JP2007019290A - Piezoelectric thin film vibrator, method for manufacturing the same, drive device using the same, and piezoelectric motor - Google Patents

Abstract

The present invention relates to a piezoelectric thin film vibrator including a piezoelectric element formed by using a thin film forming technique, a manufacturing method thereof, and a driving device and a piezoelectric motor using the piezoelectric thin film vibrator, which can be manufactured at low cost. It is an object of the present invention to provide a child, a method for manufacturing the same, a driving device using the same, and a piezoelectric motor.
A resonator that generates traveling waves, a first electrode 3 formed by a thin film formation technique, a piezoelectric thin film 2 formed on the first electrode 3, and a piezoelectric thin film 2 formed on the piezoelectric thin film 2. The plurality of piezoelectric elements 1a to 1d and the piezoelectric elements 11a to 11d bonded to the resonator 4 and the plurality of piezoelectric elements 1a to 1d and the piezoelectric elements 11a to 11d are respectively connected to the resonator 4. And an adhesive layer 40 to be bonded.
[Selection] Figure 2

Description

  The present invention relates to a piezoelectric thin film vibrator including a piezoelectric element formed by using a thin film forming technique, a manufacturing method thereof, a driving device and a piezoelectric motor using the piezoelectric thin film vibrator.

  Piezoelectric thin film vibrators using the piezoelectric effect of piezoelectric elements are used in ultrasonic motors (piezoelectric motors), piezoelectric actuators, and the like. A piezoelectric element generally has a pair of electrodes and a piezoelectric thin film sandwiched between the electrodes.

  The piezoelectric element is formed by a thin film forming technique using a vapor deposition apparatus, a sputtering apparatus, a CVD apparatus, or the like. When the thin film forming technique is used, the element thickness of the piezoelectric element can be reduced, so that the applied voltage can be reduced and the entire piezoelectric element can be miniaturized.

  FIG. 16 shows a manufacturing method of the piezoelectric thin film vibrator 106 using a conventional thin film forming technique. As shown in FIGS. 16A and 16B, a first metal thin film (lower electrode) 103 is formed on a resonator 114 formed of a Si single crystal substrate. Next, as shown in FIG. 16C, a piezoelectric thin film 102 is formed on the first metal thin film 103. Next, as shown in FIG. 16D, a second metal thin film 133 is formed on the piezoelectric thin film 102. Next, as shown in FIG. 16E, the second metal thin film 133 is patterned into a predetermined shape to form a plurality of upper electrodes 113. Next, the resonator 114, the first metal thin film 103, and the piezoelectric thin film 102 are cut in a direction (vertical direction in the drawing) perpendicular to the plate surface of the resonator 114, whereby a plurality of piezoelectric thin film vibrators 106 are manufactured.

  When the disk-shaped piezoelectric thin film vibrator 106 is manufactured, a region of the Si single crystal substrate that is not used as the piezoelectric thin film vibrator 106 is necessarily formed between the plurality of adjacent piezoelectric thin film vibrators 106. In this region, the first electrode thin film 103, the piezoelectric film 102, and the second metal thin film 133 need to be formed, which raises a problem that the manufacturing cost increases.

  Further, since it is necessary to form the first electrode thin film 103, the piezoelectric film 102, and the second metal thin film 133 in a region where it is not necessary to form the piezoelectric element in the piezoelectric thin film vibrator 106, the manufacturing is performed. There is a problem that the cost becomes high.

JP-A-9-223824 JP 2000-332568 A

  An object of the present invention is to provide a piezoelectric thin film vibrator that can be manufactured at a low cost, a manufacturing method thereof, a driving device using the piezoelectric thin film vibrator, and a piezoelectric motor.

  The object is to generate a traveling wave, a first electrode formed by a thin film forming technique, a piezoelectric thin film formed on the first electrode, and a second electrode formed on the piezoelectric thin film. And a plurality of piezoelectric elements bonded on the resonator, and an adhesive layer for bonding each of the plurality of piezoelectric elements to the resonator. .

  The piezoelectric thin film vibrator according to the invention is characterized in that the piezoelectric thin film is an epitaxially grown film formed on the first electrode.

  In the piezoelectric thin film vibrator of the present invention, the plurality of piezoelectric elements belong to one of two piezoelectric element portions in different arrangement regions, and an interval between the bonding positions of the piezoelectric elements is the two piezoelectric elements. It is characterized by being equal in parts.

  The piezoelectric thin film vibrator according to the invention is characterized in that the resonator has a thin plate shape, and the plurality of piezoelectric elements are bonded to the front surface and the back surface of the resonator.

  The piezoelectric thin film vibrator according to the invention is characterized in that the piezoelectric element bonded to the back surface is bonded directly below the piezoelectric element bonded to the front surface.

  In the piezoelectric thin film vibrator according to the present invention, one of the two adjacent piezoelectric elements is bonded to the surface of the resonator, and the other is bonded to the back surface of the resonator.

  The piezoelectric thin film vibrator according to the present invention is characterized in that the piezoelectric thin film vibrator has a circular outer periphery, and the plurality of piezoelectric elements are arranged radially.

  In the piezoelectric thin film vibrator according to the invention, the shape of the piezoelectric element is rectangular when viewed in a direction perpendicular to the plate surface of the resonator.

  The piezoelectric thin film vibrator according to the invention is characterized in that the shape of the piezoelectric element is a sector when viewed in a direction perpendicular to the plate surface of the resonator.

  In the piezoelectric thin film vibrator according to the invention, the shape of the piezoelectric element is a trapezoid when viewed in a direction perpendicular to the plate surface of the resonator.

  The piezoelectric thin film vibrator according to the invention is characterized in that the resonator is made of metal.

  The piezoelectric thin film vibrator according to the invention is characterized in that the resonator is made of resin.

  Further, the above object is achieved by a driving device comprising the piezoelectric thin film vibrator of the present invention and an AC power supply that applies an AC voltage whose phase is shifted by a half period to the plurality of adjacent piezoelectric elements. The

  Further, the above object is achieved by a piezoelectric motor comprising a stator provided with the driving device of the present invention and a rotor disposed on the piezoelectric thin film vibrator.

  In addition, the object is to form a first metal thin film on a substrate, a piezoelectric thin film on the first metal thin film, and a second metal thin film on the piezoelectric thin film. An element layer is formed, the piezoelectric element layer is patterned into a predetermined shape, the piezoelectric element layer is divided into pieces to form a plurality of piezoelectric elements, and the plurality of piezoelectric elements are pasted on a resonator via an adhesive layer. This is achieved by a method of manufacturing a piezoelectric thin film vibrator characterized by matching.

  The method for manufacturing a piezoelectric thin film vibrator according to the present invention is characterized in that the piezoelectric thin film is formed on the first metal thin film by epitaxial growth.

  In the method of manufacturing a piezoelectric thin film vibrator according to the invention, the plurality of piezoelectric elements are bonded to one of two different arrangement regions to form two piezoelectric element portions, and the piezoelectric element is It is characterized in that two piezoelectric element portions are bonded at equal intervals.

  The method for manufacturing a piezoelectric thin film vibrator according to the present invention is characterized in that the plurality of piezoelectric elements are bonded to the front surface and the back surface of the resonator.

  The method for manufacturing a piezoelectric thin film vibrator according to the present invention is characterized in that the piezoelectric element to be bonded to the back surface is bonded directly below the piezoelectric element to be bonded to the front surface.

  The method for manufacturing a piezoelectric thin film vibrator according to the present invention is characterized in that one of the two adjacent piezoelectric elements is bonded to the surface of the resonator and the other is bonded to the back surface of the resonator.

  ADVANTAGE OF THE INVENTION According to this invention, the piezoelectric thin film vibrator which can be manufactured at low cost, its manufacturing method, a drive device and a piezoelectric motor using the same are realizable.

