JP2017117981A - Piezoelectric element, piezoelectric module, electronic device, and method of manufacturing piezoelectric element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a piezoelectric element capable of increasing a driving frequency to a high frequency, a piezoelectric module, an electronic device, and a method of manufacturing a piezoelectric element.SOLUTION: An ultrasonic transducer 20 includes: a supporting film 211, an insulating single crystal substrate 212 provided on the supporting film 211; a lower electrode 22 provided on the substrate 212; a piezoelectric body 23 provided on the lower electrode 22; and an upper electrode 24 provided on the piezoelectric body 23. A crystal plane orientation of the substrate 212 is the same as a crystal plane orientation of the piezoelectric body 23.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a piezoelectric element, a piezoelectric module, an electronic device, and a method for manufacturing a piezoelectric element.

Conventionally, an ultrasonic transducer configured to be able to transmit and receive ultrasonic waves based on the piezoelectric effect of a piezoelectric body is known (for example, Patent Document 1).
The ultrasonic transducer described in Patent Document 1 includes a silicon substrate having an opening formed therein, a diaphragm provided on the silicon substrate for closing the opening, and a piezoelectric element provided on the diaphragm, and these The piezoelectric element includes a lower electrode, a piezoelectric body, and an upper electrode that are sequentially stacked on the diaphragm. The ultrasonic transducer configured as described above has a resonance frequency corresponding to the planar dimension and thickness dimension of the diaphragm.

JP 2014-194993 A

By the way, in order to carry out highly accurate ultrasonic measurement, it is conceivable to use an ultrasonic transducer capable of transmitting and receiving higher frequency ultrasonic waves. In order to realize high frequency of the ultrasonic transducer in which the piezoelectric element is provided on the above-described diaphragm, for example, it is conceivable to reduce the size (area) of the vibration region of the diaphragm as viewed from the thickness direction. . For this purpose, it is necessary to reduce the area of the opening, which is not easy and has limitations.
It is also conceivable to increase the rigidity by increasing the thickness of the diaphragm. In this case, in order to improve the transmission output and reception sensitivity of the ultrasonic transducer, it is necessary to use a piezoelectric body having high piezoelectric performance, and it is desirable to form a piezoelectric body having high orientation on the lower electrode.

However, when the piezoelectric body is formed on the diaphragm, the orientation of the piezoelectric body is affected by the surface properties of the diaphragm serving as a base. For this reason, it is not easy to form a piezoelectric body having high orientation while increasing the thickness dimension of the diaphragm.
For example, when a diaphragm is formed on a silicon substrate and a piezoelectric element is formed on the diaphragm, the diaphragm is an etching stopper layer used when forming an opening in the silicon substrate by etching, or a metal constituting the piezoelectric element. It includes a barrier layer formed using a material having high resistance to the components contained in the material and the piezoelectric material. This barrier layer is formed, for example, as a sputtered film such as ZrO ₂ . However, there is a limit to increasing the thickness of the sputtered film, and the film formation time is increased and the manufacturing efficiency is deteriorated. Further, even if a thick sputtered film can be formed, it is difficult to form a film having a desired surface property. For this reason, even if the piezoelectric element is formed with the barrier layer as a base, the orientation of the piezoelectric body may be lowered, and there is a limit to improving the piezoelectric performance.
As described above, it is not easy to increase the driving frequency of the piezoelectric element, and it is not easy to increase the frequency of ultrasonic waves transmitted and received by the ultrasonic transducer.

  It is an object of the present invention to provide a piezoelectric element, a piezoelectric module, an electronic device, and a method for manufacturing the piezoelectric element that can increase the driving frequency.

  A piezoelectric element according to an application example of the present invention includes a support film, an insulating single crystal substrate provided on the support film, a lower metal electrode provided on the substrate, and the lower metal electrode. And a top metal electrode provided on the piezoelectric body, wherein the crystal plane orientation of the substrate is the same as the crystal plane orientation of the piezoelectric body.

In this application example, the piezoelectric element includes an insulating single crystal substrate provided on the support film, and a lower metal electrode, a piezoelectric body, and an upper metal electrode that are sequentially stacked on the substrate. The The substrate and the piezoelectric body have the same crystal plane orientation.
In this piezoelectric element, for example, after a single crystal substrate having a desired crystal plane orientation is provided on a support film, a lower metal electrode is formed on the substrate by a sputtering method, and a piezoelectric body is formed on the lower metal electrode. For example, it can be manufactured by forming by a sol-gel method and then forming an upper metal electrode on the piezoelectric body. For this reason, in the piezoelectric element of this application example, the crystal plane orientations of the piezoelectric body and the lower metal electrode can be made the same as the crystal plane orientation of the base substrate. Therefore, a piezoelectric body having a desired crystal plane orientation, that is, a polarization axis in a desired direction, can be formed by appropriately setting the crystal plane orientation of the substrate.
Therefore, in the piezoelectric element of this application example in which the support film and the substrate are the diaphragm, the piezoelectric performance of the piezoelectric body can be improved while increasing the thickness dimension of the diaphragm, and the drive frequency can be increased. it can. Further, by using the piezoelectric element of this application example as an ultrasonic transducer, it is possible to increase the frequency of ultrasonic waves transmitted and received.
In addition, by adjusting the thickness of the substrate as described above, the resonance frequency of the diaphragm can be adjusted, and thereby the drive frequency of the piezoelectric element and the frequency of ultrasonic waves to be transmitted and received can be set to desired values. Easy.

In the piezoelectric element of this application example, the substrate is preferably a metal oxide single crystal having substantially the same lattice constant as the piezoelectric body.
In this application example, since the substrate is a metal oxide single crystal having substantially the same lattice constant as that of the piezoelectric body, the uniformity of the piezoelectric body in the plane direction orthogonal to the thickness direction can be improved. Therefore, the piezoelectric performance of the piezoelectric body can be improved more reliably.
In this application example, the lattice constant is substantially the same as that in which the lattice constant of the substrate is the same as that of the piezoelectric body, in addition to the lattice constant of the substrate being the same. If present, it includes that the lattice constants of the substrate and the piezoelectric body are slightly different.

In the piezoelectric element of this application example, it is preferable that the substrate is a single crystal mainly containing any one of MgO, LaAlO ₃ , LaNiO ₃ , SrNiO ₃ , SrTiO ₃ , and ZrO ₂ .
In this application example, any single crystal of the above metal oxide is used as the substrate. These metal oxides are excellent in heat resistance and can be subjected to heat treatment at 700 ° C. or higher, for example. For this reason, for example, when heat treatment is performed in the manufacturing process of the lower electrode, the piezoelectric body, and the upper electrode, deterioration of the substrate can be suppressed, and a piezoelectric element having desired characteristics can be obtained more reliably.
Further, since the metal oxide has a lattice constant substantially the same as that of PZT (Pb (Zr, Ti) O ₃ ), when PZT is adopted as the piezoelectric body, the crystal plane orientation of PZT can be more reliably set to a desired value. The orientation can be achieved, and the piezoelectric performance can be improved.

In the piezoelectric element of this application example, it is preferable that the crystal plane orientation of the substrate is (100) or (111).
In this application example, the crystal plane orientation of the substrate and the piezoelectric body is (100) or (111). For example, the crystal plane orientation (100) is oriented when the piezoelectric material has a polarization axis of [111] direction, and the crystal plane orientation (100) when the piezoelectric material has a polarization axis of [001] direction. The piezoelectric performance can be improved by domain engineering that orients 111).

