Manufacturing method of piezoelectric film bonded substrate

Abstract

To provide a high-performance piezoelectric-body film joint substrate in which piezoelectric films of two or more types are provided on the same substrate, and a manufacturing method thereof.SOLUTION: A piezoelectric-body film joint substrate (100) includes a substrate (33), a first electrode (34a), a first piezoelectric-body film (17) stuck on the first electrode and including a first piezoelectric film (15) and a first upper electrode film (16) formed on the first piezoelectric film, a second electrode (34b), and a second piezoelectric-body film (27) stuck on the second electrode and including a second piezoelectric film (25) different from the first piezoelectric film (15) and a second upper electrode film (26) formed on the second piezoelectric film. A height from an upper surface of the substrate (33), on which the first electrode (34a) and the second electrode (34b) are formed, to a top of the first upper electrode film (16) and a height from the upper surface of the substrate (33) to a top of the second upper electrode film (26) differ from each other.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a piezoelectric film-bonded substrate and a method for manufacturing the same. [Background technology]

[0002] Conventionally, there has been disclosed an ultrasonic sensor that is formed as a piezoelectric film integrated device by forming different types of polycrystalline piezoelectric films on the same substrate (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2021-166220 Summary of the Invention [Problem to be solved by the invention]

[0004] However, when a plurality of different types of piezoelectric films are formed on the same substrate, it is not possible to obtain a high-performance device having a plurality of piezoelectric films.

[0005] An object of the present disclosure is to provide a high-performance piezoelectric film bonded substrate in which two or more types of piezoelectric films are provided on the same substrate, and a method for manufacturing the same. [Means for solving the problem]

[0007] The method for manufacturing a piezoelectric film bonded substrate disclosed herein is a method for manufacturing a piezoelectric film bonded substrate having a device substrate and a first piezoelectric film and a second piezoelectric film having different film thicknesses, and is characterized by: peeling the first piezoelectric film formed on the first substrate and the second piezoelectric film formed on the second substrate from the first substrate and the second piezoelectric film formed on the second substrate, respectively; when the piezoelectric film having the thinner film thickness of the first piezoelectric film and the second piezoelectric film is designated as a first film thickness and the piezoelectric film having the thicker film thickness is designated as a second film thickness, the film having the first film thickness is attached to a first electrode formed on the device substrate; and after the film having the first film thickness is attached, the film having the second film thickness is attached to a second electrode formed on the device substrate.

[0008] Another method for manufacturing a piezoelectric film bonded substrate according to the present disclosure is a method for manufacturing a piezoelectric film bonded substrate having a device substrate having a first electrode and a second electrode with different film thicknesses, a first piezoelectric film, and a second piezoelectric film, the method comprising the steps of peeling the first piezoelectric film formed on the first substrate and the second piezoelectric film formed on the second substrate from the first substrate and the second substrate, respectively, and, when the electrode with the thicker film thickness of the first electrode and the second electrode is designated as the electrode with the first film thickness and the electrode with the thinner film thickness is designated as the electrode with the second film thickness, bonding the second piezoelectric film to the electrode with the second film thickness formed on the device substrate, and, after the film with the second film thickness has been bonded, bonding the first piezoelectric film to the first electrode. [Effects of the Invention]

[0009] According to the present disclosure, it is possible to provide a high-performance piezoelectric film bonded substrate in which two or more types of piezoelectric films are provided on the same substrate, and a method for manufacturing the same. [Brief explanation of the drawings]