[First Embodiment]
A piezoelectric thin film vibrator and a method for manufacturing the same according to a first embodiment of the present invention, and a driving device and a piezoelectric motor using the same will be described with reference to FIGS. FIG. 1 is a perspective view showing a configuration of a piezoelectric thin film vibrator according to the present embodiment. FIG. 2 is a plan view of the piezoelectric thin film vibrator 6 according to the present embodiment. 3 is a cross-sectional view taken along line AA in FIG. As shown in FIGS. 1 to 3, the piezoelectric thin film vibrator 6 according to the present embodiment includes a resonator 4 that generates traveling waves, a first electrode 3 formed by a thin film formation technique, and a first electrode 3. A plurality of piezoelectric elements 1a to 1d and piezoelectric elements 11a to 11d, which are provided on the resonator 4 with a piezoelectric thin film 2 formed thereon and a second electrode 13 formed on the piezoelectric thin film 2; The piezoelectric elements 1a to 1d and the piezoelectric elements 11a to 11d are bonded to the resonator 4, respectively.

  The resonator 4 is formed in a thin plate shape and has a circular outer periphery. The resonator 4 is made of, for example, thermoplastic polycarbonate (PC), polyethylene terephthalate (PET), or a synthetic resin such as thermosetting phenol resin or epoxy resin, and has a thickness of about several tens of μm to 1 mm. A circular through hole 5 whose center substantially coincides with the center of the outer circumference circle 6 a of the piezoelectric thin film vibrator 6 is formed at the center of the piezoelectric thin film vibrator 6.

  As shown in FIG. 2, the piezoelectric element portions 1 and 11 are formed on the resonator 4 in different arrangement regions. The piezoelectric element portion 1 has rectangular parallelepiped piezoelectric elements 1a, 1b, 1c, and 1d having a long side length of, for example, 10 mm, a short side length of, for example, 1 mm, and a thickness of, for example, about 3 μm. is doing. That is, the shapes of the piezoelectric elements 1 a to 1 d are rectangular when viewed in the direction perpendicular to the plate surface of the resonator 4. The piezoelectric elements 1a to 1d are bonded with their long sides directed in the radial direction from the center of the piezoelectric thin film vibrator 6. Similarly, the piezoelectric element unit 11 includes piezoelectric elements 11a, 11b, 11c, and 11d having the same shape as the piezoelectric elements 1a to 1d. The piezoelectric elements 11 a to 11 d are bonded so that their long sides are directed in the radial direction from the center of the piezoelectric thin film vibrator 6. The piezoelectric elements 1a, 1b, 1c, and 1d and the piezoelectric elements 11a, 11b, 11c, and 11d are circumferentially arranged in this order.

  Between the piezoelectric elements adjacent to the piezoelectric elements 1a to 1d, a substantially fan-shaped space portion 17 that electrically insulates the piezoelectric elements from each other is formed. An angle θ1 formed by a virtual straight line that extends in the radial direction from the center of the piezoelectric thin film vibrator 6 (the center of the outer circumference circle 6a in FIG. 2) and bisects the piezoelectric element 1a and a virtual straight line that bisects the piezoelectric element 1b. Is approximately π / 5 (rad). Similarly, an angle θ2 formed by a virtual straight line that bisects the piezoelectric element 1b and a virtual straight line that bisects the piezoelectric element 1c is approximately π / 5. In addition, an angle θ3 formed by a virtual straight line that bisects the piezoelectric element 1c and a virtual straight line that bisects the piezoelectric element 1d is approximately π / 5.

  Between the piezoelectric elements adjacent to the piezoelectric elements 11a to 11d, a substantially fan-shaped space 17 that insulates the piezoelectric elements from each other is formed. An angle θ5 formed by a virtual straight line that extends in the radial direction from the center of the piezoelectric thin film vibrator 6 (the center of the outer circumference circle 6a in FIG. 2) and bisects the piezoelectric element 11a and a virtual straight line that bisects the piezoelectric element 11b. Is approximately π / 5 (rad). Similarly, an angle θ6 formed by a virtual straight line that bisects the piezoelectric element 11b and a virtual straight line that bisects the piezoelectric element 11c is approximately π / 5. In addition, an angle θ7 formed by a virtual straight line that bisects the piezoelectric element 11c and a virtual straight line that bisects the piezoelectric element 11d is approximately π / 5. That is, the interval between the bonding positions of the piezoelectric elements 1a to 1d and 11a to 11d is equal in the two piezoelectric element portions 1 and 11.

  An angle θ4 formed by a virtual straight line that bisects the piezoelectric element 1d and a virtual straight line that bisects the piezoelectric element 11a is approximately π / 2 (rad). That is, the angle θ4 is approximately 2.5 times the angle θ1. An angle θ8 formed by a virtual straight line that bisects the piezoelectric element 11d and a virtual straight line that bisects the piezoelectric element 1a is approximately 3π / 10 (rad). That is, the angle θ8 is approximately 1.5 times the angle θ1.

  On the resonator 4, arc-shaped connection electrodes 53a, 53b, 53c and 53d, an annular connection electrode 54, electrode terminals 55a, 55b, 55c and 55d, and an electrode terminal 57 are formed. The electrode terminals 55a, 55b, 55c, 55d and the electrode terminal 57 are formed in the gap between the piezoelectric element 1d and the piezoelectric element 11a. The connection electrode 53a is formed in the vicinity of the through hole 5 and the piezoelectric element portion 1 and is electrically connected to the electrode terminal 55a. The connection electrode 53a has a protrusion that overlaps the piezoelectric elements 1a and 1c when viewed in the direction perpendicular to the surface of the resonator 4 plate. The connection electrode 53b is formed in the vicinity of the outer circumference circle 6a and the piezoelectric element portion 1, and is electrically connected to the electrode terminal 55b. Further, the connection electrode 53b has a protrusion that overlaps the piezoelectric elements 1b and 1d when viewed in a direction perpendicular to the plate surface of the resonator 4.

  The connection electrode 53c is formed in the vicinity of the through hole 5 and the piezoelectric element portion 11, and is electrically connected to the electrode terminal 55c. Further, the connection electrode 53c has a protrusion that overlaps the piezoelectric elements 11b and 11d when viewed in the direction perpendicular to the surface of the resonator 4 plate. The connection electrode 53d is formed in the vicinity of the outer circumference circle 6a and the piezoelectric element portion 11, and is electrically connected to the electrode terminal 55d. Further, the connection electrode 53d has a protrusion that overlaps the piezoelectric elements 11a and 11c when viewed in the direction perpendicular to the surface of the resonator 4 plate. The connection electrode 54 intersects with the central part of each of the piezoelectric elements 1 a to 1 d and 11 a to 11 d when viewed in the direction perpendicular to the plate surface of the resonator 4 and is electrically connected to the electrode terminal 57. The electrode terminal 57 is connected to the ground.

  As shown in FIG. 3, the piezoelectric elements 1 a to 1 d and 11 a to 11 d are composed of a first electrode 3 that is an epitaxial film and, for example, lead zirconate titanate formed on the first electrode 3. A piezoelectric thin film 2 that is an epitaxial film and a second electrode 13 formed on the piezoelectric thin film 2 are provided. In the piezoelectric elements 1a to 1d and 11a to 11d, the side walls and the surface of the second electrode 13 are covered with a polyimide film 72, and the surface 3s of the first electrode 3 is covered with an oxide film (not shown).

  Holes 25 reaching the surface of the second electrode 13 from the polyimide film 72 are opened at the ends of the piezoelectric elements 1a to 1d and 11a to 11d, and from the polyimide film 72 to the surface of the first electrode 3 at the center. The reaching hole 35 is opened. The inner wall surface of the hole 35 is covered with a polyimide film 72. The hole 25 and the hole 35 are filled with Au, and a via hole 77 and a via hole 78 are formed. Since the inner wall surface of the hole 35 is covered with the polyimide film 72, the first electrode 3 and the second electrode 13 are electrically insulated. An electrode pad 63 and an electrode pad 64 are formed at the tips of the via hole 77 and the via hole 78.

  The piezoelectric elements 1 a to 1 d and 11 a to 11 d have the second electrode 13 side (the surface on which the electrode pad 63 and the electrode pad 64 are formed) opposed to the resonator 4, and are bonded to the resonator 4 by the adhesive layer 40. As shown in FIG. 3, a hole 45 is formed at the end of the adhesive layer 40 that overlaps the electrode pad 63, and a hole 65 is formed at the center that overlaps the electrode pad 64.