In the piezoelectric element according to this application example, it is preferable that the lower metal electrode includes at least one of Pt, Ir, SrRuO ₃ , Nb: SrTiO ₃ , and LaNiO ₃ as a main component.
In this application example, the lower electrode has at least one of the above materials as a main component. These electrode materials have low reactivity to oxygen. For this reason, for example, when a piezoelectric body is formed using various metal oxides, oxygen escape from the piezoelectric body can be suitably suppressed. Therefore, it is possible to suppress a decrease in piezoelectric performance due to oxygen loss.

In the piezoelectric element according to this application example, it is preferable that the lower metal electrode has the same crystal plane orientation as that of the substrate.
In this application example, the crystal plane orientation of the lower electrode is the same as the crystal plane orientation of the substrate. That is, the crystal plane orientations of the substrate, the lower electrode, and the piezoelectric body all coincide. Thereby, for example, when the lower electrode and the piezoelectric body are sequentially formed on the substrate, the crystal plane orientation of the piezoelectric body can be more reliably matched with the crystal plane orientation of the substrate.

In the piezoelectric element of this application example, the piezoelectric body includes Pb (Zr, Ti) O ₃ , PbTiO ₃ , SrBi ₂ Ta ₂ O ₉ , (Bi, La) ₄ Ti ₃ O 1 ₂ , BiFeO ₃ , BaTiO ₃ , ( It is preferable that at least one of Na, K) NbO ₃ , Pb (Ni, Nb) O ₃ , Pb (Mg, Nb) O ₃ , and ZnO is a main component.
In this application example, the piezoelectric body includes at least one of the above materials as a main component. By using these piezoelectric materials and appropriately adjusting the polarization direction, it is possible to improve the piezoelectric performance and, in turn, achieve a higher frequency.

A piezoelectric module according to an application example of the present invention includes a support film, a single crystal substrate having an insulating property provided on the support film, a lower metal electrode provided on the substrate, and the lower metal. A piezoelectric element comprising: a piezoelectric body provided on the electrode; an upper metal electrode provided on the piezoelectric body; and a wiring board electrically connected to the lower metal electrode and the upper metal electrode. And the crystal plane orientation of the substrate is the same as the crystal plane orientation of the piezoelectric body.
In this application example, similarly to the piezoelectric element of the above application example, the drive frequency of the piezoelectric element can be increased, and when the piezoelectric element is used as an ultrasonic transducer, the ultrasonic frequency can be increased. . Therefore, by performing ultrasonic measurement using the piezoelectric module of this application example, the resolution can be improved and high-accuracy ultrasonic measurement can be performed.

An electronic apparatus according to an application example of the invention includes a support film, an insulating single crystal substrate provided on the support film, a lower metal electrode provided on the substrate, and the lower metal electrode. A piezoelectric element including a piezoelectric body provided on the upper body and an upper metal electrode provided on the piezoelectric body; and a control unit that controls the piezoelectric element, wherein the crystal plane orientation of the substrate is It is the same as the crystal plane orientation of the piezoelectric body.
In this application example, similarly to the piezoelectric element of the above application example, the drive frequency of the piezoelectric element can be increased, and when the piezoelectric element is used as an ultrasonic transducer, the ultrasonic frequency can be increased. . Therefore, by performing ultrasonic measurement using the electronic apparatus of this application example, the resolution can be improved and high-accuracy ultrasonic measurement can be performed.

A method for manufacturing a piezoelectric element according to an application example of the present invention includes a single crystal substrate disposing step of providing an insulating single crystal substrate on a support film, and a lower metal electrode is formed by epitaxial growth on the substrate. A lower electrode forming step, a piezoelectric body forming step of epitaxially growing a piezoelectric body having the same crystal plane orientation as the substrate on the lower metal electrode, and an upper electrode forming an upper metal electrode on the piezoelectric body And a forming step.
In this application example, a lower electrode and a piezoelectric body are epitaxially grown in order on a single crystal substrate provided on a support film. In such a configuration, a piezoelectric body having a crystal plane orientation corresponding to a single crystal substrate and having high orientation can be formed. For example, the crystal plane orientations of the single crystal substrate and the piezoelectric body can be matched. Thereby, the piezoelectric performance of the piezoelectric body can be improved.
Therefore, in the piezoelectric element of this application example using the support film and the substrate as the diaphragm, the piezoelectric performance of the piezoelectric body can be improved while increasing the thickness dimension of the diaphragm, and the drive frequency can be increased. . Further, by using the piezoelectric element of this application example as an ultrasonic transducer, it is possible to increase the frequency of ultrasonic waves transmitted and received. Further, since it is possible to increase the frequency by increasing the thickness dimension of the substrate, it is easier to increase the frequency than to decrease the size of the vibration region of the diaphragm.

In the method for manufacturing a piezoelectric element according to this application example, it is preferable that the method includes a thickness adjustment step of adjusting the thickness of the substrate provided on the support film.
In this application example, the thickness of the single crystal substrate provided on the support film is adjusted by the thickness adjusting step. Thereby, since the thickness dimension of a board | substrate can be adjusted, the resonant frequency of a diaphragm can be adjusted and it is easy to set the frequency of the ultrasonic wave transmitted / received to a desired value.

In the method for manufacturing a piezoelectric element according to this application example, it is preferable that a plurality of the substrates are provided on the support film in the single crystal substrate disposing step.
In this application example, a plurality of single crystal substrates are provided over the supporting film. Then, a driving unit in which a lower electrode, a piezoelectric body, and an upper electrode are sequentially stacked is formed on each single crystal substrate. Thereby, when forming a some drive part on a support film, the single crystal substrate which has a plane dimension sufficient to form at least 1 drive part can be used. Therefore, an increase in manufacturing cost due to the use of a larger single crystal substrate can be suppressed.

In the method for manufacturing a piezoelectric element according to this application example, an insulating film forming step of forming an insulating film on the plurality of substrates and the supporting film, and a thickness adjusting step of adjusting the thickness of the substrate provided on the supporting film In the thickness adjusting step, the substrate and the insulating film are preferably polished from the opposite side to the support film to form a flat surface.
In this application example, an insulating film is formed between a plurality of single crystal substrates provided on a support film by an insulating film forming process, and the single crystal substrate and the insulating film are simultaneously polished by a thickness adjusting process. Is a flat surface. Since the lower electrode and the piezoelectric body can be formed on the flat surface, a piezoelectric element in which a plurality of driving units are formed on the support film can be manufactured more easily.

1 is a plan view showing a schematic configuration of an ultrasonic device according to a first embodiment of the present invention. The figure which expands and shows a part of ultrasonic device which concerns on the said embodiment. The figure which shows the manufacturing process of the ultrasonic device which concerns on the said embodiment. The figure which shows the manufacturing process of the ultrasonic device which concerns on the said embodiment. The figure which shows the manufacturing process of the ultrasonic device which concerns on the said embodiment. The figure which shows the manufacturing process of the ultrasonic device which concerns on the said embodiment. The figure which shows the manufacturing process of the ultrasonic device which concerns on the said embodiment. The figure which shows the manufacturing process of the ultrasonic device which concerns on the said embodiment. The figure which shows the manufacturing process of the ultrasonic device which concerns on the said embodiment. The figure which shows the manufacturing process of the ultrasonic device which concerns on the said embodiment. The figure which shows the manufacturing process of the ultrasonic device which concerns on the said embodiment. The figure which shows the manufacturing process of the ultrasonic device which concerns on the said embodiment. The figure which shows the manufacturing process of the ultrasonic device which concerns on the said embodiment. The figure which shows the manufacturing process of the ultrasonic device which concerns on the said embodiment. The figure which shows the manufacturing process of the ultrasonic device which concerns on the said embodiment. The figure which shows typically the ultrasonic measuring device which concerns on 2nd embodiment of this invention. The block diagram which shows schematic structure of the ultrasonic measuring device which concerns on the said embodiment.

