A2, and a detection area A3. The drive area A2 is an area for driving the vibration unit 21. The detection area A3 is an area for detecting the displacement of the drive area A2. The pair of the drive area A2 and the detection area A3 arranged on one vibration unit 21 drives the vibration unit 21 and detects the displacement of the vibration unit 21.

[0079] The driving area A2 is disposed in a portion of the vibrating unit 21 extending in the X-axis direction and is a rectangular area in a plan view. The detection area A3 is disposed in a portion of the vibrating unit 21 extending in the Y-axis direction and is a rectangular area in a plan view.

[0080] The wiring region A1 is divided into a first wiring region A11 and a second wiring region A12. The first wiring region A11 extends from the driving region A2 to the fixed portion 10 via the connection portion 22. The second wiring region A12 extends from the detection region A3 to the fixed portion 10 via the connection portion 22.

[0081] The laminated structure 110a formed in the region consisting of the driving region A2 and the first wiring region A11 is similar to the laminated structure 110 of the first to third embodiments. A low-dielectric layer 115 (or low-dielectric layers 115, 118) is arranged in the first wiring region A11, but the low-dielectric layer 115 (or low-dielectric layers 115, 118) is not arranged in the driving region A2. The laminated structure 110b formed in the region consisting of the sensing region A3 and the second wiring region A12 is similar to the laminated structure 110 of any one of the first to third embodiments. A low-dielectric layer 115 (or low-dielectric layers 115, 118) is arranged in the second wiring region A12, but the low-dielectric layer 115 (or low-dielectric layers 115, 118) is not arranged in the sensing region A3. The laminated structures 110a and 110b are formed by the same method as the formation method shown in the first to third embodiments.

[0082] FIG. 10 is a diagram schematically showing a cross section taken along the line C3-C4 of FIG.

[0083] For convenience, Fig. 10 shows a cross section of the C3-C4 cross section located on the positive side of the Y-axis of the rotation axis R10. Also, Fig. 10 shows a position P2 on the C3-C4 cross section, which indicates the boundary between the second wiring region A12 and the detection region A3. Fig. 10 shows a cross section in the case where the stacked structures 110a and 110b are formed by either of the above-described first and second embodiments.

[0084] FIG. 11 is a block diagram showing the configuration of the driving element 1 and an external device 2 connected to the driving element 1.

[0085] 11 shows, for convenience, a set of a driving region A2 and a sensing region A3 arranged in one vibration unit 21, and a first wiring region A11 and a second wiring region A12 connected to them. The external device 2 is provided with a circuit unit shown in FIG. 11 for each vibration unit 21.

[0086] The external device 2 includes a detection circuit 2a, a determination circuit 2b, and a drive circuit 2c. The detection circuit 2a is connected to the second wiring area A12, and the drive circuit 2c is connected to the first wiring area A11. The drive circuit 2c applies a sinusoidal drive voltage to the piezoelectric layer 112 of the drive area A2 via the first wiring area A11, causing the vibration unit 21 to vibrate. When the vibration unit 21 vibrates, the electric charge generated in the laminate structure 110b of the detection area A3 changes due to the piezoelectric effect (d31) of the piezoelectric layer 112 of the vibration unit 21. The detection circuit 2a converts the electric charge in the detection area A3, which changes in response to the vibration of the vibration unit 21, into a voltage signal and outputs a detection signal reflecting the change in the electric charge to the determination circuit 2b.

[0087] The determination circuit 2b determines whether the detection signal input from the detection circuit 2a matches the waveform of the reference signal. The waveform of the reference signal is the ideal waveform of the detection signal output from the detection circuit 2a when the movable part 30 vibrates at the target frequency and amplitude. The determination circuit 2b outputs a control signal to the drive circuit 2c so that the amplitude of the detection signal output from the detection circuit 2a matches the amplitude of the reference voltage, as shown in FIG. 12(a), and so that the period of the detection signal output from the detection circuit 2a matches the period of the reference voltage, as shown in FIG. 12(b). The drive circuit 2c corrects the drive voltage applied to the piezoelectric layer 112 in the drive region A2 based on the control signal output from the determination circuit 2b, and applies the corrected drive voltage to the piezoelectric layer 112 in the drive region A2.

[0088] This control allows the driving unit 20 to vibrate at an appropriate vibration amplitude even if the piezoelectric characteristics of the piezoelectric layer 112 change due to deterioration or temperature characteristics. Furthermore, this control allows the driving unit 20 to vibrate at an appropriate frequency even if the device layer 102 constituting the driving element 1 becomes fatigued or the resonant frequency of the driving element 1 changes due to temperature changes.

[0089] Here, if the capacitance of the detection area A3 is Cd, the capacitance of the second wiring area A12 is Cw, and the change in charge caused by the vibration of the vibrating part 21 is ΔC, the S / N ratio of the detection accuracy of the detection circuit 2a can be expressed as ΔC / (Cd+Cw). Therefore, the detection accuracy of the detection circuit 2a can be improved by reducing the capacitances Cd and Cw.