  The second electrode 13 of the piezoelectric elements 1a and 1c is electrically connected to the connection electrode 53a via the via hole 77 and the electrode pad 63 (FIG. 3 shows only the piezoelectric element 1c). Similarly, the second electrode 13 of the piezoelectric elements 1b and 1d is electrically connected to the connection electrode 53b via the via hole 77 and the electrode pad 63.

  The second electrodes 13 of the piezoelectric elements 11 a and 11 c are electrically connected to the connection electrode 53 d through the via hole 77 and the electrode pad 63. Similarly, the second electrode 13 of the piezoelectric elements 11b and 11d is electrically connected to the connection electrode 53c through the via hole 77 and the electrode pad 63. The first electrodes 3 of the piezoelectric elements 1 a to 1 d and 11 a to 11 d are electrically connected to the connection electrode 54 through the via holes 78 and the electrode pads 64.

  Next, the operation of the piezoelectric thin film vibrator 6 according to the present embodiment will be described with reference to FIG. FIG. 4 is a diagram schematically showing a cross section taken along line BB in FIG. As shown in FIG. 4, the polarization directions of the piezoelectric thin films 2a to 2d of the piezoelectric elements 1a to 1d bonded to the resonator 4 are the same, and the direction is the normal direction of the substrate surface of the piezoelectric thin film vibrator 6 (FIG. 4). 4, the polarization direction is schematically shown by a plurality of arrows with the tip of the arrow pointing upward). Although not shown in FIG. 4, the polarization directions of the piezoelectric thin films 2 of the piezoelectric elements 11 a to 11 d are aligned with the polarization directions of the piezoelectric thin films 2 a to 2 d.

  When the first electrode 3 is maintained at the ground potential and a positive voltage (indicated by “+” in FIG. 4) is applied to the second electrodes 13 of the piezoelectric elements 1a and 1c, In the piezoelectric thin films 2a and 2c between the two electrodes 13, a compressive force is generated as shown by two arrows in FIG. As a result, the vicinity of the piezoelectric thin films 2a and 2c of the resonator 4 warps in a convex shape downward in FIG. On the other hand, when a negative voltage (indicated by "-" in FIG. 4) is applied to the second electrode 13 of the piezoelectric elements 1b and 1d, the piezoelectric thin film 2b between the first electrode 3 and the second electrode 13 is applied. In 2d, an extension force is generated as shown by two arrows in which the tip of the arrow points in the opposite direction in FIG. Accordingly, the vicinity of the piezoelectric thin films 2b and 2d of the resonator 4 is warped in a convex shape upward in FIG.

  Conversely, when a negative voltage is applied to the second electrode 13 of the piezoelectric elements 1a and 1c, a tensile force is generated in the piezoelectric thin films 2a and 2c formed between the first electrode 3 and the second electrode 13. . As a result, the vicinity of the piezoelectric thin films 2a and 2c of the resonator 4 warps in a convex shape upward in FIG. When a positive voltage is applied to the second electrode 13 of the piezoelectric elements 1b and 1d, compressive force is generated in the piezoelectric thin films 2b and 2d formed between the first electrode 3 and the second electrode 13. . As a result, the vicinity of the piezoelectric thin films 2b and 2d of the resonator 4 warps in a convex shape downward in FIG.

  The piezoelectric elements 1a, 1b, 1c, and 1d of the resonator 4 are applied to the piezoelectric elements 1a to 1d arranged in the radial direction by applying voltages having opposite polarities to the piezoelectric elements 1a and 1c and the piezoelectric elements 1b and 1d as described above. Concave and convex deflection occurs in the region corresponding to.

  AC voltage V1 = Asin (ωt) (V) (where A is the maximum amplitude, ω is the angular frequency, and t is time) having an effective value of 3.3 V is applied to the piezoelectric elements 1a and 1c, When an alternating voltage V2 = Asin (ωt + π) (V) is applied to 1d, a flexural vibration in which an extension force and a compression force are repeated at a frequency f1 = ω / 2π (Hz) is generated in the piezoelectric thin films 2a and 2c. On the other hand, in the piezoelectric thin films 2b and 2d, a flexural vibration having a phase shifted by π (half cycle) at the same frequency f1 as the flexural vibration in the piezoelectric thin films 2a and 2c is generated.

  These flexural vibrations propagate through the resonator 4 and become standing waves that vibrate in the direction normal to the substrate surface of the piezoelectric thin film vibrator 6 at a frequency f1 = ω / 2π (Hz). At this time, the wavelength of the standing wave in the outer circumference circle 6a of the piezoelectric thin film vibrator 6 is 1/5 of the length of the outer circumference circle 6a.

  On the other hand, an AC voltage V3 = Asin {ωt− (π / 2)} (V) having an effective value of 3.3 V is applied to the piezoelectric elements 11a and 11c, and V4 = Asin {ωt + (π / 2) is applied to the piezoelectric elements 11b and 11d. )} When (V) is applied, the piezoelectric thin film 2 of the piezoelectric elements 11a to 11d has a flexural vibration repeated at a frequency f1 = ω / 2π (Hz) and a phase shifted by π at the same frequency f1 as the flexural vibration. Deflection vibration occurs.

  These flexural vibrations propagate through the resonator 4 and become standing waves that vibrate in the direction normal to the substrate surface of the piezoelectric thin film vibrator 6 at a frequency f1 = ω / 2π (Hz). At this time, the wavelength of the standing wave in the outer circumference circle 6a of the piezoelectric thin film vibrator 6 is 1/5 of the length of the outer circumference circle 6a.

  The phase of the standing wave generated by the AC voltage applied to the piezoelectric element unit 1 is different from the phase of the standing wave generated by the AC voltage applied to the piezoelectric element unit 11 by π / 2. A bending traveling wave is generated in the entire piezoelectric thin film vibrator 6 by the interference of two standing waves having a phase difference of π / 2. The traveling direction of the bending traveling wave is the circumferential direction of the piezoelectric vibrator 6 (the direction perpendicular to the radial direction of the outer circumferential circle 6a in FIG. 2).

  Next, a method for manufacturing the piezoelectric thin film vibrator 6 according to the present embodiment will be described with reference to FIGS.

  For the production of the piezoelectric thin film vibrator 6, it is preferable to use the vapor deposition method and the sputtering method described below. First, the Si single crystal substrate 14 is set in a holder of a vapor deposition apparatus (not shown) so that the (100) plane is exposed (see FIG. 5A). Here, it is preferable that the substrate surface 14a is etched and cleaned using a mirror-finished wafer. Specifically, etching cleaning is performed with a 40% ammonium fluoride aqueous solution or the like. Further, since the cleaned Si single crystal substrate 14 is extremely reactive, it is preferable to protect it from contamination by performing a predetermined surface treatment.

Next, an oxide film is formed on the substrate surface 14a of the Si single crystal substrate 14 by epitaxial growth of a 0.01 μm thick ZrO ₂ film and a 0.04 μm thick Y ₂ O ₃ film sequentially by vapor deposition ( (Not shown in FIG. 5). Here, the ZrO ₂ film is an epitaxial film made of zirconium oxide (ZrO ₂ ), and the Y ₂ O ₃ film is an epitaxial film made of yttrium oxide (Y ₂ O ₃ ). More specifically, Zr is supplied from the Zr evaporation section to the surface 14a of the Si single crystal substrate 14 heated to 400 ° C. or higher in an oxygen atmosphere obtained by a gas supply device to form a 0.01 μm thick ZrO film. _Two films are epitaxially grown, and then Y is supplied from the Y evaporation section to epitaxially grow a 0.04 μm thick Y ₂ O ₃ film. The film surface of the ZrO ₂ film epitaxially grown in this way becomes the (001) plane, and the film surface of the Y ₂ O ₃ film becomes the (100) plane.

In the case of forming a film on a large single crystal substrate surface having a substrate area of 10 cm ² or more, for example, 2 inches in diameter, Si gas is supplied to the vicinity of the substrate using a gas supply device having a plurality of outlets. By rotating the single crystal substrate 14 with a motor, a high oxygen partial pressure can be supplied to the entire surface of the substrate, and a uniform film can be formed over a large area. At this time, the number of rotations of the substrate is desirably 10 rpm or more. This is because if the rotation speed is slow, a film thickness distribution occurs in the substrate surface. Although there is no upper limit on the number of rotations of the substrate, it is usually about 120 rpm because of the mechanism of the vacuum apparatus.