[0010] [Figure 1]1 is a side view schematically showing the structure of a piezoelectric film bonded substrate according to Embodiment 1. FIG. [Figure 2] FIG. 2 is a top view schematically showing the structure of the piezoelectric film bonded substrate of FIG. [Figure 3] 3 is a cross-sectional view of the piezoelectric film bonded substrate taken along line S3-S3 in FIG. 2. [Figure 4] 3 is a flowchart showing a method for manufacturing a piezoelectric film bonded substrate according to the first embodiment. [Figure 5] 4A and 4B are a top view and a cross-sectional view schematically showing the structure of a PZT epitaxially grown film in step ST101 of FIG. 4, and FIG. 4C and 4D are a top view and a cross-sectional view schematically showing the structure of multiple PZT piezoelectric films in step ST102 of FIG. 4. [Figure 6] (A) and (B) are a top view and a cross-sectional view schematically showing the structure of an AlN epitaxially grown film in step ST104 of Figure 4, and (C) and (D) are a top view and a cross-sectional view schematically showing the structure of multiple AlN piezoelectric films in step ST105 of Figure 4. [Figure 7] 5(A) and 5(B) are cross-sectional views schematically showing the process of holding a plurality of PZT piezoelectric films in step ST103 of FIG. [Figure 8] 5(A) and 5(B) are cross-sectional views schematically showing the process of holding a plurality of AlN piezoelectric films in step ST106 of FIG. [Figure 9] 4. (A) is a cross-sectional view that schematically shows the process of attaching the AlN piezoelectric film in step ST107 of FIG. 4, and (B) is a top view that shows the state in which the AlN piezoelectric film has been attached. [Figure 10] 4. (A) is a cross-sectional view that schematically shows the process of attaching the PZT piezoelectric film in step ST108 of FIG. 4, and (B) is a top view that shows the state in which the PZT piezoelectric film has been attached. [Figure 11]4. (A) is a cross-sectional view that schematically shows the process of attaching another PZT piezoelectric film in step ST108 of FIG. 4, and (B) is a top view that shows the state in which another PZT piezoelectric film has been attached. [Figure 12] 10(A) and 10(B) are a side view and a top view schematically showing the structure of a piezoelectric film bonded substrate according to a modified example of the first embodiment. [Figure 13] (A) and (B) are a cross-sectional view and a top view schematically showing the structure of an AlN piezoelectric film according to a modified example of embodiment 1, and (C) and (D) are a cross-sectional view and a top view schematically showing the structure of a PZT piezoelectric film. [Figure 14] 1A and 1B are a side view and a top view schematically showing the structure of a piezoelectric film bonded substrate according to Embodiment 1. FIG. [Figure 15] 10 is a flowchart showing a method for manufacturing a piezoelectric film bonded substrate according to the second embodiment. [Figure 16] FIG. 1 is a cross-sectional view schematically showing the structure of an epitaxially grown film including a PZT piezoelectric film. [Figure 17] FIG. 1 is a cross-sectional view schematically illustrating the structure of an epitaxially grown film including an AlN piezoelectric film. [Figure 18] 15. (A) is a cross-sectional view that schematically shows the process of attaching the AlN piezoelectric film in step ST207 of FIG. 15, and (B) is a top view that shows the state in which the AlN piezoelectric film has been attached. [Figure 19] 15. (A) is a cross-sectional view that schematically shows the process of attaching the PZT piezoelectric film in step ST208 of FIG. 15, and (B) is a top view that shows the state in which the PZT piezoelectric film has been attached. [Figure 20] 10A is a cross-sectional view that schematically shows the process of attaching another PZT piezoelectric film, and FIG. 10B is a top view that shows the state in which another PZT piezoelectric film has been attached. [Figure 21] 10(A) and 10(B) are a side view and a top view schematically showing the structure of a piezoelectric film bonded substrate according to Embodiment 3. FIG. [Figure 22] 10 is a flowchart showing a method for manufacturing a piezoelectric film bonded substrate according to the third embodiment. [Figure 23] FIG. 1 is a cross-sectional view schematically showing the structure of an epitaxially grown film including a PZT piezoelectric film. [Figure 24] FIG. 1 is a cross-sectional view schematically illustrating the structure of an epitaxially grown film including an AlN piezoelectric film. [Figure 25] (A) and (B) are a cross-sectional view and a top view schematically showing the structure of the PZT piezoelectric film in step ST301 of Figure 22, and (C) and (D) are a cross-sectional view and a top view schematically showing the structure of the PZT piezoelectric film in step ST302 of Figure 22. [Figure 26] (A) and (B) are a cross-sectional view and a top view schematically showing the structure of an AlN piezoelectric film in step ST304 of Figure 22, and (C) and (D) are a cross-sectional view and a top view schematically showing the structure of an AlZ piezoelectric film in step ST305 of Figure 22. [Figure 27] 23(A) and 23(B) are cross-sectional views schematically showing the process of holding a plurality of PZT piezoelectric films in step ST303 of FIG. 22. [Figure 28] 23(A) and 23(B) are cross-sectional views schematically illustrating the process of holding a plurality of AlN piezoelectric films in step ST306 of FIG. [Figure 29] 22. (A) is a cross-sectional view that schematically shows the process of attaching the AlN piezoelectric film in step ST307 of FIG. 22, and (B) is a top view that shows the state in which the AlN piezoelectric film has been attached. [Figure 30] 22. (A) is a cross-sectional view that schematically shows the process of attaching the PZT piezoelectric film in step ST308 of FIG. 22, and (B) is a top view that shows the state in which the PZT piezoelectric film has been attached. [Figure 31] 22. (A) is a cross-sectional view that schematically shows the process of attaching another PZT piezoelectric film in step ST308 of FIG. 22, and (B) is a top view that shows the state in which another PZT piezoelectric film has been attached. DETAILED DESCRIPTION OF THE INVENTION

[0011] Piezoelectric film-bonded substrates and manufacturing methods thereof according to embodiments will be described below with reference to the drawings. The following embodiments are merely examples, and various modifications are possible within the scope of this disclosure. In this application, the piezoelectric film-bonded substrate is an intermediate product in which multiple piezoelectric films are provided on the same substrate. The piezoelectric films are preferably single-crystal piezoelectric films, but can also be polycrystalline piezoelectric films.

