Freestanding film, laminated structure, element, electronic device, electronic equipment and system, and method for manufacturing piezoelectric film, electronic device and electronic equipment

Abstract

To provide an element, electronic device, electronic apparatus, and system that have excellent flexural strength and a self-supporting film and laminate structure that make it possible to obtain them in an industrially advantageous manner.SOLUTION: A self-supporting film composed of a piezoelectric film having a single layer structure is obtained by: laminating a compound film containing Hf as a first interlayer on a crystal substrate; laminating a metal film containing Fe as a second interlayer; after that, laminating a piezoelectric film just as it is or through another layer; and, after laminating the piezoelectric film, separating the crystal substrate, the first interlayer, and the second interlayer from the piezoelectric film.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a free-standing film, a laminated structure, an element, an electronic device, an electronic apparatus, and a system. [Background technology]

[0002] Piezoelectric thin films made of lead zirconate titanate (Pb(Zr,Ti)O3) (hereinafter referred to as PZT), which has excellent piezoelectric and ferroelectric properties, are being investigated, and piezoelectric thin films are being applied to memory elements such as non-volatile memory (FeRAM), and MEMS (Micro Electro Mechanical Systems) technologies such as inkjet heads and acceleration sensors.

[0003] In recent years, it has been studied to form a (200) oriented Pt film on a (100) oriented Si substrate via a (200) oriented ZrO2 film or the like, thereby forming a piezoelectric film with good piezoelectric properties on the Pt film (Patent Document 1). However, there is a problem that cracks or breaks occur in the crystal substrate or the like due to bending stress during film formation or use as a piezoelectric element, and durability and long-term use are still not satisfactory, so a piezoelectric element that is resistant to bending stress has been awaited. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2015-154015 A Summary of the Invention [Problem to be solved by the invention]

[0005] An object of the present invention is to provide an element, electronic device, electronic equipment and system having excellent bending strength, as well as a free-standing film or laminated structure from which these can be obtained in an industrially advantageous manner. [Means for solving the problem]

[0006] As a result of intensive research into achieving the above-mentioned object, the inventors have found that a piezoelectric element with excellent bending strength can be easily realized by laminating a compound film containing Hf as a first intermediate film on a crystal substrate, then laminating a metal film containing Fe as a second intermediate film, and then laminating a piezoelectric film thereon, and have found that such an element can solve the above-mentioned conventional problems in one fell swoop. After obtaining the above findings, the present inventors conducted further studies and completed the present invention.

[0007] That is, the present invention relates to the following inventions. [1] A free-standing film having a single-layer structure, characterized in that the free-standing film is a piezoelectric film. [2] The self-supporting film according to [1] above, which is flexible. [3] The free-standing film according to [1] or [2], wherein the piezoelectric film is a PTO film or a PZT film. [4] The free-standing film according to any one of [1] to [3] above, which is a single crystal film. [5] A laminated structure including at least a piezoelectric film and a metal film containing a metal as a main component, wherein the metal is a metal that undergoes martensitic transformation by heat treatment or processing. [6] The laminated structure according to [5], wherein the metal film is a metal film made of a metal that undergoes martensitic transformation by heat treatment or processing. [7] The laminate structure according to [5] or [6], wherein the metal contains Fe. [8] The layered structure according to any one of [5] to [7], wherein the metal contains Cr. [9] The stacked structure according to any one of [5] to [8], further comprising a conductive oxide film or a conductive nitride film.

[10] The laminate structure according to [9], comprising the conductive oxide film, the conductive oxide film containing Sr and / or Ru.

[11] The stacked structure according to [9] or

[10] , further comprising the conductive nitride film, the conductive nitride film containing Hf.

[12] The laminate structure according to any one of [5] to

[11] above, which has flexibility.

[13] An element including a free-standing film or a laminated structure, wherein the free-standing film is the free-standing film according to any one of [1] to [4] above, and the laminated structure is the laminated structure according to any one of [5] to

[12] above.