[First embodiment]
Hereinafter, as a first embodiment according to the present invention, an ultrasonic device including an ultrasonic transducer as a piezoelectric element of the present invention will be described with reference to the drawings.
[Configuration of ultrasonic device]
FIG. 1 is a plan view schematically showing an ultrasonic device including a plurality of ultrasonic transducers. In FIG. 1, the configuration of the ultrasonic transducer is simplified. 2 is an enlarged view of the ultrasonic transducer included in the ultrasonic device shown in FIG. 1, and FIG. 2 (A) is a plan view showing a part of the ultrasonic transducer, and FIG. 2 (B). These are sectional drawings in the AA line of Drawing 2 (A), and Drawing 2 (C) is a sectional view in the BB line of Drawing 2 (A).
As shown in FIG. 1, the ultrasonic device 1 includes a plurality of ultrasonic transducers 20 formed on a device substrate 10. These ultrasonic transducers 20 are configured to be able to transmit and receive ultrasonic waves, and are arranged on the device substrate 10 in an array. In the ultrasonic device 1, a transmission / reception channel CH configured by a plurality of ultrasonic transducers 20 arranged along one direction (hereinafter also referred to as slice direction or X direction) is a direction orthogonal to the one direction ( A plurality of one-dimensional array structures arranged along the scan direction or Y direction). In the ultrasonic device 1 configured as described above, the ultrasonic transducer 20 is driven to transmit an ultrasonic wave and receive a reflected wave reflected by the measurement target. In the following description, it is assumed that the ultrasonic transducer 20 is formed on the + Z side of the device substrate 10 with the Z direction orthogonal to the X direction and the Y direction.

The device substrate 10 is made of, for example, single crystal silicon having (100), (110), or (111) orientation. In addition to the single crystal silicon, the device substrate 10 includes ceramic materials and glass ceramic materials exemplified by ZrO ₂ and Al ₂ O _3, oxide substrate materials exemplified by MgO and LaAlO ₃ , SiC, and the like. Inorganic materials as exemplified by SiO ₂ , Si ₃ N ₄ and various polycrystalline silicon can be used. Furthermore, a laminated material by a combination of these materials can be used.
The device substrate 10 is provided with an opening 11 along the thickness direction at a position corresponding to the ultrasonic transducer 20. The opening 11 defines a vibration area 21 </ b> A of the diaphragm 21. That is, the opening 11 defines the shape and dimensions of the vibration region 21 </ b> A of the diaphragm 21 in a plan view as viewed in the thickness direction of the device substrate 10.

The ultrasonic transducer 20 is provided on the device substrate 10 as described above, and includes the vibration plate 21, the lower electrode 22, the piezoelectric body 23, the upper electrode 24, and the protective film 25. In a plan view in the thickness direction of the device substrate 10 (hereinafter, also simply referred to as a plan view), a region where the lower electrode 22, the piezoelectric body 23, and the upper electrode 24 overlap constitutes a drive unit 20A of the ultrasonic transducer 20. To do. The driving unit 20A is provided at a position included in the opening 11 of the device substrate 10 in the plan view.
When transmitting ultrasonic waves, the ultrasonic transducer 20 applies a pulse voltage to the lower electrode 22 and the upper electrode 24, and vibrates the vibration plate 21 by vibrating the drive unit 20A to transmit ultrasonic waves. Further, when receiving the ultrasonic wave, the ultrasonic transducer 20 outputs the vibration of the drive unit 20A according to the vibration of the diaphragm 21 by the received ultrasonic wave as a voltage signal.

  The diaphragm 21 includes a support film 211, a single crystal substrate 212 disposed on the support film 211, a TEOS (Tetraethyl orthosilicate) film 213 (see FIG. 4E) provided between the single crystal substrates 212, It is comprised including. Among these, the vibration region 21 </ b> A of the ultrasonic transducer 20 is configured by the support film 211 and the single crystal substrate 212. The TEOS film 213 will be described later.

The support film 211 is provided so as to cover one surface of the device substrate 10 and closes one end side of the opening 11 along the thickness direction. The support film 211 is mainly composed of SiO ₂ formed by subjecting the device substrate 10 made of single crystal silicon to thermal oxidation treatment. The support film 211 functions as an etching stopper film when the opening 11 is formed in the device substrate 10 by etching as will be described later.

  The single crystal substrate 212 corresponds to the substrate of the present invention and is a metal oxide single crystal substrate having an insulating property, and is formed over the supporting film 211. In this embodiment, MgO that is a single crystal of a metal oxide is used as the single crystal substrate 212. The single crystal substrate 212 of MgO is disposed on the upper surface (a plane parallel to the XY plane) of the support film 211 so that the crystal plane orientation is (100) orientation. Further, the lattice constant of MgO is about 4.2 Å.

Note that the single crystal substrate 212 may be a single crystal substrate of a metal oxide such as ZrO ₂ . In addition to MgO, the single crystal substrate 212 may be a single crystal substrate of a perovskite metal oxide such as LaAlO ₃ , LaNiO ₃ , SrNiO ₃ , SrTiO _3, etc. In this case, the piezoelectric body 23 is a perovskite type. Deterioration due to oxygen loss when using a metal oxide can be suitably suppressed. In addition, by using the single crystal substrate 212 formed of the above-described material, lead omission contained in a piezoelectric material such as PZT can be suppressed, and the lead of the device substrate 10 due to the reaction between the lead and the device substrate 10 can be suppressed. Deterioration can be suppressed. The metal oxide is excellent in heat resistance and can be subjected to heat treatment at 700 ° C. or higher, for example. Therefore, for example, deterioration of the single crystal substrate 212 can be suppressed even when heat treatment is performed in the manufacturing process of the ultrasonic device 1.

  The lower electrode 22 corresponds to the lower metal electrode of the present invention and is provided on the diaphragm 21. The lower electrode 22 is an individual electrode provided for each transmission / reception channel CH. The lower electrode 22 includes a lower electrode body portion 221 that overlaps the piezoelectric body 23 and a lower electrode connection portion 222 that is connected to the lower electrode body portion 221 in plan view.

The lower electrode body 221 is located between the single crystal substrate 212 and the piezoelectric body 23 of the vibration plate 21 and is formed by epitaxial growth on the single crystal substrate 212 as will be described later. The lower electrode main body 221 has a (100) orientation in the crystal plane, and the crystal plane orientation matches that of the single crystal substrate 212. The lower electrode main body 221 contains at least one of Pt, Ir, SrRuO ₃ , Nb: SrTiO ₃ , LaNiO _3, etc. as a main component. In the present embodiment, the lower electrode main body 221 is formed using Pt so as to have a thickness dimension of about 200 nm. The lattice constant of Pt is about 3.9%, which is almost the same as the number of lattices of MgO forming the single crystal substrate 212.
In addition, by using a metal oxide such as SrRuO ₃ , Nb: SrTiO ₃ , LaNiO ₃ or the like for the lower electrode body 221, oxygen depletion is suppressed when, for example, a perovskite transition metal oxide is used as the piezoelectric body 23. It is possible to suppress the deterioration of the piezoelectric performance of the piezoelectric body 23.