[0012] By using the piezoelectric film bonded substrate according to the embodiment, a piezoelectric film integrated device having a plurality of piezoelectric bodies can be manufactured. This piezoelectric film integrated device is, for example, an acoustic vibration sensor. An acoustic vibration sensor is a sensor that outputs an acoustic vibration wave and detects the reflected wave of the acoustic vibration wave to detect the state (e.g., distance, shape, movement, etc.) of an object to be detected. An acoustic vibration sensor is also called an "ultrasonic sensor." Generally, and in this application, an acoustic vibration wave is composed of at least one of a sound wave and an ultrasonic wave. That is, an acoustic vibration wave is composed of a sound wave, an ultrasonic wave, or both a sound wave and an ultrasonic wave.

[0013] 1. First embodiment <1-1> Structure of the piezoelectric film bonded substrate 100 Fig. 1 is a side view schematically showing the structure of a piezoelectric film bonded substrate 100 according to embodiment 1. Fig. 2 is a top view schematically showing the structure of the piezoelectric film bonded substrate 100. Fig. 3 is a cross-sectional view of the piezoelectric film bonded substrate 100 of Fig. 2 taken along line S3-S3.

[0014] The piezoelectric film bonded substrate 100 has an SOI substrate 33 as a substrate, and platinum (Pt) films 34a and 34b as electrodes (i.e., substrate electrodes) provided on the SOI substrate 33. As shown in FIG. 2, the Pt films 34a and 34b are connected to a wiring layer formed on the SOI substrate 33. SOI stands for silicon on insulator. Also, a drive circuit for driving the piezoelectric film bonded substrate 100 to generate acoustic vibration waves, a processing circuit for performing processing using detection signals of the acoustic vibration waves, and the like may be formed within the SOI substrate 33.

[0015] The piezoelectric film bonded substrate 100 includes a Pt film 34a serving as a first electrode (substrate electrode) on an SOI substrate 33, a PZT piezoelectric film 17 serving as a first piezoelectric film bonded to the Pt film 34a, a Pt film 34b serving as a second electrode (substrate electrode) on the SOI substrate 33, and an AlN piezoelectric film 27 serving as a second piezoelectric film bonded to the Pt film 34b. The PZT piezoelectric film 17 includes a PZT film 15 serving as a first piezoelectric film and a Pt film 16 formed thereon as a first upper electrode film, and is bonded to the Pt film 34a. The AlN piezoelectric film 27 includes an AlN film 25 serving as a second piezoelectric film different from the first piezoelectric film (e.g., having a different crystal structure) and a Pt film 26 formed thereon as a second upper electrode film, and is bonded to the Pt film 34b. In the first embodiment, the height (H1 in FIG. 3) from the upper surface of the SOI substrate 33 on which the Pt films 34a and 34b are formed to the top of the Pt film 16 is different from the height (H2 in FIG. 3) from the upper surface of the SOI substrate 33 to the top of the Pt film 26. In the first embodiment, there is a relationship of H1>H2.

[0016] AlN is aluminum nitride. PZT is lead zirconate titanate. Instead of the AlN piezoelectric film, other piezoelectric films such as lithium tantalate (LiTaO) or lithium niobate (LiNbO) may be used as the first piezoelectric film. Instead of the PZT piezoelectric film, other piezoelectric films such as potassium sodium niobate (KNN) or barium titanate (BaTiO) may be used as the second piezoelectric film. The first and second piezoelectric films are preferably single-crystal piezoelectric films, but may also be polycrystalline piezoelectric films. In the illustrated example, the PZT piezoelectric film 17 is a piezoelectric that generates acoustic vibration waves. It is desirable that the PZT piezoelectric film 17 has a larger piezoelectric constant than the vibration amplitude of the AlN piezoelectric film 27, thereby achieving a large vibration amplitude. The AlN piezoelectric film 27 is a piezoelectric that detects acoustic vibration waves (or their reflected waves). It has a lower dielectric constant than the PZT piezoelectric film 17 and therefore higher detection sensitivity.

[0017] It is also possible to use an AlN piezoelectric film 27 as the first piezoelectric film and a PZT piezoelectric film 17 as the second piezoelectric film.