Next, a metal thin film having a thickness of 0.1 to 0.3 μm is epitaxially grown on the Y ₂ O ₃ film to form a first metal thin film 23 (see FIG. 5B). More specifically, Pt is supplied from the Pt evaporation section to the upper surface of the Si single crystal substrate 14 on which the Y ₂ O ₃ epitaxial film is formed in an oxygen plasma environment, and the thickness of Pt is 0. A metal thin film having a thickness of 0.1 to 0.1 μm is epitaxially grown by vapor deposition, and a metal thin film having a thickness of 0.1 to 0.2 μm composed of Pt is further epitaxially grown thereon by using a sputtering method. The metal thin film 23 is formed. The Pt metal thin film 23 epitaxially grown in this way is oriented in the <100> direction.

  Next, a PLT film having a thickness of 0.02 μm and a PZT film having a thickness of 2.5 μm are sequentially epitaxially grown on the first metal thin film 23 using a sputtering method to form a piezoelectric thin film 22 (FIG. 5 ( c)). Here, the PLT film is an epitaxial film composed of lead titanate (PLT) doped with La, and the PZT film is an epitaxial film composed of lead zirconate titanate (PZT). Both of these PLT films and PZT films have a perovskite crystal structure, and the growth direction (thickness direction) is a c-plane unidirectional epitaxial film with a <001> direction or a <001> direction. The domain of <001> direction is a dominant film with an epitaxial film having a domain structure in which the domain of <100> and the domain of <100> are mixed.

Next, a second metal thin film 33 having a thickness of 0.2 μm is formed on the piezoelectric thin film 22 by sputtering (see FIG. 5D). Through the above steps, the piezoelectric element layer 101 in which the first metal thin film 23, the piezoelectric thin film 22, and the second metal thin film 33 are laminated in this order is formed. The orientation relationship of the epitaxial film of PZT / PLT / Pt / Y ₂ O ₃ / ZrO ₂ / Si structure formed in this way is, for example, the direction perpendicular to the film surface when both PZT and PLT are c-plane single orientations. PZT <001> / PLT <001> / Pt <100> / Y2O3 <100> / ZrO2 <001> / Si <100> and PZT <100> // PLT <100> // in the in-plane direction Pt <100> // Y2O3 <100> // ZrO2 <100> // Si <100>. When PZT or PLT has a domain structure, a <100> portion of PZT and PLT is replaced with <001>, and a <001> portion is replaced with <100>.

  Next, the piezoelectric element layer 101 is patterned into a rectangular shape having a long side of 10 mm and a short side of 1 mm using a photolithography method to form a plurality of stacked bodies 111 (see FIG. 5E). More specifically, a positive photoresist is applied on the entire surface of the second metal thin film 33 to form a resist layer (not shown). Next, the resist layer is patterned to form a resist pattern. Using the resist pattern as an etching mask, the second metal thin film 33, the piezoelectric thin film 22, and the first metal thin film 23 are etched, and the second electrode 13 and the piezoelectric film are etched. A plurality of stacked bodies 111 each having the element 2 and the first electrode 3 are formed. By this patterning, an outer edge of a piezoelectric element described later is determined. In addition to this patterning, a hole 35 exposing the surface of the first electrode 3 is formed in the central portion of each stacked body 111 separated by patterning.

  Next, polyimide is applied over the entire surface of the Si single crystal substrate 14, and the upper surface and the side wall of each stacked body 111 are integrally covered with a polyimide film (protective film) 72, and the holes of each stacked body 111 are also covered. The portion 35 is filled with polyimide (see FIG. 6A). Then, the polyimide film 72 is patterned, and the outer edge of the polyimide film 72 corresponding to each stacked body 111 is determined. At this time, the hole 25 exposing the surface of the second electrode 13 is obtained by patterning the polyimide film 72 on the end of the stacked body 111, and the polyimide film 72 in the hole 35 is slightly smaller than the hole 35. By etching away with the dimensions, the hole 35 whose inner wall surface is covered with the polyimide film 72 is obtained (see FIG. 6B).

  Subsequently, in each stacked body 111, the hole 25 where the inner wall surface is exposed and the hole 35 where the inner wall surface is covered with the polyimide film 72 are filled with Au to form two via holes 77 and 78 ( (Refer FIG.6 (c)). That is, the via hole 77 extends to the second electrode 13, and the via hole 78 extends to the first electrode 3. Since the inner wall surface of the via hole 78 is covered with the polyimide film 72, the first electrode 3 and the second electrode 13 are electrically insulated. Further, the electrode pad 63 is formed at the tip of the via hole 77 and the electrode pad 64 is formed at the tip of the via hole 78 by the same process.

  Next, the Si single crystal substrate 14 is removed with an alkaline solution such as potassium hydroxide, or an etchant such as hydrofluoric acid or hydrofluoric acid (see FIG. 6D). Thereby, the plurality of stacked bodies 111 are separated from the Si single crystal substrate 14, the surface and side walls of the second electrode 13 are covered with the polyimide film 72, and the surface 3s of the first electrode 3 is covered with an oxide film (not shown). A plurality of broken piezoelectric elements are obtained (only the piezoelectric element 1c is shown in FIG. 6D).

  Next, the electrode pad 63 and the electrode pad 64 forming surfaces of the piezoelectric elements 1a to 1d and 11a to 11d are sandwiched with a thermoplastic film type adhesive (for example, STAYSTIK (manufactured by Techno Alpha)) 140, for example, polyethylene terephthalate, etc. It is made to contact with the resonator 4 formed of the synthetic resin. (See FIG. 7A. In FIG. 7A, only the right half of FIG. 3 is shown.)

  A hole 45 and a hole 65 are formed in the electrode pad 63 and the portion of the adhesive 140 that overlaps the electrode pad 64. On the resonator 4, the connection electrodes 53a to 53d and the connection electrode 54 are formed in advance by, for example, photolithography, and the electrode pad 63 and the electrode pad 64 are connected to the connection electrodes 53a to 53d through the hole 45 and the hole 65, respectively. And contact the connection electrode 54. In order to electrically connect the electrode pad 63 and the electrode pad 64 with the connection electrodes 53a to 53d and the connection electrode 54, a silver paste or the like is applied in the vicinity of the hole 45 and the hole 65 of the adhesive 140. Good. When the adhesive 140 is heated on a hot plate at 130 ° C. for 5 minutes in this state, the adhesive 140 is cured to become the plastic adhesive layer 40, and the piezoelectric elements 1 a to 1 d and 11 a to 11 d are transferred to the resonator 4 via the adhesive layer 40. They are pasted together (see FIG. 7B).

  Next, the center portion of the resonator 4 is ground by a sand blast method or a photolithography method to form the through hole 5. As described above, the manufacture of the piezoelectric thin film vibrator 6 in which the plurality of piezoelectric elements 1 a to 1 d and 11 a to 11 d are bonded to the resonator 4 through the adhesive layer 40 is completed.

  In the piezoelectric thin film vibrator 6 according to the present embodiment, a plurality of rectangular piezoelectric elements are formed on a Si single crystal substrate 14 which is a substrate different from the resonator 4. Since a plurality of piezoelectric elements can be densely formed on the Si single crystal substrate 14, the number of piezoelectric elements from one Si single crystal substrate 14 increases, and the piezoelectric elements can be manufactured at low cost. it can.

  In addition, the piezoelectric elements 1a to 1d and 11a to 11d are bonded to the resonator 4 only in a necessary number to function as the piezoelectric thin film vibrator 6. Since it is not necessary to form a metal thin film, a piezoelectric thin film or the like in an unnecessary portion, the piezoelectric thin film vibrator 6 can be manufactured at a low cost. In addition, since an inexpensive synthetic resin such as polyethylene terephthalate is used as the resonator 4, the piezoelectric thin film vibrator 6 can be manufactured at a lower cost. Furthermore, since the Si single crystal substrate 14 and the resonator 4 are different substrates, the material of the resonator 4 can be selected from various materials, so that the degree of freedom in designing the deflection amount and the deflection frequency of the piezoelectric thin film vibrator 6 is expanded. In the case of a rotating operation, the speed can be increased.