The lower electrode connection part 222 is a wiring electrode extending in the ± X direction from the lower electrode main body part 221. That is, the lower electrode connecting part 222 connects the lower electrode main body part 221 of the ultrasonic transducer 20 constituting the same channel. In addition, the lower electrode connecting portion 222 is an electrode terminal for the lower electrode 22 that is connected to a drive circuit (not shown) of the ultrasonic device 1 at both ends along the Y direction of each transmission / reception channel CH. Is formed.
The lower electrode connecting portion 222 includes a lower layer 222A provided on the diaphragm 21, an intermediate layer 222B provided so as to cover the lower layer 222A, and an upper layer 222C provided on the intermediate layer 222B. The lower layer 222A is formed simultaneously with the lower electrode body 221. In the present embodiment, the lower layer 222A is formed using Pt so as to have a thickness dimension of about 200 nm, like the lower electrode body 221. The intermediate layer 222B is formed using Ir so as to have a thickness dimension of about 40 nm. The upper layer 222C is provided on the intermediate layer 222B and is formed using a wiring material having a relatively high electrical conductivity such as Au, Cu, Al, Ag, etc. In this embodiment, a film of about 1 μm is formed using Au. It is formed with a thickness dimension. Thereby, the electrical conductivity of the lower electrode 22 can be improved.

The piezoelectric body 23 includes a first piezoelectric film 231 and a second piezoelectric film 232 and is formed on the lower electrode body 221.
The first piezoelectric film 231 and the second piezoelectric film 232 are formed by, for example, Pb (Zr, Ti) O ₃ that is an oxide having a perovskite structure including lead (Pb), titanium (Ti), and zirconium (Zr). The In this embodiment, it is made of lead zirconate titanate (for example, PZT; Zr / Ti = 55/45 composition). In this composition, PZT is rhombohedral and its polarization axis is in the [111] direction. In addition, the first piezoelectric film 231 and the second piezoelectric film 232 are formed by epitaxial growth with respect to the lower layer (for example, the first piezoelectric film 231 is on the single crystal substrate 212), and the crystal plane orientation is ( 100) orientation and a lattice constant of about 3.8Å. That is, the crystal plane orientation of the piezoelectric body 23 matches the single crystal substrate 212 and the lower electrode 22. The lattice constant of the piezoelectric body 23 is substantially the same as that of the single crystal substrate 212 and the lower electrode 22.

The upper electrode 24 corresponds to the upper metal electrode of the present invention, and is a common electrode for the plurality of ultrasonic transducers 20. The upper electrode 24 includes an element electrode part 241 provided across a plurality of ultrasonic transducers 20 arranged in the Y direction, and a common electrode part 242 that connects ends of the element electrode parts 241 parallel to each other. Have The common electrode portion 242 is a wiring electrode, and electrode terminals for the upper electrode 24 for connection to a drive circuit (not shown) of the ultrasonic device 1 are formed at both ends in the X direction.
Among these, the element electrode part 241 includes a first conductor layer 24A and a second conductor layer 24B at positions corresponding to the ultrasonic transducers 20. The element electrode portion 241 includes a second conductor layer 24B and a third conductor layer 24C at positions between the ultrasonic transducers 20. Similarly, the common electrode portion 242 includes a second conductor layer 24B and a third conductor layer 24C.

The first conductor layer 24A is provided on the piezoelectric body 23 and improves the adhesion between the piezoelectric body 23 and the second conductor layer 24B. The first conductor layer 24A is made of a conductor whose main component is at least one of Ti, Pt, Ir, SrRuO ₃ , and LaNiO ₃ . In this embodiment, the film is formed with a film thickness of about 10 nm using Ir.

The second conductor layer 24B constitutes the element electrode portion 241 as described above, and is provided across the plurality of ultrasonic transducers 20 arranged in the Y direction. Further, the common electrode portion 242 is configured as described above, and is formed along the X direction on the ± Y side of the region where the ultrasonic transducer 20 is provided. The second conductor layer 24B is made of a conductor whose main component is at least one of Ti, Pt, Ir, SrRuO ₃ , and LaNiO ₃ . In this embodiment, the film is formed with a film thickness of about 40 nm using Ir.

  The third conductor layer 24 </ b> C is provided so as to cover a part of the second conductor layer 24 </ b> B excluding a region overlapping with the opening 11 in plan view. The third conductor layer 24C is formed using a wiring material having a relatively high electrical conductivity such as Au, Cu, Al, Ag, and the like. In the present embodiment, the third conductor layer 24C includes at least an Au layer having a thickness of about 1 μm. Composed. Thereby, the electrical conductivity of the upper electrode 24 can be improved.

  The protective film 25 is at least a part of the outer periphery of the lower layer 222A and the intermediate layer 222B of the lower electrode connection portion 222, the piezoelectric body 23, and the first conductor layer 24A and the second conductor layer 24B of the upper electrode 24. It is provided in the position which covers. The protective film 25 is also provided on the diaphragm 21. By forming the protective film 25, it is possible to prevent the vibration plate 21 and the piezoelectric body 23 from being deteriorated due to moisture intrusion.

[Method of manufacturing ultrasonic device]
Next, a method for manufacturing the above-described ultrasonic device 1 will be described with reference to the drawings.
FIG. 3 is a flowchart showing a method for manufacturing the ultrasonic device 1 of the present embodiment. 4 to 15 are diagrams schematically illustrating the manufacturing process of the ultrasonic device 1. 6 to 11, (B) is a cross-sectional view taken along line AA shown in (A). Moreover, in FIGS. 12-15, (B) is sectional drawing along CC line shown to (A). Moreover, in FIGS. 6-15, (C) is sectional drawing along the BB line shown to (A).
In this embodiment, after disposing the single crystal substrate 212 on the device substrate 10, a part of the lower electrode 22 and the piezoelectric body 23 are epitaxially grown in order, and the upper electrode 24 is formed on the piezoelectric body 23. Then, the opening 11 is formed at a position corresponding to the piezoelectric body 23 of the device substrate 10. Thereby, the ultrasonic device 1 having a plurality of ultrasonic transducers 20 provided on the device substrate 10 is manufactured.

In the manufacture of the ultrasonic device 1, first, the support film 211 constituting the vibration plate 21 is formed on the + Z side surface of the device substrate 10 made of Si (step S1: support film forming step in FIG. 3). In step S <b> 1, a thermal oxidation process is performed on the + Z side surface of the device substrate 10. Thereby, Si on the surface of the device substrate 10 is oxidized to form the support film 211 mainly composed of SiO ₂ . In the present embodiment, the support film 211 is formed to have a thickness dimension of about 400 nm, for example.

  Next, as shown in FIGS. 4B and 5, the single crystal substrate 212 is provided on the support film 211 (step S <b> 2 in FIG. 3: single crystal substrate disposing step). In this step S2, the MgO single crystal substrate 212 whose surface is mirror-finished in advance is subjected to SPM (Sulfuric. Acid Hydrogen Peroxide Mixture) treatment, washed with sulfated water, and then subjected to APM (Ammonium Hydrogen Peroxide Mixture) treatment. Wash with ammoniated water to clean the surface and make it hydrophilic. After that, as shown in FIG. 5, the single crystal substrate 212 (in this embodiment, the dimensions in the X direction and the Y direction are 2 cm) at positions corresponding to each of the plurality of ultrasonic transducers 20 on the support film 211. It arrange | positions and performs temporary joining and this joining is performed by heat processing (about 1000 degreeC). Note that FIG. 5 illustrates the case where 36 single crystal substrates 212 are provided over the supporting film 211 as an example, but the number of single crystal substrates 212 is not limited.