[0018] As shown in FIG. 1, the piezoelectric film bonded substrate 100 has an insulating film 35a and a wiring film 36a formed thereon, an insulating film 35b and a wiring film 36b formed thereon.

[0019] The SOI substrate 33 includes a Si substrate 30, a silicon oxide (SiO2) portion 31 as an insulating film, and a single-crystal silicon (single-crystal Si) portion 32. A cavity may be formed in the Si substrate 30 by etching the Si substrate 30 in the region of the single-crystal Si portion 32 below the PZT film 15 and the AlN film 25 (i.e., the region overlapping the piezoelectric film). The SiO2 portion 31 and the single-crystal Si portion 32 located in the region where the cavity is formed function as a diaphragm. Alternatively, a substrate made of other materials, such as a glass substrate or an organic film substrate, may be used instead of the SOI substrate 33. Acoustic vibration waves generated in the PZT film 15 are output from the cavity, and the AlN film 25 detects the reflected acoustic vibration waves through the cavity.

[0020] The thickness of the PZT film 15 is generally in the range of 10 nm to 10 μm, preferably in the range of 100 nm to 5 μm. The thickness of the AlN film 25 is generally in the range of 10 nm to 10 μm, preferably in the range of 100 nm to 2 μm. The Pt films 34a and 34b are formed on the upper surface of the SOI substrate 33. The surface (upper surface) of the Pt film 34b and the AlN piezoelectric film 27 are bonded by intermolecular forces. The surface of the Pt film 34a and the PZT piezoelectric film 17 are bonded by intermolecular forces. No adhesive is required for these bonds. To bond these films well by intermolecular forces, it is desirable that the surface roughness of the bonding surfaces of the AlN piezoelectric film 27, the bonding surfaces of the PZT piezoelectric film 17, and the Pt films 34a and 34b be 10 nm or less. For this purpose, the surfaces of the Pt films 34a and 34b may be smoothed. Furthermore, the surface roughness of the interface between the bonding surface of the PZT piezoelectric film 17 and the bonding surface of the AlN piezoelectric film 27 when they are bonded to the Pt films 34a, 34b, respectively, is 10 nm or less. Furthermore, the surface area of ​​the Pt film 34a is desirably larger than the surface area of ​​the bonding surface of the PZT piezoelectric film 17, and the surface area of ​​the Pt film 34b is desirably larger than the surface area of ​​the bonding surface of the AlN piezoelectric film 27. This structure allows for a larger tolerance for error in bonding accuracy when bonding the AlN piezoelectric film 27 and the PZT piezoelectric film 17 to the Pt films 34b, 34a.

[0021] 《1-2》Manufacturing method In manufacturing the piezoelectric film bonded substrate 100, a PZT piezoelectric film 17 formed on the growth substrate 11 and having a PZT film 15 and a Pt film 16 disposed thereon, and an AlN piezoelectric film 27 formed on the growth substrate 21 and having an AlN film 25 and a Pt film 26 disposed thereon, are peeled off from the growth substrates 11 and 21, respectively, and the PZT piezoelectric film 17 is bonded to a Pt film 34a, which is an electrode formed on an SOI substrate 33 that is different from either of the growth substrates 11 and 21, and the AlN piezoelectric film 27 is bonded to a Pt film 34b.

[0022] FIG. 4 is a flowchart showing a method for manufacturing a piezoelectric film bonded substrate 100. FIGS. 5(A) and 5(B) are a top view and a cross-sectional view, respectively, schematically showing the structure of a PZT epitaxially grown film in step ST101 of FIG. 4. FIGS. 5(C) and 5(D) are a top view and a cross-sectional view, respectively, schematically showing the structure of a PZT epitaxially grown film in step ST102 of FIG. 4. FIGS. 6(A) and 6(B) are a top view and a cross-sectional view, respectively, schematically showing the structure of an AlN epitaxially grown film in step ST104 of FIG. 4. FIGS. 6(C) and 6(D) are a top view and a cross-sectional view, respectively, schematically showing the structure of an AlN epitaxially grown film in step ST105 of FIG. 4. FIGS. 7(A) and 7(B) are cross-sectional views schematically showing the holding process of a plurality of PZT piezoelectric films 17 in step ST103 of FIG. 4. 8(A) and 8(B) are cross-sectional views schematically showing the process of holding a plurality of AlN piezoelectric films 27 in step ST106 of FIG. 4. FIG. 11(A) is a cross-sectional view schematically showing the process of bonding the AlN piezoelectric films 27 in step ST107 of FIG. 4, and FIG. 11(B) is a top view showing the state where the AlN piezoelectric films 27 have been bonded. FIG. 10(A) is a cross-sectional view schematically showing the process of bonding the PZT piezoelectric films 17 in step ST108 of FIG. 4, and FIG. 10(B) is a top view showing the state where the PZT piezoelectric films 17 have been bonded. FIG. 11(A) is a cross-sectional view showing the next manufacturing process of a piezoelectric film bonded substrate, and FIG. 11(B) is a top view showing the state where the PZT piezoelectric films 17 have been bonded.