  Further, the crystal orientation of the thin film formed by epitaxial growth is aligned with the orientation having a specific relationship with the crystal orientation of the base. The first electrode 3 is formed by epitaxial growth on the (100) plane of the surface of the Si single crystal substrate 14. The first electrode 3 is oriented in the <100> direction. A piezoelectric thin film 2 is formed on the first electrode 3 by epitaxial growth. The piezoelectric thin film 2 is preferentially oriented in the <001> direction. Therefore, since the polarization directions of the piezoelectric thin films 2 of the plurality of piezoelectric elements formed on the Si single crystal substrate 14 are aligned in a predetermined direction, the piezoelectric thin film 2 with good piezoelectric characteristics can be obtained and no polarization treatment is required. Therefore, the manufacturing process of the piezoelectric element is simplified, and a piezoelectric element having good piezoelectric characteristics can be obtained at low cost.

  In addition, the same surface of the plurality of manufactured piezoelectric elements is bonded to the resonator 4. Therefore, the polarization directions of the piezoelectric thin films 2 of the piezoelectric elements 1a to 1d and 11a to 11d bonded to the resonator 4 are aligned with the normal direction of the substrate surface of the piezoelectric thin film vibrator 6 (in FIG. Tip is schematically shown by a plurality of arrows pointing up).

  In the above-described piezoelectric thin film vibrator 6 according to the present embodiment, the single-layer piezoelectric elements 1a to 1d and 11a to 11d are used, but instead of the single-layer piezoelectric elements 1a to 1d and 11a to 11d, FIG. As shown in FIG. 8B, piezoelectric elements 20 and 30 in which a single-layer piezoelectric element 10 is bonded to each other through an adhesive 80 to form two layers may be used. By using the two-layer piezoelectric elements 20 and 30, the torque of the rotational motion generated by the bending traveling wave, which will be described later, is almost doubled, and the effect of amplifying the amplitude of the bending traveling wave is obtained.

  As shown in FIG. 8 (a), in the two-layer piezoelectric element 20, the polarization direction of the piezoelectric thin film 2 of the two single-layer piezoelectric elements 10 is opposite (in FIG. The surfaces of the second electrodes 13 are bonded to each other with an adhesive 80 so as to be schematically shown by arrows. When the two-layer piezoelectric element 20 is used for the piezoelectric thin film vibrator 6, the two first electrodes 3 formed on the outside are maintained at the ground potential as schematically shown by “-” in FIG. A predetermined AC voltage is applied from the AC power supply unit 51 to the two second electrodes 13 formed on the inner side as schematically indicated by “+” in FIG.

  When the two piezoelectric elements 10 are bonded so that the polarization directions are opposite to each other, the stress acting in the direction perpendicular to the film surface of one piezoelectric element 10 and the direction perpendicular to the film surface of the other piezoelectric element 10 are exerted. Since the stress is canceled out, the effect of eliminating the warp of the piezoelectric element 20 is obtained. Therefore, it becomes easy to bond the piezoelectric element 20 to the resonator 4.

  The manufacturing method of the piezoelectric element 20 in which the polarization directions of the two piezoelectric thin films 2 are opposite to each other is the same as the manufacturing method of the single-layer piezoelectric element described above up to the step of forming the piezoelectric element layer 101 (FIG. 5D). It is this process. After forming the piezoelectric element layer 101 on each of the two Si single crystal substrates 14 as described above, the surfaces of the second metal thin films 33 of the two Si single crystal substrates 14 are bonded to each other with an adhesive 80, and the piezoelectric elements are bonded. The layer 101 is laminated, one of the two Si single crystal substrates 14 is ground and removed, the laminated piezoelectric element layer 101 is patterned into a predetermined shape, and the other of the two Si single crystal substrates 14 is ground. A plurality of two-layer piezoelectric elements 20 are formed by removal.

  As shown in FIG. 8B, in the two-layer piezoelectric element 30, the polarization directions of the piezoelectric thin film 2 of the two single-layer piezoelectric elements 10 are in the same direction (in FIG. 8B, the tips are in the same direction). The surface of the first electrode 3 of one piezoelectric element 10 and the surface of the second electrode 13 of the other piezoelectric element 10 are bonded via an adhesive 80 so as to be schematically shown by two arrows). . When the two-layer piezoelectric element 30 is used for the piezoelectric thin film vibrator 6, the two first electrodes 3 are maintained at the ground potential as schematically shown by “−” in FIG. A predetermined AC voltage is applied to the electrode 13 from the AC power source 51 as schematically indicated by “+” in FIG.

  Next, the driving apparatus according to the present embodiment will be described with reference to FIG. FIG. 9 shows the configuration of the driving apparatus according to this embodiment. As shown in FIG. 9, the drive device according to the present embodiment includes a piezoelectric thin film vibrator 6 and an AC power supply unit 51. The AC power supply unit 51 includes AC power supplies 51a, 51b, 51c, and 51d.

  The AC power source 51a is electrically connected to the second electrode 13 of the piezoelectric elements 1a and 1c through the electrode terminal 55a. The AC power supply 51b is electrically connected to the second electrode 13 of the piezoelectric elements 1b and 1d via the electrode terminal 55b. The AC power source 51d is electrically connected to the second electrodes 13 of the piezoelectric elements 11a and 11c through the electrode terminal 55d. The AC power supply 51c is electrically connected to the second electrodes 13 of the piezoelectric elements 11b and 11d through the electrode terminal 55c.

  The drive device according to the present embodiment is not only used in a piezoelectric motor described later, but also a detachable rotary recording medium is attached to the piezoelectric thin film vibrator 6 via a liquid or gas (for example, air) fluid, A driving force for rotating the medium in a non-contact manner can also be applied. The fluid moves in the direction opposite to the traveling direction of the bending traveling wave, and the media rotates following the rotational movement direction of the fluid.

  Next, the piezoelectric motor according to the present embodiment will be described with reference to FIG. FIG. 10 is a perspective view showing the configuration of the piezoelectric motor according to the present embodiment. As shown in FIG. 10, the piezoelectric motor according to the present embodiment includes a stator provided with the driving device according to the present embodiment (only the piezoelectric thin film vibrator 6 is shown in FIG. 10), and a piezoelectric thin film vibrator 6 on the stator. The rotor 7 is disposed.

  The rotor 7 is formed in a thin plate shape and has a circular outer periphery. A circular through hole 15 whose center is substantially coincident with the outer peripheral circle 7 a of the rotor 7 is formed in the center of the rotor 7. A cylindrical shaft (shaft) (not shown) passes through the through hole 5 and the through hole 15, and the rotational axis of the rotor 7 substantially coincides with the central axis of the piezoelectric thin film vibrator 6 (indicated by a one-dot chain line in the figure). ing). In the piezoelectric motor according to the present embodiment, the piezoelectric element portion 1 forming surface of the piezoelectric thin film vibrator 6 faces the rotor 7, but the resonator 4 forming surface may face the rotor 7.

  As described above, when two standing waves having different phases by π / 2 (rad) interfere with each other, a bending traveling wave is generated in the entire piezoelectric thin film vibrator 6. The traveling direction of the bending traveling wave is the circumferential direction of the piezoelectric vibrator 6 (in FIG. 10, the direction orthogonal to the radial direction of the outer circumferential circle 6a in the substrate surface). When the piezoelectric thin film vibrator 6 and the rotor 7 are pressed against each other, the rotor 7 rotates in a direction opposite to the traveling direction of the bending traveling wave generated in the piezoelectric thin film vibrator 6 due to friction.

[Second Embodiment]
A piezoelectric thin film vibrator according to a second embodiment of the present invention will be described with reference to FIG. FIG. 11 is a cross-sectional view showing the configuration of the piezoelectric thin film vibrator 16 according to the present embodiment. In the following description of the piezoelectric thin film vibrator and the like, components having the same functions and operations as those of the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.