[14] An electronic device, electronic equipment, or system comprising a free-standing film, a laminated structure, or an element, wherein the free-standing film is the free-standing film described in any one of [1] to [4] above, the laminated structure is the laminated structure described in any one of [5] to

[12] above, and the element is the element described in

[13] above.

[15] A method for manufacturing a piezoelectric film, comprising laminating a first intermediate film on a crystal substrate, laminating a second intermediate film, and then laminating a piezoelectric film on the crystal substrate as is or via another layer, comprising the steps of: 13. A method for producing a piezoelectric film, wherein the first intermediate film is a compound film containing Hf, and the second intermediate film is a metal film containing Fe.

[16] The method according to

[15] above, further comprising the step of peeling the crystal substrate from the piezoelectric film after laminating the piezoelectric film.

[17] The method according to

[16] above, wherein the crystal substrate is peeled off by wet etching.

[18] The manufacturing method according to

[16] or

[17] , further comprising the step of peeling the first intermediate film from the piezoelectric film after peeling the crystal substrate from the piezoelectric film.

[19] The manufacturing method according to

[18] , further comprising the step of peeling off the second intermediate film from the piezoelectric film after peeling off the first intermediate film from the piezoelectric film.

[20] A method for manufacturing an electronic device or electronic equipment, comprising a step of stacking a piezoelectric film on a crystal substrate directly or via another layer, characterized in that after the piezoelectric is stacked, the crystal substrate is peeled off from the piezoelectric film. Effect of the Invention

[0008] The element, electronic device, electronic equipment and system of the present invention have excellent bending strength, and the free-standing film or laminated structure of the present invention has the effect of enabling them to be produced industrially advantageously. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 is a diagram showing a schematic diagram of an example of a preferred embodiment of a laminated structure of the present invention. [Diagram 2] FIG. 2 is a diagram showing XRD diffraction patterns in the examples. [Diagram 3] FIG. 2 is a diagram illustrating a test piece of an embodiment product in a test example. [Figure 4] FIG. 2 is a diagram illustrating a test piece of a comparative example in a test example. [Diagram 5] FIG. 13 is a diagram showing bending strength test results in a test example. [Figure 6] 1 is a diagram illustrating a preferred embodiment of a MEMS transducer according to the present invention. [Figure 7] FIG. 1 is a schematic diagram showing an example of a cross-sectional view of a portion of a wafer provided with a piezoelectric actuator, as a suitable application example of the present invention to a fluid discharge device. [Figure 8] FIG. 2 is a schematic diagram showing a film forming apparatus preferably used in the examples. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] The free-standing film of the present invention is a free-standing film having a single-layer structure, characterized in that the free-standing film is a piezoelectric film. In the present invention, it is preferable that the free-standing film is flexible. It is also preferable that the piezoelectric film is a PTO film or a PZT film. It is also preferable that the free-standing film is a single crystal film. According to such a preferable range, it is possible to provide a piezoelectric film having better piezoelectricity, particularly excellent free-standing piezoelectricity.

[0011] The laminated structure of the present invention is characterized in that it is a laminated structure including at least a piezoelectric film and a metal film containing a metal as a main component, the metal being a metal that undergoes martensitic transformation by heat treatment or processing. Note that the "main component" may be any metal whose atomic ratio in the metal film is 0.5 or more. In the present invention, the atomic ratio of the metal to all metal elements in the metal film is preferably 0.7 or more, and more preferably 0.8 or more.