[0090] However, reducing the capacitance Cd of the detection region A3 also reduces the charge change ΔC. In contrast, reducing the capacitance Cw of the second wiring region A12 does not significantly reduce the charge change ΔC because the second wiring region A12 includes a wiring region on the fixed portion 10 where no piezoelectric effect due to vibration occurs. According to the fifth embodiment, the low-dielectric layer 115 (or low-dielectric layers 115, 118) is disposed in the second wiring region A12, so only the capacitance Cw of the second wiring region A12 is reduced. Therefore, according to the fifth embodiment, the S / N ratio can be increased, and the drive control of the vibrating portion 21 can be performed more accurately.

[0091] Effect of Embodiment 5 In embodiment 5, as in embodiments 1 to 3, in any of the wiring regions A1, a low-dielectric layer 115 (or low-dielectric layers 115, 118) containing at least one element (a component of the piezoelectric layer 112) that forms the piezoelectric layer 112 is formed on the upper surface of the piezoelectric layer 112. Therefore, as in embodiments 1 to 3, a voltage drop occurs due to the low-dielectric layer in any of the wiring regions A1, and the voltage applied to the piezoelectric layer 112 in the wiring region A1 can be reduced. This suppresses unnecessary displacement or stress in the wiring region A1, thereby avoiding damage to the wiring region A1 and improving the reliability of the driving element 1.

[0092] The area on the driver 20 side of the top surface area of ​​the fixed unit 10 and the driver 20 is divided into a drive area A2 for driving and a detection area A3 for detecting displacement of the drive area A2, and the wiring area A1 on the top surface area on the fixed unit 10 side is divided into a first wiring area A11 connected to the drive area A2 and a second wiring area A12 connected to the detection area A3. This makes it possible to detect the driving state of the vibrating unit 21 (drive unit 20) using a detection signal based on the detection area A3.

[0093] 11 to 12(b), the determination circuit 2b uses the detection signal based on the detection area A3 to output a control signal to the drive circuit 2c for correcting the amplitude and frequency of the voltage applied to the drive area A2. This allows the vibration unit 21 to vibrate with an appropriate vibration amplitude and frequency, and the drive states of the movable unit 30 and the mirror 31 can be set to desired states.

[0094] Furthermore, since the low dielectric layer 115 (or the low dielectric layers 115, 118) is disposed in the second wiring region A12, the capacitance Cw of the second wiring region A12 can be effectively reduced. This increases the signal-to-noise ratio, allowing the external device 2 to accurately detect changes in charge based on the detection region A3.

[0095] Modification of Fifth Embodiment The layout of the driving region A2 and the detection region A3 is not limited to the layout shown in FIG. 9, and other layouts may be used.

[0096] Fig. 13(a) is a plan view schematically showing the configuration of the driving element 1 according to Modification 1 of Embodiment 5. The driving element 1 according to Modification 1 is configured to be line-symmetric in the X-axis direction with the movable part 30 at the center, and therefore, for convenience, only the portion of the movable part 30 on the negative side of the X-axis is shown in Fig. 13(a).

[0097] 13A, the driving region A2 and the detection region A3 are both L-shaped. In this case, the low-dielectric layer is not disposed in the driving region A2 or the detection region A3, but is disposed in the wiring region A1.

[0098] Fig. 13B is a plan view schematically showing the configuration of the driving element 1 according to Modification 2 of Embodiment 5. In Fig. 13B as well, for convenience, only the portion of the movable part 30 on the negative side of the X axis is shown.

[0099] In Modification Example 2 of FIG. 13( b), one drive region A2 is arranged in a portion of the vibrating unit 21 extending in the X-axis direction, and another drive region A2 is arranged in a portion of the vibrating unit 21 extending in the Y-axis direction. A first wiring region A11 connected to the fixed unit 10 is connected to the drive region A2 closer to the rotation axis R10, and the two drive regions A2 are connected by another first wiring region A11. Similarly, one detection region A3 is arranged in a portion of the vibrating unit 21 extending in the X-axis direction, and another detection region A3 is arranged in a portion of the vibrating unit 21 extending in the Y-axis direction. A second wiring region A12 connected to the fixed unit 10 is connected to the detection region A3 closer to the rotation axis R10, and the two detection regions A3 are connected by another second wiring region A12. The other first wiring region A11 and other second wiring region A12 are configured similarly to the wiring region A1 and have a low-dielectric layer.

[0100] The configurations of these modified examples 1 and 2 can also achieve the same effects as those of the fifth embodiment.