[0023] First, as shown in Figures 5(A) and (B), a sacrificial layer 14, a PZT film 15, and a Pt film 16 are epitaxially grown on a growth substrate (step ST101), and as shown in Figures 5(C) and (D), the PZT film 15 and the Pt film 16 are etched into circular shapes to form a plurality of PZT piezoelectric films 17 (step ST102).

[0024] 6(A) and (B), a sacrificial layer 24, an AlN film 25, and a Pt film 26 are epitaxially grown on another growth substrate (step ST104), and as shown in FIGS. 6(C) and (D), the AlN film 25 and the Pt film 26 are etched into circular shapes to form multiple AlN piezoelectric films 27 (step ST105).

[0025] 9(A) and 9(B), a plurality of (four in the illustrated example) PZT piezoelectric films 17, each consisting of a PZT film 15 and a Pt film 16, are held by a stamp 42 as a holding member, and are peeled off by etching the sacrificial layer (step ST103). Also, as shown in FIGS. 8(A) and 8(B), a plurality of (four in the illustrated example) AlN piezoelectric films 27, each consisting of an AlN film 25 and a Pt film 26, are held by a stamp 41 as a holding member, and are peeled off by etching the sacrificial layer (step ST106).

[0026] Next, as shown in FIGS. 11A and 11B, one of the plurality of AlN piezoelectric films 27 held by the stamp 41 is attached onto the Pt film 34b (step ST107).

[0027] 10(A) and 10(B), one of the multiple PZT piezoelectric films 17 held by the stamp 42 is attached to the Pt film 26 of the AlN piezoelectric film 27 attached to the Pt film 34 (step ST108). After attachment, an annealing process may be added to strengthen the attachment between the Pt and the piezoelectric film.

[0028] As shown in FIGS. 11A and 11B, in the first embodiment, contact electrodes and wiring patterns are formed on an SOI substrate 33 using Pt. An AlN piezoelectric film 27 is then attached to the Pt film 34b, and a PZT piezoelectric film 17 is then attached to the Pt film 34a. When the AlN piezoelectric film 27 held by the stamp 41 is in a 2x2 matrix, it is attached to different SOI substrates 33 in the order of #1, #2, #3, and #4 in the figure. In this example, four SOI substrates 33 are prepared for four piezoelectric films. Next, as shown in FIGS. 10A and 10B, a PZT piezoelectric film 17 is attached to the Pt film 34a. When the PZT piezoelectric film 17 held by the stamp 42 is in a 2x2 matrix, it is attached to different SOI substrates 33 in the order of #1, #2, #3, and #4 in the figure. The sequential attachment is performed as shown in FIGS. 10A and 10B. In this case, since the height H2 of the top of the AlN piezoelectric film 27 is lower than the height H1 of the top of the PZT piezoelectric film 17, as shown in Figure 11(A), the portion 42a of the stamp 42 does not come into contact with the AlN piezoelectric film 27 attached to the Pt film 34b.

[0029] Next, an insulating film 35a and a wiring film 36a are formed on the PZT film 15 and the Pt film 16, and an insulating film 35b and a wiring film 36b are formed on the AlN film 25 and the Pt film 26.

[0030] When bonding, the efficiency of the piezoelectric vibration driving of the PZT film 15 and the piezoelectric vibration receiving of the AlN film 25 is maximized by arranging the hexagonal crystal of AlN and the cubic crystal of PZT so that the c-axes are parallel to each other.

[0031] 1-3 Variations 12(A) and 12(B) are a side view and a top view, respectively, schematically showing the structure of a piezoelectric film bonded substrate 100a according to a modified example of Embodiment 1. FIGS. 13(A) and 13(B) are a top view and a cross-sectional view, respectively, schematically showing the structure of an AlN piezoelectric film 27, and FIGS. 13(C) and 13(D) are a top view and a cross-sectional view, respectively, schematically showing the structure of a PZT piezoelectric film 17. The piezoelectric film bonded substrate 100a differs from the piezoelectric film bonded substrate 100 shown in FIGS. 1 to 3 in that the AlN piezoelectric film 27 and the PZT piezoelectric film 17 have rectangular planar shapes. Apart from this, the piezoelectric film bonded substrate 100a is the same as the piezoelectric film bonded substrate 100.