[0012] The metal is not particularly limited as long as it is a metal that undergoes martensitic transformation by heat treatment or processing, and may be a known metal. Examples of the metal that undergoes martensitic transformation include Fe-Cr-Ni, Fe, Fe-Cr-Ni-Cu-Nb, Fe-Ni, Fe-Ni-Co, Fe-Si, Fe-Cr, Fe-Mn, Fe-Mn-C, Fe-Mn-Ni, Fe-Mn-Cr, Fe-C, Fe-N, Fe-Ni-C, Fe-Cr-C, Fe-Cu-C, Fe-Si-C, Fe-Cr-Ni-C, Co, Co-Ni , Co-Fe, Mn-Cu, In-Tl, In-Tl-Li, Na, Zr, Tl, Hf, Ti, Ti-Al, Ti-Cu, Ti-Cr, Ti-Fe, Ti-Mn, Ti-Mo, Ti-V, Ti-Zr, Ti-Al-V, Zr-U, Cu-Al-Ni, Cu-Al, Ag-Cd, Au-Cd, Au-Cd-Cu, Li, Li-Mg, Cu-Zn, U, U-Cr, Hg, etc. In the present invention, the metal preferably contains Fe, Cr or Ni, more preferably contains Fe and Cr, and most preferably is stainless steel. According to such a preferred range, the bending strength can be made more excellent.

[0013] In the present invention, it is preferable that the piezoelectric film and the metal film are oriented in substantially the same crystal axis direction, and it is more preferable that the piezoelectric film and the metal film are oriented in the (100) direction. The "oriented in the (100) direction" means that the crystal orientation angle detected by X-ray diffraction is oriented in the (100) direction, and more specifically, it is sufficient that the peak ratio in the (100) direction is 50% or more of the total peaks of the metal film detected by X-ray diffraction, and preferably the peak ratio is 90% or more.

[0014] In the present invention, the thickness of the metal film is preferably 100 μm or less, and more preferably 1 μm to 10 μm, which is preferable because the metal film is superior as an intermediate film for crystal growth of the functional film.

[0015] The laminated structure can be easily obtained by laminating a compound film containing Hf as a first intermediate film on a crystal substrate, then laminating a metal film containing Fe as a second intermediate film, and then laminating a piezoelectric film (hereinafter also referred to as a "piezoelectric layer") directly or via another layer. In the present invention, it is preferable to include a step of peeling the crystal substrate from the piezoelectric film after laminating the piezoelectric film. The peeling means may be any known peeling means as long as it can peel the crystal substrate from the piezoelectric film. The peeling means may be a means for removing the crystal substrate, and known removal means such as dry etching and wet etching may also be used for the peeling as long as it does not impede the object of the present invention. In the present invention, it is preferable to peel the crystal substrate by wet etching. In addition, in the present invention, it is preferable to include a step of peeling the first intermediate film from the piezoelectric film after peeling the crystal substrate from the piezoelectric film, and it is also preferable to include a step of peeling the second intermediate film from the piezoelectric film after peeling the first intermediate film from the piezoelectric film. In this way, the free-standing film can be easily obtained.

[0016] The crystal substrate (hereinafter, simply referred to as "substrate") is not particularly limited as long as the object of the present invention is not hindered, such as the substrate material, and may be a known crystal substrate. It may be an organic compound or an inorganic compound. In the present invention, it is preferable that the crystal substrate contains an inorganic compound. In the present invention, it is preferable that the substrate has crystals on a part or all of the surface, more preferably a crystal substrate having crystals on all or a part of the main surface on the crystal growth side, and most preferably a crystal substrate having crystals on the entire main surface on the crystal growth side. The crystal is not particularly limited as long as the object of the present invention is not hindered, and the crystal structure is not particularly limited, but it is preferable that it is a cubic, tetragonal, trigonal, hexagonal, orthorhombic, or monoclinic crystal, and more preferably a crystal oriented in (100) or (200). In addition, the crystal substrate may have an off angle, and examples of the off angle include an off angle of 0.2° to 12.0°. Here, the "off angle" refers to the angle between the substrate surface and the crystal growth surface. The shape of the substrate is not particularly limited as long as it is plate-like and serves as a support for the epitaxial film. It may be an insulating substrate or a semiconductor substrate, but in the present invention, the substrate is preferably a Si substrate, more preferably a crystalline Si substrate, and most preferably a crystalline Si substrate oriented in (100). In addition to the Si substrate, examples of the substrate material include one or more metals belonging to Groups 3 to 15 of the periodic table or oxides of these metals. The shape of the substrate is not particularly limited, and may be an approximately circular shape (e.g., a circular shape, an elliptical shape, etc.) or a polygonal shape (e.g., a triangular shape, a square shape, a rectangular shape, a pentagonal shape, a hexagonal shape, a heptagonal shape, an octagonal shape, a nonagonal shape, etc.), and various shapes can be suitably used. In addition, in the present invention, a large-area substrate can be used, and the area of ​​the epitaxial film can be increased by using such a large-area substrate.