[0101] Sixth Embodiment In a sixth embodiment, the driving unit 20 of the driving element 1 is configured to have a meandering shape, similar to the fourth embodiment. Furthermore, in the sixth embodiment, a detection area A3 for detecting the driving of the driving unit 20 is formed, similar to the fifth embodiment.

[0102] FIG. 14 is a plan view schematically showing the configuration of a driving element 1 according to a sixth embodiment.

[0103] In the driving element 1 of embodiment 6, compared to embodiment 4, the detection regions A3 are arranged in the two outermost vibration sections 221 of the three vibration sections 221 aligned in the X-axis direction. The two detection regions A3 are each connected to the fixed section 10 by separate second wiring regions A12. Furthermore, unlike embodiment 4, the driving element 1 of embodiment 6 is configured to be linearly symmetrical about the movable section 230 in the X-axis direction. Therefore, the end of the movable section 230 on the negative side of the Y-axis is supported by the driving section 220 on the positive side of the X-axis and the driving section 220 on the negative side of the X-axis. Each wiring region A1 of embodiment 6 has a low-dielectric layer, as in embodiments 1 to 5 above.

[0104] In the sixth embodiment, among the vibration units 221 arranged in the X-axis direction, the vibration unit 221 adjacent to the fixed unit 210 and the vibration unit 221 adjacent to the movable unit 230 are referred to as the first vibration unit, and the vibration unit 221 sandwiched between the first vibration units is referred to as the second vibration unit. When the drive unit 220 is driven, voltages of opposite phases are applied to the drive region A2 of the first vibration unit and the drive region A2 of the second vibration unit so that the first vibration unit and the second vibration unit vibrate in opposite directions in the Z-axis direction. At this time, a signal based on the outer detection region A3 corrects the drive voltage applied to the drive region A2 of the first vibration unit, thereby controlling the drive of the first vibration unit. On the other hand, a signal based on the inner detection region A3 corrects the drive voltage applied to the drive region A2 of the second vibration unit, thereby controlling the drive of the second vibration unit.

[0105] In the sixth embodiment, the same effects as those in the fourth and fifth embodiments are achieved.

[0106] In the first and third embodiments, the metal layer 116 is made of titanium, but the metal layer 116 may be made of any metal that can be converted into a low dielectric layer by a thermal reaction. For example, the metal layer 116 may be made of zirconium, niobium, zinc, magnesium, or the like.

[0107] In the first to sixth embodiments, the piezoelectric layer 112 is made of PZT (Pb (Zr, Ti) O ３ ), but is not limited to this, for example, PbZrO ３ , PbTiO ３ , Pb(Mg １／３ , Nb ２／３ ) O ３ , or Pb(Zn １／３ , Nb ２／３ ) O ３ That is, the piezoelectric layer 112 may be PbZrO ３ , PbTiO ３ , Pb(Zr,Ti)O ３ , Pb(Mg １／３ , Nb ２／３ ) O ３ , and Pb(Zn １／３ , Nb ２／３ ) O ３ For example, Pb(Mg １／３ , Nb２／３ ) O ３ and Pb(Zn １／３ , Nb ２／３ ) O ３ is PbZrO ３ and PbTiO ３ In this case, the piezoelectric constant is improved by using at least one of Pb(Mg １／３ , Nb ２／３ ) O ３ and Pb(Zn １／３ , Nb ２／３ ) O ３ The driving force and driving amount of the driving element 1 can be improved compared to when the driving element 1 is used alone.

[0108] Furthermore, the piezoelectric layer 112 is made of BiFeO ３ and KNbO ３ When a lead-free ferroelectric material is used as the piezoelectric layer 112, in the first and third embodiments, the material of the metal layer 116 is appropriately selected in accordance with the material of the piezoelectric layer 112, and in the second embodiment, ion implantation and heat treatment are performed in the same manner as above, thereby achieving the same effects as above.

[0109] In the first to sixth embodiments, the lower electrode 111 is made of platinum and the upper electrode 114 is made of gold, but the materials constituting the lower electrode 111 and the upper electrode 114 are not limited to these. For example, the lower electrode 111 may be made of iridium, lanthanum nickel oxide (LaNiO ３ ), strontium ruthenate (SrRuO ３ ) or the like. A lower electrode adhesion layer may be provided between the device layer 102 and the lower electrode 111. For example, the upper electrode 114 may be made of platinum, aluminum, molybdenum, tungsten, iridium, lanthanum nickelate (LaNiO ３ ), strontium ruthenate (SrRuO ３ ) or the like. Although the upper electrode adhesion layer 113 is made of nickel, the material constituting the upper electrode adhesion layer 113 is not limited to this. For example, the upper electrode adhesion layer 113 may be made of titanium, tungsten, or chromium.