[0032] Effect 1-4 As explained above, in the first embodiment, the PZT piezoelectric film 17 and the AlN piezoelectric film 27, which are difficult to epitaxially grow on the same SOI substrate 33 due to their different lattice constants and crystal structures, are formed on separate growth substrates, peeled from the growth substrates, and then laminated on the common SOI substrate 33, thereby making it possible to create a high-performance piezoelectric film bonded substrate 100. Furthermore, by bonding the piezoelectric film onto the substrate, it is possible to manufacture a piezoelectric film bonded substrate without residual stress distortion.

[0033] Furthermore, the single-crystal PZT film 15 has a higher piezoelectric constant than a polycrystalline PZT film, making it easy to increase the amplitude of vibration. Furthermore, the single-crystal AlN film 25 has a lower dielectric constant than a polycrystalline AlN film, making it possible to increase the vibration reception sensitivity. However, the PZT film 15 may contain polycrystalline PZT, and the AlN film 25 may contain polycrystalline AlN. In other words, the single-crystallization rates of the PZT film 15 and the AlN film 25 may be 100% or less.

[0034] Furthermore, in embodiment 1, the height H2 of the top of the AlN piezoelectric film 27 is lower than the height H1 of the top of the PZT piezoelectric film 17, so that the lower surface of the stamp 42 and other parts do not come into contact with the AlN piezoelectric film 27 attached to the Pt film 34b.

[0035] Furthermore, conventionally, forming heterogeneous piezoelectric films required complex processes such as covering one piezoelectric film with a protective layer and then removing the protective layer after forming the other piezoelectric film, and the application of heat during each process left residual stress strain in the piezoelectric film, resulting in a decrease in efficiency as a sensor.However, the manufacturing method of embodiment 1 makes it possible to form a piezoelectric film bonded substrate and an acoustic vibration sensor without residual stress strain.

[0036] 2. Second Embodiment 2-1 Structure of the piezoelectric film bonded substrate 200 14(A) and 14(B) are a side view and a top view schematically showing the structure of a piezoelectric film bonded substrate 200 according to embodiment 2. In Fig. 14(A) and 14(B), components that are the same as or correspond to those shown in Fig. 1 to Fig. 3 are assigned the same reference numerals as those shown in Fig. 1 to Fig. 3.

[0037] The piezoelectric film bonded substrate 200 includes a Pt film 134a serving as a substrate electrode provided on an SOI substrate 33, a PZT piezoelectric film 17 bonded to the Pt film 134a, a Pt film 34b serving as a substrate electrode provided on the SOI substrate 33, and an AlN piezoelectric film 27 bonded to the Pt film 34b. The PZT piezoelectric film 17 includes a PZT film 15 and a Pt film 16 formed thereon, with the PZT film 15 bonded to the Pt film 134a. The AlN piezoelectric film 27 includes an AlN film 25 and a Pt film 26 formed thereon, with the AlN film 25 bonded to the Pt film 34b. In the first embodiment, the thickness t134 of the Pt film 134a is greater than the thickness t34 of the Pt film 34b. In the second embodiment, a height H1 from the upper surface of the SOI substrate 33 on which the Pt films 134a and 34b are formed to the top of the Pt film 16 is different from a height H2 from the upper surface of the SOI substrate 33 to the top of the Pt film 26. In the second embodiment, there is a relationship of H1>H2. Except for the above, the structure of the piezoelectric film bonded substrate 200 is the same as that of the piezoelectric film bonded substrate 100.

[0038] 《2-2》Manufacturing method FIG. 15 is a flowchart illustrating a method for manufacturing a piezoelectric film bonded substrate 200. FIG. 16 is a cross-sectional view schematically illustrating the structure of an epitaxially grown film including a PZT piezoelectric film 17. FIG. 17 is a cross-sectional view schematically illustrating the structure of an epitaxially grown film including an AlN piezoelectric film 27. As shown in FIGS. 16 and 17, in the second embodiment, the thickness (t11=t12+t13) of the PZT piezoelectric film 17 used is equal to the thickness (t11=t12+t13) of the AlN piezoelectric film 27. However, since the thickness t134 of the Pt film 134a is greater than the thickness t34 of the Pt film 34b (i.e., t134>t34), the height H1 from the upper surface of the SOI substrate 33 to the top of the Pt film 16 can be greater than the height H2 from the upper surface of the SOI substrate 33 to the top of the Pt film 26. The thickness of the PZT piezoelectric film 17 and the thickness of the AlN piezoelectric film 27 may be different within the range where the relationship H1>H2 exists.