  In the piezoelectric thin film vibrator 16 according to the present embodiment, piezoelectric elements are bonded to the front and back surfaces of the resonator 4. Similarly to the first embodiment, the piezoelectric elements 1a to 1d and 11a to 11d are bonded to the surface of the resonator 4 via the adhesive layer 40, and the connection electrodes 53a to 53d and 54 and the electrode terminals 55a to 55d and 57 are bonded. Is formed. The piezoelectric elements 21a to 21d and the piezoelectric elements 31a to 31d are respectively bonded to the back surface of the resonator 4 through the adhesive layer 40 immediately below the piezoelectric elements 1a to 1d and 11a to 11d bonded to the front surface (see FIG. 11 shows only the piezoelectric element 21c and the piezoelectric element 31b).

  In the piezoelectric elements 21 a to 21 d and the piezoelectric elements 31 a to 31 d bonded to the back surface, the second electrode 13 side (electrode pad 63 and electrode pad 64 formation surface) faces the resonator 4. Therefore, the polarization direction of the piezoelectric thin film 2 of the piezoelectric elements 1a to 1d and 11a to 11d formed on the front surface and the polarization direction of the piezoelectric thin film 2 of the piezoelectric elements 21a to 21d and the piezoelectric elements 31a to 31d formed on the back surface thereof. It is in the opposite direction.

  On the back surface of the resonator 4, connection electrodes 73 a to 73 d and a connection electrode 74 having substantially the same shape as the connection electrodes 53 a to 53 d and the connection electrode 54 are formed. The piezoelectric elements 21a to 21d and the second electrodes 13 of the piezoelectric elements 31a to 31d are electrically connected to the connection electrodes 73a to 73d via the electrode pads 63, and the first electrode 3 is connected via the electrode pads 64. It is electrically connected to the electrode 74.

  The same AC voltage V2 = Asin (ωt + π) (V) as that applied to the piezoelectric elements 1b and 1d is applied to the piezoelectric elements 21a and 21c, and applied to the piezoelectric elements 1a and 1c to the piezoelectric elements 21b and 21d. The same AC voltage V1 = Asin (ωt) (V) is applied. Further, the same AC voltage V4 = Asin {ωt + (π / 2)} (V) as that applied to the piezoelectric elements 11b and 11d is applied to the piezoelectric elements 31a and 31c, and the piezoelectric elements 31b and 31d are piezoelectric. The same AC voltage V3 = Asin {ωt− (π / 2)} (V) as that applied to the elements 11a and 11c is applied. That is, an AC voltage whose phase is shifted by a half cycle is applied to the piezoelectric elements 1a to 1d and 11a to 11d formed on the front surface and the piezoelectric elements 21a to 21d and piezoelectric elements 31a to 31d formed on the rear surface. .

  As a result, when compressive force is generated in the piezoelectric elements 1a to 1d and 11a to 11d formed on the surface, tensile force is generated in the piezoelectric elements 21a to 21d and the piezoelectric elements 31a to 31d formed immediately below the piezoelectric elements. In the piezoelectric thin film vibrator 16 according to the present embodiment, the rotational motion torque generated by the bending traveling wave is doubled as compared with the piezoelectric thin film vibrator 6 according to the first embodiment, and the amplitude of the bending traveling wave is also increased. The effect of almost doubling is obtained.

[Third Embodiment]
A piezoelectric thin film vibrator 26 according to a third embodiment of the present invention will be described with reference to FIGS. FIG. 12 is a plan view showing the configuration of the piezoelectric thin film vibrator 26 according to the present embodiment. FIG. 13 is a cross-sectional view taken along line AA in FIG.

  As shown in FIG. 12, piezoelectric element portions 41 and 61 are formed on the resonator 4. The piezoelectric element unit 41 has the same function as the piezoelectric element unit 1 of FIG. 2, and the piezoelectric element unit 61 has the same function as the piezoelectric element unit 11 of FIG. The piezoelectric element unit 41 includes piezoelectric elements 41a, 41b, 41c, and 41d having the same shape as the piezoelectric elements 1a to 1d. Similarly, the piezoelectric element portion 61 includes piezoelectric elements 61a, 61b, 61c, and 61d having the same shape as the piezoelectric elements 41a to 41d. The piezoelectric elements 41a, 41b, 41c, 41d and the piezoelectric elements 61a, 61b, 61c, 61d are circumferentially arranged in this order.

  As shown in FIG. 13, the piezoelectric element 41 a is bonded to the surface of the resonator 4 via the adhesive layer 40, and the piezoelectric element 41 b adjacent to the piezoelectric element 41 a is bonded to the back surface of the resonator 4 via the adhesive layer 40. . The piezoelectric element 41 c adjacent to the piezoelectric element 41 b is bonded to the surface of the resonator 4 via the adhesive layer 40, and the piezoelectric element 41 d adjacent to the piezoelectric element 41 c is bonded to the back surface of the resonator 4 via the adhesive layer 40. Yes.

  Similarly, the piezoelectric element 61 a is bonded to the back surface of the resonator 4 via the adhesive layer 40, and the piezoelectric element 61 b adjacent to the piezoelectric element 61 a is bonded to the surface of the resonator 4 via the adhesive layer 40. The piezoelectric element 61c adjacent to the piezoelectric element 61b is bonded to the back surface of the resonator 4 via the adhesive layer 40, and the piezoelectric element 61d adjacent to the piezoelectric element 61c is bonded to the surface of the resonator 4 via the adhesive layer 40. Yes.

  As shown in FIG. 13, the piezoelectric elements 41a to 41d and the piezoelectric elements 61a to 61d are all bonded so that the surface on which the second electrode 13 is formed faces the resonator 4 (the piezoelectric elements 61a to 61d are not shown in FIG. 13). (Illustrated). Therefore, the polarization directions of the piezoelectric thin films 2 of the piezoelectric elements 41a and 41c and the piezoelectric elements 61b and 61d bonded to the surface of the resonator 4 are the same as the piezoelectric thin films 2 of the piezoelectric elements 41b and 41d and the piezoelectric elements 61a and 61c bonded to the back surface. Is the opposite direction of the polarization direction (schematically shown by arrows pointing in the vertical direction in the figure).

  Similar to the first embodiment, connection electrodes 53a and 53c, a connection electrode 54, and electrode terminals 55a, 55c and 57 are formed on the surface of the resonator 4. On the back surface of the resonator 4, connection electrodes 83 b and 83 d having substantially the same shape as the connection electrodes 53 a and 53 c are formed, and a connection electrode 84 having substantially the same shape as the connection electrode 54 is formed. The connection electrode 83b is electrically connected to the connection electrode 53a, and the connection electrode 83d is electrically connected to the connection electrode 53c. The connection electrode 84 is connected to the ground.

  The second electrodes 13 of the piezoelectric elements 41b and 41d formed on the back surface are electrically connected to the connection electrode 83b. The second electrodes 13 of the piezoelectric elements 61a and 61c formed on the back surface are electrically connected to the connection electrode 83d. The first electrodes 3 of the piezoelectric elements 41 b and 41 d and the piezoelectric elements 61 a and 61 c are electrically connected to the connection electrode 84.

  When the first electrode 3 is maintained at the ground potential and a positive voltage (indicated by “+” in FIG. 13) is applied to the second electrodes 13 of the piezoelectric elements 41a to 41d, the piezoelectric elements 41a to 41d have piezoelectricity. In the thin film 2, a compressive force is generated as shown by two arrows in which the tip of the arrow faces in FIG. Accordingly, the resonator 4 in the vicinity of the piezoelectric elements 41a and 41c warps in a convex shape downward in FIG. 13, and the resonator 4 in the vicinity of the piezoelectric elements 41b and 41d warps in a convex shape upward in FIG. On the other hand, when a negative voltage is applied to the second electrodes 13 of the piezoelectric elements 41a to 41d, stretching force is generated in the piezoelectric thin film 2 of the piezoelectric elements 41a to 41d. Accordingly, the resonator 4 in the vicinity of the piezoelectric elements 41a and 41c warps in a convex shape upward in FIG. 13, and the resonator 4 in the vicinity of the piezoelectric elements 41b and 41d warps in a convex shape downward in FIG.