[0017] In the present invention, the crystal substrate preferably has a flat surface, but it is also preferable that the crystal substrate has an uneven shape on a part or all of the surface, since this can improve the quality of the crystal growth of the epitaxial film. The crystal substrate having the uneven shape may have an uneven portion consisting of a concave or convex portion formed on a part or all of the surface, and the uneven portion is not particularly limited as long as it is composed of a convex portion or a concave portion, and may be an uneven portion consisting of a convex portion, an uneven portion consisting of a concave portion, or an uneven portion consisting of a convex portion and a concave portion. The uneven portion may be formed of regular convex portions or concave portions, or may be formed of irregular convex portions or concave portions. In the present invention, it is preferable that the uneven portion is formed periodically, and it is more preferable that the uneven portion is patterned periodically and regularly. The shape of the uneven portion is not particularly limited, and examples thereof include a stripe shape, a dot shape, a mesh shape, and a random shape, but in the present invention, a dot shape or a stripe shape is preferable, and a dot shape is more preferable. In addition, when the unevenness is patterned periodically and regularly, the pattern shape of the unevenness is preferably a polygonal shape such as a triangle, a quadrangle (for example, a square, a rectangle, or a trapezoid), a pentagon, or a hexagon, a circle, or an ellipse. In addition, when the unevenness is formed in a dot shape, the lattice shape of the dots is preferably a lattice shape such as a square lattice, an oblique lattice, a triangular lattice, or a hexagonal lattice, and more preferably a triangular lattice shape. The cross-sectional shape of the concave or convex part of the unevenness is not particularly limited, but examples thereof include a U-shape, a U-shape, an inverted U-shape, a wave shape, or a polygonal shape such as a triangle, a quadrangle (for example, a square, a rectangle, or a trapezoid), a pentagon, or a hexagon. In addition, the thickness of the crystal substrate is not particularly limited, but is preferably 50 to 2000 μm, and more preferably 100 to 1000 μm.

[0018] The piezoelectric layer is not particularly limited as long as it is a piezoelectric layer made of a piezoelectric material. The piezoelectric material may be a known piezoelectric material, but in the present invention, it is preferable that the piezoelectric material contains Pb and Ti. The semiconductor layer is not particularly limited as long as it is a semiconductor layer made of a semiconductor. The semiconductor may be a known semiconductor, but in the present invention, it is preferable that the semiconductor contains Si, SiC, GaN, or Ga2O3. In this specification, the terms "film" and "layer" may be interchangeable depending on the case or situation.

[0019] In the present invention, it is preferable that a first intermediate film is laminated on a crystal substrate, and then a second intermediate film is laminated, and then the piezoelectric layer or the semiconductor layer is laminated directly or via another layer. Examples of the other layer include a metal film, a conductive oxide film, and a conductive nitride film. In the present invention, it is preferable that the conductive oxide film contains Sr and / or Ru, and the conductive nitride film contains Hf. The metal film in the other layer is preferably made of a metal different from the metal, and examples of the metal include gold, silver, platinum, palladium, silver-palladium, copper, nickel, and alloys thereof. The above-mentioned lamination means can be laminated by using any known film forming means. In the present invention, the above-mentioned film forming means is preferably deposition (including MBE) or sputtering. The thickness of each layer is not particularly limited, but is preferably 10 nm to 100 μm, more preferably 50 nm to 30 μm.