Next, as shown in FIG. 4C, the single crystal substrate 212 is polished (roughly polished) by mechanical polishing so that the thickness dimension is, for example, 3000 to 10000 nm.
Next, as shown in FIG. 4D, a TEOS film 213 is formed over the supporting film 211 and the single crystal substrate 212 (step S3 in FIG. 3: TEOS film forming process (insulating film forming process)). In this embodiment, the TEOS film 213 is formed by CVD on the single crystal substrate 212 and the support film 211 that is not provided with the single crystal substrate 212 and is exposed. The TEOS film 213 is formed so that the film thickness on the support film 211 is equal to or greater than the design value of the film thickness of the diaphragm 21. Thereby, the upper surface of the single crystal substrate 212 and the TEOS film 213 can be made the same height in the subsequent polishing process of the vibration plate 21. The TEOS film 213 has an insulating property and corresponds to the insulating film of the present invention. The TEOS film 213 is a protective film for the support film 211, and the upper surface of the TEOS film 213 is a formation surface of the lower electrode 22 and the piezoelectric body 23.

  Next, as shown in FIG. 4E, the single crystal substrate 212 and the TEOS film 213 are polished by chemical mechanical polishing to adjust the film thickness of the diaphragm 21 (step S4 in FIG. 3: diaphragm). Thickness adjustment step). In this step S4, the film thickness in the vibration region 21A of the vibration plate 21 formed by the support film 211 and the single crystal substrate 212 according to the driving frequency (that is, the transmission frequency and the reception frequency) of the ultrasonic transducer 20, For example, it is adjusted to about 50 to 3000 nm. By increasing the film thickness dimension of the vibration region 21A, the rigidity of the diaphragm 21 can be increased, and the drive frequency can be increased. In step S4, the upper surface 21B of the diaphragm 21 is made flat by polishing the single crystal substrate 212 and the TEOS film 213. On the top surface of the single crystal substrate 212, a (100) -oriented surface is exposed.

Next, as shown in FIGS. 6 and 7, the lower electrode 22 is formed on the vibration plate 21 (step S5 in FIG. 3: lower electrode forming step).
In step S5, as shown in FIG. 6, first, a Pt layer (for example, 200 nm) M1 as the lower electrode 22 is formed by sputtering. The film-forming conditions for the Pt layer M1 are preferably high temperature and low power. For example, the film-forming conditions include an applied power of about 100 W at a temperature of 400 ° C. or higher. Thereby, the Pt layer M1 can be epitaxially grown on the single crystal substrate 212. In the present embodiment, the crystal plane orientation of the Pt layer M1 is the (100) orientation at the position overlapping the single crystal substrate 212 in plan view, and coincides with the single crystal substrate 212.

  Next, a PZT layer (for example, 120 nm) as the first piezoelectric film 231 is formed on the Pt layer M1 immediately after being formed by a sol-gel method. That is, the first piezoelectric film 231 is formed by applying a PZT solution on the Pt layer M1 by spin coating, and performing a drying step, a degreasing step, and a firing step. Thereby, the PZT layer can be epitaxially grown at a position overlapping the single crystal substrate 212 in plan view. In the present embodiment, the crystal plane orientation of the first piezoelectric film 231 is the (100) orientation at the position overlapping the single crystal substrate 212 in plan view, and coincides with the single crystal substrate 212.

  Next, as shown in FIG. 7, the Pt layer M1 and the first piezoelectric film 231 are patterned and formed into a desired shape. The patterning of the Pt layer M1 and the first piezoelectric film 231 is performed, for example, by forming a mask by a photolithography method and removing portions other than the mask areas of the Pt layer M1 and the first piezoelectric film 231 by dry etching. . In this way, the lower electrode main body portion 221 of the lower electrode 22 and the lower layer 222A (see FIG. 2) of the lower electrode connecting portion 222 are formed.

Next, as shown in FIGS. 8 to 10, the second piezoelectric film 232 is formed so as to cover the first piezoelectric film 231 to form the piezoelectric body 23 (step S <b> 6 in FIG. 3: piezoelectric body forming step). ).
In step S6, as shown in FIG. 8, first, similarly to the first piezoelectric film 231, a PZT layer (for example, 1200 nm) as the second piezoelectric film 232 is formed by the sol-gel method, and the lower electrode body 221 is formed. The PZT layer is epitaxially grown above. That is, in the present embodiment, the crystal plane orientation of the second piezoelectric film 232 is (100) orientation, and coincides with the single crystal substrate 212, the lower electrode main body part 221, and the first piezoelectric film 231 located in the lower layer. ing.

Next, as shown in FIG. 9, an Ir layer (for example, 10 nm) M2 is formed as the first conductor layer 24A constituting the upper electrode 24 by sputtering.
Then, as shown in FIG. 10, the Ir layer M2 and the second piezoelectric film 232 are patterned to form the first conductor layer 24A and the piezoelectric body 23. The patterning of the Ir layer M2 and the second piezoelectric film 232 is performed by photolithography and dry etching. In the present embodiment, the second piezoelectric film 232 is formed so as to cover the lower electrode body 221 by forming a photomask larger than the lower electrode body 221 in plan view. Further, the Ir layer M2 and the second piezoelectric film 232 formed on the single crystal substrate 212 and the lower electrode connecting portion 222 in plan view are removed. For this reason, the lower layer 222A of the lower electrode connection part 222 is exposed.

Next, as shown in FIGS. 11 and 12, the second conductor layer 24B of the upper electrode 24 is formed (step S7 in FIG. 3: upper electrode forming step).
In step S6, as shown in FIG. 11, first, an Ir layer (as the second conductor layer 24B of the upper electrode 24) and the intermediate layer 222B of the lower electrode connecting part 222 constituting the lower electrode 22 and the second electrode 22 are formed by sputtering. For example, 40 nm) M3 is formed.
Next, as shown in FIG. 12, the Ir layer is patterned to form the intermediate layer 222B and the second conductor layer 24B. The patterning of the Ir layer is performed by photolithography and dry etching. 12B, the first conductor layer 24A and the second conductor layer 24B of the upper electrode 24 are partially removed, and the intermediate layer 222B of the lower electrode connection portion 222 and the upper electrode 24 are removed. The second conductor layer 24B is separated, that is, the lower electrode 22 and the upper electrode 24 are separated.

Next, as shown in FIG. 13, a protective film 25 is formed (step S8 in FIG. 3: protective film forming step). In step S8, an Al ₂ O ₃ film (for example, 90 nm) is formed by ALCVD (Atomic Layer Chemical Vapor Deposition) (atomic layer chemical vapor deposition method), and the formed Al ₂ O ₃ film is formed by photolithography and dry etching. The protective film 25 is formed by patterning. As shown in FIG. 13B, the insulating property between the lower electrode 22 and the upper electrode 24 can be improved by forming a protective film 25 at the separation portion between the lower electrode 22 and the upper electrode 24. it can. Further, by forming the protective film 25 at a position covering the piezoelectric body 23 exposed at the separation portion or a position covering the vibration plate 21, deterioration of the vibration plate 21 and the piezoelectric body 23 due to intrusion of moisture or the like can be suppressed. .

Next, as shown in FIG. 14, the upper layer 222C of the lower electrode connecting portion 222, which is a wiring electrode,
Then, the third conductor layer 24C of the upper electrode 24 is formed (step S9 in FIG. 3: wiring formation step). In step S9, a metal layer is formed as the upper layer 222C and the third conductor layer 24C. Specifically, for example, a NiCr layer (50 nm) and an Au layer (300 nm) are sequentially formed by sputtering and then patterned to remove the metal layers other than the formation positions of the upper layer 222C and the third conductor layer 24C. To do. Thereafter, an Au layer (1 μm) is formed by electroplating to form the upper layer 222C and the third conductor layer 24C.