[0039] 18(A) shows a state in which stamp 41 holds multiple AlN piezoelectric films 27 and stamp 42 holds multiple PZT piezoelectric films, and FIG. 18(B) shows the state from the SOI substrate 33 side. FIG. 19(A) shows a state in which AlN piezoelectric films 27 are attached to Pt film 34b of SOI substrate 33, and stamp 42 holding multiple PZT piezoelectric films is attaching one PZT piezoelectric film to Pt film 134a, and FIG. 19(B) shows the state from the SOI substrate 33 side. FIG. 20(A) shows a state in which AlN piezoelectric films 27 are attached to Pt film 34b of another SOI substrate, and stamp 42 holding a PZT piezoelectric film is attaching one PZT piezoelectric film to Pt film 134a, and FIG. 19(B) shows the state from the SOI substrate 33 side.

[0040] In manufacturing the piezoelectric film bonded substrate 200, first, as shown in FIG. 16, the Pt film 13, the sacrificial layer 14, the PZT film 15, and the Pt film 16 are epitaxially grown on a growth substrate (step ST201), and then the portions of the PZT film 15 and the Pt film 16 other than the element regions are removed by etching to form an arbitrary shape (e.g., a rectangle), thereby forming a plurality of PZT piezoelectric films 17 (step ST202).

[0041] Also, as shown in Figure 17, a Pt film 23, a sacrificial layer 24, an AlN film 25, and a Pt film 26 are epitaxially grown on another growth substrate (step ST204), and portions of the AlN film 25 and the Pt film 26 other than the element region are removed by etching to form any shape (e.g., a rectangle), thereby forming multiple AlN piezoelectric films 27 (step ST205).

[0042] Next, a plurality of PZT piezoelectric films 17, each consisting of a PZT film 15 and a Pt film 16, are held by a stamp 42 and peeled off by etching the sacrificial layer (step ST203). Also, a plurality of AlN piezoelectric films 27, each consisting of an AlN film 25 and a Pt film 26, are held by a stamp 41 and peeled off by etching the sacrificial layer (step ST206).

[0043] Next, as shown in FIGS. 18A and 18B, one of the plurality of AlN piezoelectric films 27 held by the stamp 41 is attached onto the Pt film 34b, which is the substrate electrode (step ST207).

[0044] Next, as shown in FIGS. 19(A) and 19(B), one of the plurality of PZT piezoelectric films 17 held by the stamp 42 is attached onto the Pt film 134a, which is the substrate electrode (step ST208).

[0045] 15 are sequentially repeated a number of times corresponding to the number of AlN piezoelectric films 27 held on the stamp 41 and a number of times corresponding to the number of PZT piezoelectric films 17 held on the stamp 42. Note that the number of AlN piezoelectric films 27 held on the stamp 41 and the number of PZT piezoelectric films 17 held on the stamp 42 may be different from each other.

[0046] As shown in FIGS. 18A and 18B, in the second embodiment, contact electrodes and wiring patterns are formed on an SOI substrate 33 using Pt. After an AlN piezoelectric film 27 is attached to a Pt film 34b, a PZT piezoelectric film 17 is attached to a Pt film 134a. When the AlN piezoelectric films 27 held by the stamp 41 are arranged in a 2x2 matrix, they are attached to different SOI substrates 33 in the order of #1, #2, #3, and #4 in the figure. In this example, four SOI substrates 33 are prepared for four piezoelectric films. Next, as shown in FIGS. 19A and 19B, a PZT piezoelectric film 17 is attached to the Pt film 134a. When the PZT piezoelectric films 17 held by the stamp 42 are arranged in a 2x2 matrix, they are attached to different SOI substrates 33 in the order of #1, #2, #3, and #4 in the figure. In this case, since the height H2 of the top of the AlN piezoelectric film 27 is lower than the height H1 of the top of the PZT piezoelectric film 17, as shown in Figure 20(A), the portion 42a of the stamp 42 does not come into contact with the AlN piezoelectric film 27 attached to the Pt film 34b.

[0047] Next, an insulating film 35a and a wiring film 36a are formed on the PZT film 15 and the Pt film 16, and an insulating film 35b and a wiring film 36b are formed on the AlN film 25 and the Pt film 26.

[0048] 2-3 Effects As described above, in the second embodiment, a high-performance piezoelectric film bonded substrate 200 can be produced by forming films on separate growth substrates, peeling them off from the growth substrates, and then stacking and bonding them on a common SOI substrate 33.

[0049] Furthermore, in the second embodiment, by thickening the Pt film 134a, the height H1 of the top of the PZT piezoelectric film 17 is higher than the height H2 of the top of the AlN piezoelectric film 27, so that the lower surface of the stamp 42 and other parts do not come into contact with the AlN piezoelectric film 27 attached to the Pt film 34b.