[0110] In the second embodiment, the upper part of the piezoelectric layer 112 is transformed into the low dielectric layer 115 by ion implantation and heat treatment, but the heat treatment may be omitted and only ion implantation may be performed on the upper part of the piezoelectric layer 112. In this case as well, defects occur in the perovskite structure in the upper part of the piezoelectric layer 112, and this part becomes the low dielectric layer 115 that does not have piezoelectricity.

[0111] In the third embodiment, the low dielectric layer 115 is formed by applying heat to the metal layer 116, as in the first embodiment, but instead, it may be formed by ion implantation and heat treatment, as in the second embodiment.

[0112] In embodiments 1 to 6, a pair of fixed units 10 and a pair of driving units 20 are arranged in the X-axis direction with the movable unit 30 at the center, but the fixed unit 10 and the driving unit 20 may be arranged on only one side of the movable unit 30.

[0113] In the first to third embodiments, the vibrating units 21 and 221 are vibrated by supplying a voltage to the piezoelectric layer 112 in the driving region A2 from the fixed unit 10 and 210 side, but a voltage change generated in response to the vibration applied to the piezoelectric layer 112 in the driving region A2 may be output to the fixed unit 10 and 210 side. That is, in the first to third embodiments, an element having the configuration of the laminated structure 110 as described above may be used as a piezoelectric element that drives the vibrating unit 21 and detects the vibration of the vibrating unit 21. Similarly, in the fourth embodiment, an element having the configuration of the laminated structure 110 as described above may be used as a piezoelectric element that drives the vibrating unit 221 and detects the vibration of the vibrating unit 221. Furthermore, an element having the configuration of the laminated structure 110 as described above may be used as a piezoelectric element that detects only the vibration of the vibrating unit.

[0114] In addition, the embodiments of the present invention can be modified in various ways as appropriate within the scope of the technical ideas set forth in the claims.

[0115] REFERENCE SIGNS LIST 1 Drive element 10, 210 Fixed portion 20, 220 Drive portion 30, 230 Movable portion 31, 231 Mirror 111 Lower electrode 112 Piezoelectric layer 113 Upper electrode adhesion layer 114 Upper electrode 115 Low dielectric layer 116 Metal layer 118 Low dielectric layer A1 Wiring region A11 First wiring region A12 Second wiring region A2 Drive region

Claims

1. A driving element comprising: a fixed section; a driving section connected to the side of the fixed section; and a movable section driven by the driving section, wherein a lower electrode, a piezoelectric layer, and an upper electrode are formed in that order on the upper surface regions of the fixed section and the driving section; and further wherein, in the wiring region of the upper surface region on the fixed section side, a low dielectric layer containing at least one element that forms the piezoelectric layer is formed on the upper surface of the piezoelectric layer.

2. A driving element according to claim 1, characterized in that the low dielectric layer is formed by thermally reacting the piezoelectric layer with a metal layer provided on the piezoelectric layer.

3. A driving element according to claim 1, wherein the low dielectric layer is formed by ion implantation and heat treatment into the piezoelectric layer.

4. A driving element according to claim 3, wherein the ions to be implanted include at least one of titanium, zirconium, niobium, zinc, and magnesium.

5. In the driving element according to any one of claims 1 to 4, the piezoelectric layer is made of PbZrO ３ , PbTiO ３ , Pb(Zr,Ti)O ３ , Pb(Mg １／３ , Nb ２／３ ) O ３ , and Pb(Zn １／３ , Nb ２／３ ) O ３ A driving element comprising at least one of the following:

6. A driving element according to any one of claims 1 to 5, characterized in that the low dielectric layer contains more components or structures of the piezoelectric layer as it approaches the piezoelectric layer.

7. A driving element according to any one of claims 1 to 6, characterized in that an upper electrode adhesion layer is disposed on the upper surface of the low dielectric layer in the wiring region and on the upper surface of the piezoelectric layer in the driving region on the driving section side.

8. A driving element according to claim 7, wherein the metal contained in the low dielectric layer has a smaller standard reaction Gibbs energy of oxide than the upper electrode adhesion layer.

9. A driving element as claimed in any one of claims 1 to 8, characterized in that the upper surface of the low dielectric layer in the wiring region and the upper surface of the piezoelectric layer in the driving region on the driving unit side are at approximately the same height.

10. A driving element according to any one of claims 1 to 9, characterized in that the low dielectric layer is multi-layered.

11. The driving element according to any one of claims 1 to 10, wherein the driving portion is in the shape of a tuning fork.

12. A driving element according to any one of claims 1 to 10, characterized in that the driving section has a meandering shape.

13. A driving element as claimed in any one of claims 1 to 12, characterized in that the area of ​​the top surface on the driving unit side is divided into a driving area for driving and a detection area for detecting displacement of the driving area, and the wiring area of ​​the top surface on the fixed unit side is divided into a first wiring area connected to the driving area and a second wiring area connected to the detection area.

14. The driving element according to any one of claims 1 to 13, wherein a mirror is disposed on the movable part.