Next, as shown in FIGS. 2 and 15, the device substrate 10 is formed into a desired shape (step S10 in FIG. 3: device substrate forming step).
In step S10, first, as shown in FIG. 15, the device substrate 10 is ground from the back surface (the surface opposite to the vibration plate 21), and the thickness of the device substrate 10 is set to 150 μm, for example.
Then, as shown in FIG. 2, the opening 11 is formed at a position corresponding to each ultrasonic transducer 20 of the device substrate 10. Specifically, for example, a photomask is formed by photolithography, and the device substrate 10 is processed by inductive coupled plasma (RIE) to form the opening 11, and the support film 211 is formed. To expose.
In this way, the ultrasonic device 1 including the plurality of ultrasonic transducers 20 is manufactured.

[Operational effects of the first embodiment]
In the present embodiment, the ultrasonic transducer 20 includes an insulating single crystal substrate 212 provided on the support film 211, a lower electrode 22, a piezoelectric body 23, and an upper portion sequentially stacked on the single crystal substrate 212. And an electrode 24. Lower electrode 22 is formed by sputtering and is epitaxially grown on single crystal substrate 212. In addition, the piezoelectric body 23 is formed in the region of the lower electrode 22 epitaxially grown on the single crystal substrate 212 under the film-forming conditions for epitaxial growth. The thus formed lower electrode 22 (lower electrode main body portion 221) and piezoelectric body 23 have the same crystal plane orientation as that of the single crystal substrate 212, and are (100) oriented in this embodiment.

In the ultrasonic transducer 20 formed in this way, it is easy to make the crystal plane orientation of the lower electrode 22 and the piezoelectric body 23 the same as the crystal plane orientation of the single crystal substrate 212 as a base, and A piezoelectric body having high orientation can be formed. That is, when the layer formed by the sputtering method is used as a base, the surface uniformity in the surface direction tends to be lower than in the case where the single crystal substrate 212 is used as the base, and the surface direction (X Direction and Y direction) are also reduced, and the piezoelectric performance is likely to deteriorate. On the other hand, by using the single crystal substrate 212 as a base, it is possible to form the piezoelectric body 23 that is more uniform not only in the thickness direction (Z direction) of the piezoelectric body 23 but also in the plane direction. Can be improved. In addition, the piezoelectric body 23 having desired piezoelectric performance can be formed by appropriately setting the type and crystal plane orientation of the single crystal substrate 212 according to the material constituting the piezoelectric body 23.
In addition, since the single crystal substrate 212 is a metal oxide single crystal having substantially the same lattice constant as that of the piezoelectric body 23, the uniformity of the piezoelectric body in the plane direction can be improved. Therefore, the piezoelectric performance of the piezoelectric body can be improved more reliably.

Here, by reducing the opening size of the opening 11 to reduce the area of the vibration region 21 </ b> A or increasing the rigidity of the vibration plate 21, the frequency of ultrasonic waves transmitted and received by the ultrasonic transducer 20 is increased. Can be achieved. However, since there is a limit to reducing the opening size, it is desirable to increase the frequency by increasing the rigidity of the diaphragm by increasing the thickness of the diaphragm. However, when a diaphragm is formed on a silicon substrate by a sputtering method and a drive unit including a piezoelectric body is formed on the diaphragm, there is a limit to increasing the thickness of the diaphragm. In addition, as described above, the surface of the sputtered film tends to be less uniform, and it is more difficult to improve the surface uniformity while increasing the thickness.
On the other hand, in the present embodiment, the single crystal substrate 212 is also provided for the device substrate 10 which is a single crystal silicon substrate, and the lower electrode 22 and the piezoelectric body 23 are provided with the single crystal substrate 212 as a base as described above. Epitaxially grow. As a result, the piezoelectric body 23 having high piezoelectric performance can be formed. As a result, the ultrasonic transducer 20 can have a higher frequency. In addition, the resonance frequency of the diaphragm can be adjusted by adjusting the thickness of the single crystal substrate 212 and adjusting the rigidity of the diaphragm 21, whereby the frequency of ultrasonic waves to be transmitted and received is set to a desired value. It is also easy to do.

  In this embodiment, an MgO single crystal substrate is used as the single crystal substrate 212. MgO is excellent in heat resistance and can be subjected to heat treatment at 700 ° C. or higher, for example. Therefore, even if the heat treatment is performed in the manufacturing process of the ultrasonic device 1, the deterioration of the single crystal substrate 212 can be suppressed. Can be suppressed. Therefore, a piezoelectric element having desired characteristics can be obtained more reliably.

In this embodiment, the single crystal substrate 212 has a crystal plane orientation of (100). The piezoelectric body 23 is a rhombohedral crystal formed of PZT and having a crystal plane orientation of (100). With such a configuration, it is possible to domain-engineer the crystal plane orientation to (100) with respect to the polarization axis [111] of the piezoelectric body 23, and to improve the piezoelectric performance of the piezoelectric body 23.
In addition, since high piezoelectric performance can be obtained by using PZT, it is possible to increase the frequency of the ultrasonic transducer 20 more reliably.

  In the present embodiment, the lower electrode main body 221 of the lower electrode 22 on which the piezoelectric body 23 is formed has Pt as a main component. Since Pt has low reactivity to oxygen, oxygen release from PZT, which is various metal oxides, can be suitably suppressed. Therefore, it is possible to suppress a decrease in piezoelectric performance due to oxygen loss.

  Pt has substantially the same number of lattices as MgO constituting the single crystal substrate 212 and PZT constituting the piezoelectric body 23. The lower electrode main body 221 is formed by epitaxial growth on the single crystal substrate 212, and the crystal plane orientation is (100) orientation, which coincides with the single crystal substrate 212 and the piezoelectric body 23. In such a configuration, the crystal plane orientation of the piezoelectric body 23 formed on the lower electrode main body portion 221 can be more reliably matched with the single crystal substrate 212. Further, the uniformity in the surface direction of the lower electrode main body 221 can be improved, and as a result, the uniformity of the piezoelectric body can be improved more reliably.

  In the present embodiment, a plurality of single crystal substrates 212 are provided on the support film 211, and the driving unit 20 </ b> A is formed on each single crystal substrate 212. Thereby, when the plurality of drive units 20A are formed on the support film 211, the single crystal substrate 212 having a planar dimension sufficient to form one drive unit 20A can be used. Therefore, the manufacturing cost can be suppressed as compared with the case of using a single crystal substrate having a size capable of forming a plurality of driving units 20A simultaneously.

  In this embodiment, a TEOS film formation step of forming a TEOS film 213 that is an insulating protective film is performed between the plurality of single crystal substrates 212 provided on the support film 211 and on the single crystal substrate 212. A TEOS film is formed, and the single crystal substrate 212 and the TEOS film 213 are simultaneously polished by a thickness adjusting step, whereby the upper surface 21B of the diaphragm 21 is made flat. Since the lower electrode 22 and the piezoelectric body 23 can be formed on the flat surface, the ultrasonic transducer 20 in which the plurality of drive units 20A are formed on the support film 211 can be more easily manufactured. .

[Second Embodiment]
Next, a second embodiment according to the present invention will be described.
In the second embodiment, an ultrasonic measuring device including the ultrasonic device 1 described in the first embodiment will be described based on the drawings.
In the following description, the same configurations and the same processes as those in the first embodiment are denoted by the same reference numerals, and the description thereof is omitted or simplified.