[0020] The free-standing film or laminated structure obtained as described above can be suitably used as an element such as a piezoelectric element or a semiconductor element by using a known means. The element can also be suitably used as an electronic device according to a conventional method. For example, the laminated structure can be connected to a power source or an electric / electronic circuit as a piezoelectric element, and mounted on a circuit board or packaged to form various electronic devices. In the present invention, the electronic device is preferably a piezoelectric device, and can be used as a piezoelectric device in electronic devices such as inkjet printer heads, microactuators, gyroscopes, and motion sensors. For example, if an amplifier and a rectifier circuit are connected and packaged, the device can be used as various sensors such as magnetic sensors. The device can also be applied to constant voltage driven memories, and for example, if a storage element and a rectifier power management circuit are connected, the device can become an energy conversion device (energy harvester) that generates power from an external magnetic field or vibration. The energy conversion device is incorporated and used in a power supply system or a wearable terminal (earphone / hearable device, smart watch, smart glasses (eyeglasses), smart contact lenses, cochlear implants, cardiac pacemakers, etc.). In the present invention, the laminated structure is preferably used in, for example, smart glasses, AR headsets, MEMS mirrors for LiDAR systems, piezoelectric MEMS ultrasonic transducers (PMUTs) for advanced medical applications, and piezo heads for commercial and industrial 3D printers.

[0021] The electronic device is suitably used in electronic devices in the usual manner, and can be applied to various electronic devices other than the above-mentioned electronic devices, and more specifically, suitable examples include liquid ejection heads, liquid ejection devices, vibration wave motors, optical devices, vibration devices, imaging devices, piezoelectric acoustic parts, audio playback devices having the piezoelectric acoustic parts, audio recording devices, mobile phones, various information terminals, and the like.

[0022] Furthermore, the electronic device is also applied to a system in the usual manner, and an example of such a system is a sensor system. EXAMPLES

[0023] Example 1 The crystal growth surface of the Si substrate (100) was treated by RIE, and the metal of the deposition source was thermally reacted with nitrogen by deposition in the presence of nitrogen to form a HfZrN single crystal on the Si substrate. The deposition conditions for this film formation were as follows: Vapor deposition source: Hf, Zr Voltage: 3.5~4.75V Pressure: 3×10 -2 ~6×10 -2 Pa Substrate temperature: 450~700℃

[0024] The deposition apparatus used in the deposition of the HfZrN single crystal is shown in Fig. 8. The deposition apparatus in Fig. 8 includes at least metal sources 1101a-1101b in a crucible, earths 1102a-1102h, ICP electrodes 1103a-1103b, cut filters 1104a-1104b, DC power sources 1105a-1105b, RF power sources 1106a-1106b, lamps 1107a-1107b, Ar source 1108, reactive gas source 1109, power source 1110, substrate holder 1111, substrate 1112, cut filter 1113, ICP ring 1114, vacuum chamber 1115, and rotating shaft 1116. The ICP electrodes 1103a-1103b in Fig. 8 have a substantially concave curved shape or a parabolic shape curved toward the center of the substrate 1112.

[0025] As shown in FIG. 8, the substrate 1112 is fixed on the substrate holder 1111. Next, the rotating shaft 1116 is rotated using the power supply 1110 and a rotating mechanism (not shown) to rotate the substrate 1112. The substrate 112 is heated by the lamps 1107a-1107b, and the inside of the vacuum chamber 1115 is evacuated to a vacuum or reduced pressure by a vacuum pump (not shown). Then, Ar gas is introduced from the Ar source 1108 into the vacuum chamber 1115, and argon plasma is formed on the substrate 1112 using the DC power supplies 1105a-1105b, the RF power supplies 1106a-1106b, the ICP electrodes 1103a-1103b, the cut filters 1104a-1104b, and the earths 1102a-1102h, thereby cleaning the surface of the substrate 1112.