  Similarly, when a positive voltage is applied to the second electrode 13 of the piezoelectric elements 61a to 61d while the first electrode 3 is maintained at the ground potential, a compressive force is applied to the piezoelectric thin film 2 of the piezoelectric elements 61a to 61d. Arise. Accordingly, the resonator 4 in the vicinity of the piezoelectric elements 61a and 61c warps in a convex shape upward in FIG. 13, and the resonator 4 in the vicinity of the piezoelectric elements 61b and 61d warps in a convex shape downward in FIG. On the other hand, when a negative voltage is applied to the second electrodes 13 of the piezoelectric elements 61a to 61d, an extension force is generated in the piezoelectric thin film 2 of the piezoelectric elements 61a to 61d. As a result, the resonator 4 near the piezoelectric elements 61a and 61c warps in a convex shape downward in FIG. 13, and the resonator 4 near the piezoelectric elements 61b and 61d warps in a convex shape upward in FIG.

  The same AC voltage V1 = Asin (ωt) (V) is applied to the piezoelectric elements 41a to 41d from the AC power supply unit 51. Similarly, the same AC voltage V3 = Asin {ωt− (π / 2)} (V) is applied to the piezoelectric elements 61a to 61d from the AC power supply unit 51. The piezoelectric thin film vibrator 26 according to the present embodiment can provide the same functions and effects as the piezoelectric thin film vibrator 6 according to the first embodiment.

[Fourth Embodiment]
A piezoelectric thin film vibrator 36 according to a fourth embodiment of the present invention will be described with reference to FIG. FIG. 14 is a plan view showing the configuration of the piezoelectric thin film vibrator 36 according to the present embodiment.

  As shown in FIG. 14, in the piezoelectric thin film vibrator 36 according to this embodiment, a resonator 24 formed of a metal such as Ni is used instead of the resonator 4 formed of synthetic resin. The resonator 24 has a thin plate shape. An annular insulating film 70a is formed on the inner peripheral portion of the resonator 24, and an annular insulating film 70b is formed on the outer peripheral portion. In the gap between the insulating film 70a and the insulating film 70b, the resonator 24 is exposed in an annular shape. The resonator 24 is connected to the ground.

  Connection electrodes 53a and 53c and electrode terminals 55a and 55c are formed on the insulating film 70a. Connection electrodes 53b and 53d and electrode terminals 55b and 55d are formed on the insulating film 70b. On the resonator 24 and the insulating films 70a and 70b, the piezoelectric elements 1a to 1d and the piezoelectric elements 11a to 11d are bonded via an adhesive layer 40 (not shown in FIG. 14). The first electrodes 3 (not shown in FIG. 14) of the piezoelectric elements 1 a to 1 d and the piezoelectric elements 11 a to 11 d are electrically connected to the resonator 24 through electrode pads 64. The second electrode 13 (not shown in FIG. 14) of the piezoelectric elements 1a and 1c is electrically connected to the connection electrode 53a via the electrode pad 63, and the second electrode 13 of the piezoelectric elements 1b and 1d is the electrode pad 63. Is electrically connected to the connection electrode 53b. The second electrodes 13 of the piezoelectric elements 11a and 11c are electrically connected to the connection electrode 53d via the electrode pad 63, and the second electrodes 13 of the piezoelectric elements 11b and 11d are connected to the connection electrode 53 via the electrode pad 63. 53c is electrically connected.

  The insulating film 70a and the insulating film 70b electrically insulate between the first electrode 3 and the second electrode 13 of the same piezoelectric elements 1a to 1d and the piezoelectric elements 11a to 11d, and adjacent piezoelectric elements (for example, piezoelectric elements) The second electrodes 13 of 1a and 1b are electrically insulated. The piezoelectric thin film vibrator 36 according to the present embodiment can provide the same functions and effects as the piezoelectric thin film vibrator 6 according to the first embodiment.

The present invention is not limited to the above embodiment, and various modifications can be made.
For example, in the above embodiment, the rectangular piezoelectric element 10 (see FIG. 15A) viewed in the direction perpendicular to the plate surface of the resonator is taken as an example. However, the present invention is not limited to this, and the resonator A fan-shaped piezoelectric element 120 (see FIG. 15B) as viewed in the direction perpendicular to the plate surface and a trapezoidal piezoelectric element 130 (see FIG. 15C) as viewed in the direction perpendicular to the plate surface of the resonator. Of course, it can also be applied when used.

  Further, in the above-described embodiment, the bending traveling wave that is rotated by the disk-shaped resonator is generated. However, the present invention is not limited to this. For example, the surface of the thin-plate rectangular resonator is discretely distributed linearly. Piezoelectric elements may be bonded together so as to line up. By doing so, it is possible to realize linear driving in which a bending traveling wave that travels linearly is generated.

  Furthermore, in the above-described embodiment, the piezoelectric thin film vibrator 6 in which the resonator 4 is formed of a synthetic resin such as polyethylene terephthalate has been described as an example. However, the present invention is not limited thereto, and the synthetic resin having a small attenuation ratio or Si Of course, the present invention can also be applied to a single crystal semiconductor substrate such as GaAs or GaAs, or a piezoelectric thin film vibrator 6 including a resonator formed of glass or ceramics.

  Furthermore, in the above embodiment, the piezoelectric thin film vibrator 6 in which Pt is used as the material of the first electrode 3 and the second electrode 13 is taken as an example. However, the present invention is not limited to this, and for example, Au, Ir , Pd, Rh, Cu and Ag may be included in the metal material group.

Further, in the above embodiment, the piezoelectric thin film 2 is an example of a thin film in which an epitaxial film made of lead zirconate titanate (PZT) is formed on an epitaxial film made of lead titanate (PLT) doped with La. Although mentioned, the present invention is not limited to this, relaxer based material typified by PMN-PT, LiNbO ₃ or KTaO _3, as a main component and barium strontium titanate, lead titanate, and ZnO or AlN wurtzite It may be an epitaxial film made of a type piezoelectric material.

  In the present embodiment, the vapor deposition method and the sputtering method are exemplified as the film formation methods of the electrodes (the first electrode 3 and the second electrode 13) and the piezoelectric thin film 2, but the film formation method is not limited thereto. Piezoelectric thin film by physical vapor deposition (evaporation method, sputtering method, MBE method, etc.), chemical vapor deposition method (MO-CVD, plasma CVD, etc.), liquid phase / solid phase growth method (sol-gel method, etc.) Since the vibrator can be manufactured, each layer can be appropriately selected from these layers and used.

As a substrate for manufacturing the piezoelectric thin film vibrator, in addition to the Si single crystal substrate 14 described in this embodiment, a semiconductor single crystal substrate such as GaAs, a single crystal substrate such as MgO, SrTiO ₃ , and sapphire, quartz And glass are available. When a single crystal substrate is used, an electrode film epitaxially grown on the substrate can be formed. Therefore, a highly crystalline piezoelectric thin film having very good electrical characteristics can be formed thereon. In addition, a polycrystalline electrode film is usually formed on a substrate such as quartz or glass, and a polycrystalline piezoelectric film having good electrical characteristics epitaxially grown thereon can be produced.

  In this specification, “epitaxial growth” means that the crystal of the target film has a specific orientation relationship both in the plane and in the direction perpendicular to the plane with respect to the crystal of the underlying film in direct contact. Represents growing. In addition, “epitaxial film” and “epitaxially grown film” indicate that the film is epitaxially grown with respect to the underlying film in direct contact with the film.

  When the piezoelectric thin film has a tetragonal perovskite structure such as PZT, a PZT film having a domain structure oriented in (001) and (100) is often obtained, but even in this case, the (001) domain and ( 100) An epitaxial film can be said to be an epitaxial film if each domain has a specific orientation relationship with the underlying crystal (such as Pt) in the in-plane and in-plane directions. This is because when PZT is formed at 600 ° C., which is higher than the Curie temperature, the PZT film changes from cubic to tetragonal during the substrate temperature drop after film formation, even if it grows epitaxially as cubic at the film formation temperature. This is because the (001) orientation domain and the (100) orientation domain are generated by the stress from the substrate.

Note that whether the film is an epitaxial film does not depend on whether the film and the base film are single crystal or polycrystalline. Moreover, it is not limited by the size of crystal grains or the size of domains. For example, when a (100) -oriented polycrystalline Pt film is produced on a Si (100) substrate whose surface is covered with a thermally oxidized SiO ₂ film, and a PZT polycrystalline film is formed thereon, If the in-plane direction of the crystal grains and the crystal orientation of the crystal grains of the PZT film formed thereon have a specific orientation relationship in both the in-plane direction and the direction perpendicular to the plane, Regardless of the size, it can be said that this PZT film is an epitaxially grown film. Further, even if the PZT film has a domain structure of (001) orientation and (100) orientation, it can be said that it is an epitaxially grown film if a specific orientation relationship with the base crystal is established for each domain.