[Configuration of ultrasonic measuring machine]
FIG. 16 is a perspective view showing a schematic configuration of the ultrasonic measuring instrument 100 of the present embodiment. FIG. 17 is a block diagram showing a schematic configuration of the ultrasonic measuring device 100.
As shown in FIG. 16, the ultrasonic measuring device 100 according to the present embodiment includes an ultrasonic probe 110 and a control device 120 that is electrically connected to the ultrasonic probe 110 via a cable.
The ultrasonic measuring device 100 causes the ultrasonic probe 110 to come into contact with the surface of a living body (for example, a human body), and transmits ultrasonic waves from the ultrasonic probe 110 into the living body. In addition, the ultrasonic wave reflected by the organ in the living body is received by the ultrasonic probe 110, and based on the received signal, for example, an internal tomographic image in the living body is obtained, or the state of the organ in the living body (for example, Blood flow etc.).

[Configuration of ultrasonic probe]
As shown in FIG. 17, the ultrasonic probe 110 includes the ultrasonic device 1, a circuit board 111, an acoustic lens 112 (see FIG. 16), and a housing 113 (see FIG. 16) that houses them. The ultrasonic sensor 114 includes the ultrasonic device 1 and the circuit board 111. The ultrasonic sensor 114 corresponds to the piezoelectric module of the present invention.

[Configuration of acoustic lens]
The acoustic lens 112 efficiently propagates the ultrasonic wave transmitted from the ultrasonic device 1 to the living body that is the measurement target, and efficiently propagates the ultrasonic wave reflected in the living body to the ultrasonic device 1. The acoustic lens 112 is disposed along a surface on which the ultrasonic device 1 transmits and receives ultrasonic waves. Although illustration is omitted, an acoustic matching layer is provided between the ultrasonic device 1 and the acoustic lens 112. The acoustic lens 112 and the acoustic matching layer are set to an acoustic impedance intermediate between the acoustic impedance of the ultrasonic transducer 20 and the acoustic impedance of the living body.

[Case configuration]
As shown in FIG. 16, the housing 113 is formed in a box shape having a rectangular shape in plan view, and a sensor window 113 </ b> B is provided on one surface (sensor surface 113 </ b> A) orthogonal to the thickness direction. Some are exposed. The housing 113 is provided with a cable passage hole. This cable is connected to the circuit board 111.
In the present embodiment, a configuration example in which the ultrasonic probe 110 and the control device 120 are connected using a cable is shown. However, the present invention is not limited to this, and for example, the ultrasonic probe 110 and the control device 120 communicate wirelessly. And the various configurations of the control device 120 may be provided in the ultrasonic probe 110.

[Configuration of circuit board]
The circuit board 111 corresponds to the wiring board of the present invention, and is a board to which the ultrasonic device 1 is attached. A driver circuit for driving the ultrasonic device 1 is provided. Specifically, as shown in FIG. 17, the circuit board 111 includes a selection circuit 111A, a transmission circuit 111B, and a reception circuit 111C.

Based on the control of the control device 120, the selection circuit 111A switches between a transmission connection that connects the ultrasonic device 1 and the transmission circuit 111B and a reception connection that connects the ultrasonic device 1 and the reception circuit 111C.
When the transmission circuit 111B is switched to the transmission connection under the control of the control device 120, the transmission circuit 111B outputs a transmission signal to the effect that the ultrasonic device 1 transmits ultrasonic waves via the selection circuit 111A.
When the reception circuit 111C is switched to the reception connection under the control of the control device 120, the reception circuit 111C outputs the reception signal input from the ultrasonic device 1 to the control device 120 via the selection circuit 111A. The reception circuit 111C includes, for example, a low noise amplification circuit, a voltage control attenuator, a programmable gain amplifier, a low pass filter, an A / D converter, and the like. The reception circuit 111C converts the received signal into a digital signal, removes noise components, and the like. After performing each signal processing such as amplification to a signal level, the processed received signal is output to the control device 120.

[Configuration of control device]
As illustrated in FIG. 17, the control device 120 includes, for example, an operation unit 121, a display unit 122, a storage unit 123, and a calculation unit 124. For example, a terminal device such as a tablet terminal, a smartphone, or a personal computer may be used as the control device 120, or a dedicated terminal device for operating the ultrasonic probe 110 may be used.
The operation unit 121 is a user interface (UI) for the user to operate the ultrasonic measuring device 100, and can be configured by, for example, a touch panel provided on the display unit 122, operation buttons, a keyboard, a mouse, or the like. .
The display unit 122 is configured by a liquid crystal display, for example, and displays an image.
The storage unit 123 stores various programs and various data for controlling the ultrasonic measuring device 100.
The calculation unit 124 corresponds to the control unit of the present invention, and includes, for example, a calculation circuit such as a CPU (Central Processing Unit) and a storage circuit such as a memory. Then, the calculation unit 124 reads and executes various programs stored in the storage unit 123 to control transmission signal generation and output processing with respect to the transmission circuit 111B, and with respect to the reception circuit 111C. Controls frequency setting and gain setting.

[Operational effects of the second embodiment]
The ultrasonic measuring instrument 100 according to the second embodiment can obtain the same operational effects as those of the first embodiment, and can increase the frequency of ultrasonic waves transmitted and received in the ultrasonic device 1. The resolution can be improved. Therefore, it is possible to provide the ultrasonic sensor 114 and the ultrasonic measuring device 100 capable of performing highly accurate ultrasonic measurement.

[Modification]
Note that the present invention is not limited to the above-described embodiments, and the present invention includes configurations obtained by modifying, improving, and appropriately combining the embodiments as long as the object of the present invention can be achieved. Is.
In each of the above embodiments, the configuration using Pb (Zr, Ti) O ₃ as the piezoelectric body 23 is exemplified, but the present invention is not limited to this. For _{example, PbTiO 3, SrBi 2 Ta 2} O 9, (Bi, La) 4 Ti 3 O1 2, BiFeO 3, BaTiO 3, (Na, K) NbO 3, Pb (Ni, Nb) O 3, Pb (Mg, The piezoelectric body 23 may be formed using various piezoelectric materials such as Nb) O ₃ and ZnO. By using the perovskite metal oxide, the piezoelectric body 23 having good piezoelectric characteristics can be formed.

  In each of the embodiments described above, the piezoelectric body 23 is configured by the two-layer piezoelectric film of the first piezoelectric film 231 and the second piezoelectric film 232, but the present invention is not limited to this. For example, the piezoelectric body 23 may be composed of a single piezoelectric film, or may be composed of three or more piezoelectric films. Further, when the piezoelectric film is composed of a plurality of layers, each piezoelectric film may be formed of different materials.

  In each of the above embodiments, in the drive unit 20A, the single crystal substrate 212, the lower electrode 22, and the piezoelectric body 23 have the same lattice constant. However, the present invention is not limited to this, and the lattice constant is Different values may be used. Even in this case, the piezoelectric body 23 having high orientation in the thickness direction can be formed. Therefore, it is possible to increase the rigidity of the diaphragm 21 while improving the piezoelectric characteristics of the piezoelectric body 23, and to increase the frequency of the ultrasonic transducer 20. Since the single crystal substrate 212, the lower electrode 22, and the piezoelectric body 23 have substantially the same lattice constant, the piezoelectric body 23 that is more uniform in the in-plane direction can be formed. , 212 are preferably substantially the same.

  In each of the above embodiments, the configuration in which the crystal plane orientations of the single crystal substrate 212 and the piezoelectric body 23 are set to the (100) orientation is illustrated, but the present invention is not limited to this, and for example, the single crystal substrate 212 and the piezoelectric body 23 The crystal plane orientation may be (111) orientation. In this case, the piezoelectric body 23 is formed of PZT (Zr / Ti = 30/70 composition), for example. In this composition, PZT is a tetragonal crystal, and its polarization axis is in the [001] direction. A domain 23 having a crystal plane orientation of (111) with respect to the polarization axis [001] can be domain-engineered to form the piezoelectric body 23 having high piezoelectric performance.