[0026] Ar gas is introduced into the vacuum chamber 1115, and a reactive gas is introduced using a reactive gas source 1109. At this time, lamps 1107a to 1107b, which are lamp heaters, are alternately turned on and off repeatedly, so that a crystal growth film of better quality can be formed.

[0027] Next, a SUS304 single crystal film was formed in the same manner as above, except that Fe, Cr and Ni were used as the metals of the deposition source.

[0028] Next, a platinum (Pt) metal film was formed as a conductive film on the single crystal film of the crystalline metal oxide by sputtering under the following conditions. Equipment: ULVAC sputtering equipment QAM-4 Pressure: 1.20×10 -1 Pa Target: Pt Power: 100W(DC) Thickness: 100nm Substrate temperature: 450~600℃

[0029] Next, an SRO film was formed on the conductive film by sputtering under the following conditions. Equipment: ULVAC sputtering equipment QAM-4 Power: 150W(RF) Gas: Ar Pressure: 1.8Pa Substrate temperature: 600℃ Thickness: 20nm

[0030] Next, a PbTiO3 film was formed as a piezoelectric film on the SRO film. The resulting laminated structure had good adhesion and crystallinity. In addition, the crystallinity of the crystalline substrate of the laminated structure, the single crystal film of the crystalline metal oxide, and the conductive film were measured using an X-ray diffraction device. Figure 2 shows the results of the XRD measurement. As is clear from Figure 2, a SUS304 single crystal film with good crystallinity was formed, and the crystallinity of the PbTiO3 film and other films was also good.

[0031] After forming the PbTiO3 film, the Si substrate was removed by wet etching using sodium hydroxide, and the Si substrate was peeled off from the PbTiO3 film. The HfZrN film, Pt film, and SRO film were each removed by wet etching using HF, and each was peeled off from the PbTiO3 film. The obtained free-standing film was a single crystal film and had flexibility.

[0032] (Test Example) As a test example, a cantilever beam of a microelement as shown in Figures 3 and 4 was fabricated using FIB FB2100 (Hitachi High-Technologies), and its fracture strength characteristics were evaluated using a nanoindenter NanoTest Xtreme (Micro Materials), as shown in Figure 5. Figure 5 shows that the fracture strength of Si was approximately 1 GPa, which was a nearly constant value. Considering that the bending strength of Si single crystal bulk material is approximately 300 MPa (paper), it was found that micromaterials have great strength. Furthermore, in the case of SUS304 single crystal thin film, the fracture strength was approximately 5 GPa, which is approximately 5 times the bending strength of Si single crystal. This means that by using SUS304 single crystal thin film for the beam of a MEMS device (movable part, equivalent to the active layer of an SOI substrate), it is expected that the displacement amount of the MEMS device will be significantly improved, as well as the life characteristics will be significantly improved.

[0033] (Examples) Examples of applications of the obtained laminated structure will be described in more detail below with reference to the drawings, but the present invention is not limited to these examples. In the present invention, unless otherwise specified, a piezoelectric device or the like can be manufactured from the laminated structure by using known means.

[0034] 6 shows an embodiment of an acoustic MEMS transducer constituting a MEMS microphone in which the laminate structure of the present invention is preferably used. The MEMS transducer can constitute an acoustic emission device (e.g., a speaker, etc.).