  In the present embodiment, a thermoplastic film type is exemplified as a method for bonding a piezoelectric element to a resonator, but the bonding method is not limited to these. For example, when it is not desired to apply much heat to the resonator, the method is low. Melting point hot melt adhesive (water-based polyester resin adhesive: Aron Melt, etc.), acrylic adhesive (acrylic resin adhesive: Acrysanday, etc.), UV curable resin (UV adhesive): Chemiseal (adhesive for PET) Agent) and the like are also applicable.

1 is a perspective view showing a configuration of a piezoelectric thin film vibrator according to a first embodiment of the present invention. 1 is a plan view showing a configuration of a piezoelectric thin film vibrator according to a first embodiment of the present invention. It is sectional drawing which shows the structure of the piezoelectric thin film vibrator by the 1st Embodiment of this invention. It is sectional drawing which shows the structure of the piezoelectric thin film vibrator by the 1st Embodiment of this invention. It is a figure which shows the manufacturing method of the piezoelectric thin film vibrator by the 1st Embodiment of this invention. It is a figure which shows the manufacturing method of the piezoelectric thin film vibrator by the 1st Embodiment of this invention. It is a figure which shows the manufacturing method of the piezoelectric thin film vibrator by the 1st Embodiment of this invention. It is a figure which shows the structure of the laminated piezoelectric element. It is a top view which shows the structure of the drive device by the 1st Embodiment of this invention. It is a perspective view which shows the structure of the piezoelectric motor by the 1st Embodiment of this invention. It is a perspective view which shows the structure of the piezoelectric thin film vibrator by the 2nd Embodiment of this invention. It is a top view which shows the structure of the piezoelectric thin film vibrator by the 3rd Embodiment of this invention. It is a perspective view which shows the structure of the piezoelectric thin film vibrator by the 3rd Embodiment of this invention. It is a top view which shows the structure of the piezoelectric thin film vibrator by the 4th Embodiment of this invention. It is a figure which shows the shape of a piezoelectric element. It is a figure which shows the manufacturing method of the conventional piezoelectric thin film vibrator.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1, 11 Piezoelectric element part 1a, 1b, 1c, 1d, 10, 11a, 11b, 11c, 11d Piezoelectric element 2, 2a, 2b, 2c, 2d Piezoelectric thin film 3 1st electrode 3s 1st electrode surface 4, 24 Resonator 5, 15 Through-hole 6, 16, 26, 36 Piezoelectric thin film vibrator 6a, 26a, 36a Piezoelectric thin film vibrator outer circumference circle 7 Rotor 7a Rotor outer circumference circle 13 Second electrode 14 Si single crystal substrate 14a Si single crystal Substrate surface 17 Space part 20, 30 Two-layer piezoelectric element 22 First metal thin film 23 Second metal thin film 25, 35, 45, 65 Hole 40 Adhesive layer 51 AC power supply parts 51a, 51b, 51c, 51d AC power supply 53a, 53b, 53c, 53d, 54 Connection electrodes 55a, 55b, 55c, 55d, 57 Electrode terminals 63, 64 Electrode pads 72 Polyimide films 77, 78 Via holes 101 Piezoelectric element layer 111 laminate

Claims (20)

A resonator that generates traveling waves,
A first electrode formed by a thin film forming technique, a piezoelectric thin film formed on the first electrode, and a second electrode formed on the piezoelectric thin film are bonded to the resonator. A plurality of piezoelectric elements,
An adhesive layer for bonding each of the plurality of piezoelectric elements to the resonator. The piezoelectric thin film vibrator according to claim 1,
The piezoelectric thin film vibrator is characterized in that the piezoelectric thin film is an epitaxially grown film formed on the first electrode. The piezoelectric thin film vibrator according to claim 1 or 2,
The plurality of piezoelectric elements belong to one of two piezoelectric element portions in different arrangement regions,
The piezoelectric thin film vibrator is characterized in that an interval between bonding positions of the piezoelectric elements is equal in the two piezoelectric element portions. The piezoelectric thin film vibrator according to any one of claims 1 to 3,
The resonator has a thin plate shape,
The piezoelectric thin film vibrator according to claim 1, wherein the plurality of piezoelectric elements are bonded to a front surface and a back surface of the resonator. The piezoelectric thin film vibrator according to claim 4,
The piezoelectric thin film vibrator, wherein the piezoelectric element bonded to the back surface is bonded directly below the piezoelectric element bonded to the front surface. The piezoelectric thin film vibrator according to claim 4,
One of the two adjacent piezoelectric elements is bonded to the surface of the resonator,
The other is bonded to the back surface of the resonator. The piezoelectric thin film vibrator according to any one of claims 1 to 6,
The piezoelectric thin film vibrator has a circular outer periphery,
The piezoelectric thin film vibrator, wherein the plurality of piezoelectric elements are arranged radially. The piezoelectric thin film vibrator according to any one of claims 1 to 7,
The piezoelectric thin film vibrator according to claim 1, wherein the piezoelectric element has a rectangular shape when viewed in a direction perpendicular to a plate surface of the resonator. The piezoelectric thin film vibrator according to any one of claims 1 to 7,
The piezoelectric thin film vibrator according to claim 1, wherein the piezoelectric element has a fan shape when viewed in a direction perpendicular to the plate surface of the resonator. The piezoelectric thin film vibrator according to any one of claims 1 to 7,
The piezoelectric thin film vibrator according to claim 1, wherein the piezoelectric element has a trapezoidal shape when viewed in a direction perpendicular to the plate surface of the resonator. The piezoelectric thin film vibrator according to any one of claims 1 to 10,
The piezoelectric thin-film vibrator is characterized in that the resonator is made of metal. The piezoelectric thin film vibrator according to any one of claims 1 to 10,
The piezoelectric thin film vibrator is characterized in that the resonator is made of resin. A piezoelectric thin film vibrator according to any one of claims 1 to 12 (excluding claim 6),
An AC power supply that applies an AC voltage whose phase is shifted by a half cycle to the plurality of adjacent piezoelectric elements. A stator comprising the drive device according to claim 13;
A piezoelectric motor comprising: a rotor disposed on the piezoelectric thin film vibrator. Forming a first metal thin film on the substrate;
Forming a piezoelectric thin film on the first metal thin film;
Forming a piezoelectric element layer by forming a second metal thin film on the piezoelectric thin film;
Patterning the piezoelectric element layer into a predetermined shape;
A plurality of piezoelectric elements are formed by dividing the piezoelectric element layer into pieces,
A method of manufacturing a piezoelectric thin film vibrator, wherein the plurality of piezoelectric elements are bonded to a resonator via an adhesive layer. A method of manufacturing a piezoelectric thin film vibrator according to claim 15,
The method of manufacturing a piezoelectric thin film vibrator, wherein the piezoelectric thin film is formed by epitaxial growth on the first metal thin film. A method of manufacturing a piezoelectric thin film vibrator according to claim 15 or 16,
The plurality of piezoelectric elements are bonded to one of two different arrangement regions to form two piezoelectric element portions,
A method for manufacturing a piezoelectric thin film vibrator, comprising: bonding the piezoelectric elements at equal intervals between the two piezoelectric element portions. A method for manufacturing a piezoelectric thin film vibrator according to any one of claims 15 to 17,
A method of manufacturing a piezoelectric thin film vibrator, comprising bonding the plurality of piezoelectric elements to a front surface and a back surface of the resonator. A method of manufacturing a piezoelectric thin film vibrator according to claim 18,
A method for manufacturing a piezoelectric thin film vibrator, comprising: bonding the piezoelectric element to be bonded to the back surface directly below the piezoelectric element to be bonded to the front surface. A method of manufacturing a piezoelectric thin film vibrator according to claim 18,
Adhering one of the two adjacent piezoelectric elements to the surface of the resonator,
The other is bonded to the back surface of the resonator.

Images