  In each of the above embodiments, in the drive unit 20A, the configuration in which the crystal plane orientation of the lower electrode 22 is the same as the crystal plane orientation of the single crystal substrate 212 is exemplified, but the present invention is not limited to this. For example, by adopting a configuration in which the crystal plane orientation of the lower electrode 22 is different from that of the single crystal substrate 212, but the crystal plane orientation corresponding to the single crystal substrate 212 is adopted, and the piezoelectric body 23 is epitaxially grown on the lower electrode 22. The piezoelectric body 23 having a desired crystal plane orientation can be formed. In this case, the piezoelectric body 23 may have a crystal plane orientation different from that of the single crystal substrate 212.

  In each of the above embodiments, the manufacturing method of forming one driving unit 20A on one single crystal substrate 212 is exemplified, but the present invention is not limited to this. For example, a configuration in which a plurality of driving units 20A are formed on one single crystal substrate 212 may be employed. In addition, it can suppress that a vibration is transmitted between 20 A of drive parts by providing each drive part 20A on the isolate | separated single crystal substrate 212, respectively.

  In each of the above embodiments, the ultrasonic transducer 20 exemplifies a configuration for transmitting and receiving ultrasonic waves. However, an ultrasonic transducer for transmission (transmission transducer) that transmits ultrasonic waves and an ultrasonic wave are received. A receiving ultrasonic transducer (receiving transducer) may be provided separately. In this case, for example, the transmission area in which the transducers for transmission are arranged in an array and the reception area in which the transducers for reception are arranged in an array may be provided in different areas. Deucers may be placed.

  In the second embodiment described above, the ultrasonic measurement device whose target is a living body is illustrated, but the present invention is not limited to this. For example, the present invention can be applied to electronic devices that detect various structures and detect defects or perform aging inspections using various structures as measurement targets. Further, for example, the present invention can be applied to an electronic device that detects a defect of the measurement target using a semiconductor package, a wafer, or the like as the measurement target.

In each said embodiment, although illustrated about the ultrasonic device 1 which uses a piezoelectric element as an ultrasonic transducer, this invention is not limited to this, This invention is applicable also to a piezoelectric device provided with a piezoelectric element. Such a piezoelectric device can be used, for example, as an ink ejection mechanism in an inkjet head of an inkjet recording apparatus that performs drawing by ejecting ink. In this case, an ink jet recording apparatus can be exemplified as the electronic apparatus of the present invention. When the present invention is applied to a piezoelectric element of an inkjet head, a (100) -oriented Si substrate is thermally oxidized to form a support film that is a SiO ₂ film, and a single crystal substrate (100) is formed on the support film. (1) A configuration in which LaAlO ₃ having an orientation is provided and a drive unit is formed on a single crystal substrate in the same manner as in the above embodiment can be exemplified.
In addition to the above, the present invention can also be applied as a stress sensor for detecting stress (pressure, shearing force, etc.) applied to the piezoelectric element.

  In addition, the specific structure for carrying out the present invention may be configured by appropriately combining the above-described embodiments and modifications within the scope that can achieve the object of the present invention, and may be appropriately changed to other structures and the like. May be.

  DESCRIPTION OF SYMBOLS 1 ... Ultrasonic device, 10 ... Device board | substrate, 11 ... Opening part, 20 ... Ultrasonic transducer, 20A ... Drive part, 21 ... Vibrating plate, 21A ... Vibration area, 21B ... Upper surface, 22 ... Lower electrode, 23 ... Piezoelectric 24, upper electrode, 24 A, first conductor layer, 24 B, second conductor layer, 24 C, third conductor layer, 25, protective film, 211, support film, 212, single crystal substrate, 213, TEOS Membrane, 221... Lower electrode body portion, 222... Lower electrode connection portion, 222 A... Lower layer, 222 B... Intermediate layer, 222 C. Upper layer, 231 ... First piezoelectric film, 232. 242 ... Common electrode part, CH ... Transmission / reception channel, 100 ... Ultrasonic measuring device, 110 ... Ultrasonic probe, 111 ... Circuit board.

Claims (13)

A support membrane;
An insulating single crystal substrate provided on the support film;
A lower metal electrode provided on the substrate;
A piezoelectric body provided on the lower metal electrode;
An upper metal electrode provided on the piezoelectric body,
The piezoelectric element, wherein the crystal plane orientation of the substrate is the same as the crystal plane orientation of the piezoelectric body. The piezoelectric element according to claim 1.
The piezoelectric element, wherein the substrate is a single crystal of metal oxide having substantially the same lattice constant as the piezoelectric body. The piezoelectric element according to claim 1 or 2,
The piezoelectric element, wherein the substrate is a single crystal mainly composed of any one of MgO, LaAlO ₃ , LaNiO ₃ , SrNiO ₃ , SrTiO ₃ , and ZrO ₂ . The piezoelectric element according to any one of claims 1 to 3,
The crystal plane orientation of the substrate is (100) or (111). In the piezoelectric element according to any one of claims 1 to 4,
The lower metal electrode is mainly composed of at least one of Pt, Ir, SrRuO ₃ , Nb: SrTiO ₃ , and LaNiO ₃ . The piezoelectric element according to any one of claims 1 to 5,
The piezoelectric element, wherein the lower metal electrode has the same crystal plane orientation as that of the substrate. The piezoelectric element according to any one of claims 1 to 6,
The piezoelectric _{body, Pb (Zr, Ti) O} 3, PbTiO 3, SrBi 2 Ta 2 O 9, (Bi, La) 4 Ti 3 O1 2, BiFeO 3, BaTiO 3, (Na, K) NbO 3, Pb A piezoelectric element comprising at least one of (Ni, Nb) O ₃ , Pb (Mg, Nb) O ₃ , and ZnO as a main component. A support film; an insulating single crystal substrate provided on the support film; a lower metal electrode provided on the substrate; a piezoelectric body provided on the lower metal electrode; A piezoelectric element comprising an upper metal electrode provided on the body;
A wiring board electrically connected to the lower metal electrode and the upper metal electrode,
The piezoelectric module according to claim 1, wherein a crystal plane orientation of the substrate is the same as a crystal plane orientation of the piezoelectric body. A support film; an insulating single crystal substrate provided on the support film; a lower metal electrode provided on the substrate; a piezoelectric body provided on the lower metal electrode; and the piezoelectric body An upper metal electrode provided on the piezoelectric element, and
A control unit for controlling the piezoelectric element,
The electronic device, wherein the crystal plane orientation of the substrate is the same as the crystal plane orientation of the piezoelectric body. A single crystal substrate disposing step of providing an insulating single crystal substrate on the support film;
A lower electrode forming step of epitaxially growing a lower metal electrode on the substrate; and
A piezoelectric body forming step of epitaxially growing a piezoelectric body having the same crystal plane orientation as the substrate on the lower metal electrode;
An upper electrode forming step of forming an upper metal electrode on the piezoelectric body. A method for manufacturing a piezoelectric element. In the manufacturing method of the piezoelectric element according to claim 10,
A method of manufacturing a piezoelectric element, comprising: a thickness adjusting step of adjusting a thickness of the substrate provided on the support film. In the manufacturing method of the piezoelectric element according to claim 10 or 11,
In the step of disposing the single crystal substrate, a plurality of the substrates are provided on the support film. In the manufacturing method of the piezoelectric element according to claim 12,
An insulating film forming step of forming an insulating film on the plurality of substrates and the support film;
A thickness adjustment step of adjusting the thickness of the substrate provided on the support film,
In the thickness adjusting step, the substrate and the insulating film are polished from the opposite side to the support film to form a flat surface.

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