[0035] The MEMS microphone configured with the acoustic MEMS transducer of FIG. 6 shows a cantilever type MEMS microphone, and includes a Si substrate 21 having two cantilever beams 28A, 28B and a cavity 30. Each of the cantilever beams 28A, 28B is fixed to the substrate 21 at each end, and a gap 9 is provided between the cantilever beams 8A, 8B. The cantilever beams 8A, 8B are formed, for example, by a laminated structure including a plurality of piezoelectric layers (PZT films) 26a, 26b, and are alternated with a plurality of electrode layers, i.e., Pt films 24a, 24b, 24c and SRO films 25a, 25b, 25c, 25d. The Pt film 24a is provided on a SUS film 23, and the HfZrN film 23 is provided on the SUS film 23. Compared with the case of using SiO2, SiN, etc., the use of the HfZrN film 23 provides excellent adhesion and crystallinity with the Si substrate, and the crystallinity can be further improved up to the multiple layers thereon, and further provides excellent piezoelectric properties and durability.

[0036] FIG. 7 shows an example of application of the laminated structure of the present invention to a printing application, particularly to a fluid discharge device that can be used in the form of an inkjet printhead, and specifically shows a cross-sectional view of a portion of a wafer having a piezoelectric actuator including Pt films 34a, 34b and SRO films 35a, 35b as electrode layers and a PZT film 36 as a piezoelectric film. The wafer of FIG. 7 has a chamber 41 for containing a fluid in addition to the piezoelectric actuator. The chamber 41 is configured to take in a fluid from a tank (not shown) through a flow path 40. The wafer of FIG. 10 includes a Si substrate 31, on which a HfZrN film 32 and a SUS film 33 are laminated, facing the chamber 41. In FIG. 10, the HfZrN film 32 is used, which provides better adhesion and crystallinity with the Si substrate than when SiO2, SiN, or the like is used, and the crystallinity is further improved up to a plurality of layers thereon, and further provides better piezoelectric properties and durability. The HfZrN film 32 has, for example, a quadrangular shape in a top view (not shown), and this shape may be, for example, any of a square, a rectangle, a rectangle with rounded corners, a parallelogram, and the like.

[0037] On the SUS film 33, a Pt film 34a, an SRO film 35a, a piezoelectric film (PZT film) 36, an SRO film 35b, and a Pt film 34b are laminated in this order to form a piezoelectric actuator. The piezoelectric actuator further includes an insulating film 37 extending on the electrodes 34a and 35a, the piezoelectric film 36, and the electrodes 34b and 35b. The insulating film 37 includes a dielectric material used for electrical insulation, and such a dielectric material may be a known dielectric material, for example, a SiO2 layer, a SiN layer, or an Al2O3 layer. The thickness of the insulating layer including the insulating film as a constituent material is not particularly limited, but is preferably between about 10 nm and about 10 μm. The conductive path 39 is provided on the insulating layer (insulating film) 37 and contacts the electrodes 34a and 35a and the electrodes 34b and 35b, respectively, to enable selective access during use. The conductive path may be made of a known conductive material, and a suitable example of such a conductive material is aluminum (Al). The passivation layer 42 is provided on the insulating layer 37, the electrodes 34b and 35b, and the conductive path 39. The passivation layer 42 may be made of a dielectric material used for passivation of the piezoelectric actuator, and the dielectric material is not particularly limited and may be a known dielectric material. Suitable examples of the dielectric material include SiN and SiON (silicon oxynitrate). The thickness of the passivation layer is not particularly limited, but is preferably between about 0.1 μm and about 3 μm. The conductive pad 38 is also provided along the piezoelectric actuator and is electrically connected to the conductive path 39. The passivation layer 42 functions as a barrier layer that protects the piezoelectric body from moisture and the like. [Industrial Applicability]

[0038] The free-standing film and laminated structure of the present invention are suitable for use as electronic devices such as piezoelectric devices, and are suitable for use in electronic equipment, sensor systems, and the like. [Explanation of symbols]

[0039] 1 Crystalline substrate (Si substrate) 2 HfZrN film 3 SUS membrane (FeCrNi membrane) 4 Pt membrane 5 SRO membrane 6 Piezoelectric layer (PbTiO film) 21 Crystalline substrate (Si substrate) 22 HfZrN film 23 SUS membrane 24a Pt membrane 24b Pt membrane 24c Pt membrane 25a SRO membrane 25b SRO membrane 25c SRO membrane 25d SRO membrane 26a PZT membrane 26b PZT membrane 28A Cantilever Beam 28B Cantilever beam 29 Gap 30 cavities 31 Crystalline substrate (Si substrate) 32 HfZrN film 33 SUS membrane 34a Pt membrane 34b Pt membrane 35a SRO membrane 35b SRO membrane 36 PZT membrane 37 Insulating Film 38 Conductive Pad 39 Conductive Path 40 Flow Path 41 Chamber 42 Passivation Layer 1101a~101b Metal source 1102a~102j Earth 1103a~103b ICP electrode 1104a~104b Cut Filter 1105a~105b DC power supply 1106a~106b RF power supply 1107a~107b Lamp 1108 Ar source 1109 Reactive Gas Source 1110 Power supply 1111 PCB holder 1112 Substrate 1113 Cut Filter 1114 ICP Ring 1115 Vacuum chamber 1116 Rotating shaft

Claims

1. A free-standing film having a single-layer structure, characterized in that the free-standing film is a piezoelectric film.

2. 2. The free-standing membrane of claim 1, which is flexible.

3. 3. The free-standing film according to claim 1, wherein the piezoelectric film is a PTO film or a PZT film.

4. 3. The free-standing film according to claim 1, which is a single crystal film.

5. A laminated structure comprising at least a piezoelectric film and a metal film containing a metal as a main component, wherein the metal is a metal that undergoes martensitic transformation upon heat treatment or processing.

6. 6. The laminated structure according to claim 5, wherein the metal film is made of a metal that undergoes martensitic transformation upon heat treatment or processing.

7. The laminated structure according to claim 5 or 6, wherein the metal includes Fe.

8. The laminated structure according to claim 5 or 6, wherein the metal includes Cr.

9. 7. The laminated structure according to claim 5, further comprising a conductive oxide film or a conductive nitride film.

10. The laminated structure according to claim 9 , comprising the conductive oxide film, the conductive oxide film containing Sr and / or Ru.

11. The stacked structure according to claim 9 , comprising the conductive nitride film, the conductive nitride film containing Hf.

12. The laminated structure according to claim 5 or 6, which has flexibility.

13. 7. A device comprising a free-standing film or a laminated structure, wherein the free-standing film is the free-standing film according to claim 1 or 2, and the laminated structure is the laminated structure according to claim 5 or 6.

14. An electronic device, electronic equipment, or system comprising a free-standing film or a laminated structure, wherein the free-standing film is the free-standing film according to claim 1 or 2, and the laminated structure is the laminated structure according to claim 5 or 6.

15. A method for manufacturing a piezoelectric film, comprising laminating a first intermediate film on a crystal substrate, then laminating a second intermediate film, and then laminating a piezoelectric film on the first intermediate film or the second intermediate film with another layer interposed therebetween, A method for manufacturing a piezoelectric film, wherein the first intermediate film is a compound film containing Hf, and the second intermediate film is a metal film containing Fe.

16. The method for manufacturing a piezoelectric film according to claim 15, further comprising the step of peeling off the crystal substrate from the piezoelectric film after laminating the piezoelectric film.

17. The method for producing a piezoelectric film according to claim 16, wherein the crystal substrate is peeled off by wet etching.

18. The method for manufacturing a piezoelectric film according to claim 16 or 17, further comprising the step of peeling off the first intermediate film from the piezoelectric film after peeling off the crystal substrate from the piezoelectric film.

19. 19. The method for manufacturing a piezoelectric film according to claim 18, further comprising the step of peeling off the second intermediate film from the piezoelectric film after peeling off the first intermediate film from the piezoelectric film.

20. A method for manufacturing an electronic device or electronic equipment, comprising a step of stacking a piezoelectric film on a crystal substrate directly or via another layer, characterized in that after the piezoelectric film is stacked, the crystal substrate is peeled off from the piezoelectric film.

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