[0050] In all other respects, the second embodiment is the same as the first embodiment.

[0051] 3. Third Embodiment 3-1 Structure of the piezoelectric film bonded substrate 300 21(A) and (B) are a side view and a top view schematically showing the structure of a piezoelectric film bonded substrate 300 according to embodiment 3. In Fig. 21(A) and (B), components that are the same as or correspond to those shown in Fig. 1 to Fig. 3 are assigned the same reference numerals as those shown in Fig. 1 to Fig. 3.

[0052] Piezoelectric film bonded substrate 300 includes Pt film 334a, which serves as a substrate electrode, provided on glass polyimide laminate substrate 133, PZT piezoelectric film 117, which serves as a first piezoelectric film, attached to Pt film 334a, Pt film 334b, which serves as a substrate electrode provided on glass polyimide laminate substrate 133, and AlN piezoelectric film 127, which serves as a second piezoelectric film, attached to Pt film 334b. PZT piezoelectric film 117 has a structure in which Pt film 13, PZT film 15, and Pt film 16 are laminated, with Pt film 13 attached to Pt film 334a. AlN piezoelectric film 127 has a structure in which Pt film 23, AlN film 25, and Pt film 26 are laminated, with Pt film 13 attached to Pt film 334b. In the third embodiment, the height H1 from the top surface of the glass polyimide laminate substrate 133 on which the Pt films 334a and 334b ​​are formed to the top of the Pt film 16 differs from the height H2 from the top surface of the glass polyimide laminate substrate 133 to the top of the Pt film 26. In the third embodiment, the relationship H1 > H2 holds. The glass polyimide laminate substrate 133 is composed of a glass portion 130 and a polyimide portion 132 overlying the glass portion 130. Apart from the above, the structure of the piezoelectric film bonded substrate 300 is the same as that of the piezoelectric film bonded substrate 100 or 200. Here, the substrate electrodes are formed of platinum (Pt), but this is not necessarily limited to Pt. For example, the substrate electrodes may be formed of various metals such as gold, aluminum, or copper.

[0053] 《3-2》Manufacturing method FIG. 22 is a flowchart illustrating a method for manufacturing a piezoelectric film bonded substrate 200. FIG. 23 is a cross-sectional view schematically illustrating the structure of an epitaxially grown film including a PZT piezoelectric film 117. FIG. 24 is a cross-sectional view schematically illustrating the structure of an epitaxially grown film including an AlN piezoelectric film 127. As shown in FIGS. 23 and 24, in the third embodiment, the thickness of the PZT piezoelectric film 117 (t21=t22+t23+t22) and the thickness of the AlN piezoelectric film 127 (t11=t12+t13+t12) satisfy the relationship t21>t11. This allows the height H1 from the upper surface of the glass polyimide laminated substrate 133 to the top of the Pt film 16 to be greater than the height H2 from the upper surface of the glass polyimide laminated substrate 133 to the top of the Pt film 26.

[0054] 25(A) and 25(B) are a top view and a cross-sectional view schematically showing the structure of a PZT epitaxially grown film in step ST301 of FIG. 22. FIGS. 25(C) and 25(D) are a top view and a cross-sectional view schematically showing the structure of a PZT epitaxially grown film in step ST302 of FIG. 22. FIGS. 26(A) and 26(B) are a top view and a cross-sectional view schematically showing the structure of an AlN epitaxially grown film in step ST304 of FIG. 22. FIGS. 26(C) and 26(D) are a top view and a cross-sectional view schematically showing the structure of an AlN epitaxially grown film in step ST305 of FIG. 22. FIGS. 27(A) and 27(B) are cross-sectional views schematically showing the holding process of multiple PZT piezoelectric films 117 in step ST303 of FIG. 22. 28(A) and 28(B) are cross-sectional views schematically showing the process of holding a plurality of AlN piezoelectric films 127 in step ST306 of FIG. 22. FIG. 29(A) is a cross-sectional view schematically showing the process of bonding the AlN piezoelectric films 127 in step ST307 of FIG. 22, and FIG. 29(B) is a top view showing the position where the AlN piezoelectric films 127 are bonded. FIG. 30(A) is a cross-sectional view schematically showing the process of bonding the PZT piezoelectric films 117 in step ST308 of FIG. 22, and FIG. 30(B) is a top view showing the state where the PZT piezoelectric films 117 have been bonded. FIG. 31(A) is a cross-sectional view showing the next manufacturing process of a piezoelectric film bonded substrate, and FIG. 31(B) is a top view showing the state where the PZT piezoelectric films 117 have been bonded.

[0055] In manufacturing the piezoelectric film bonded substrate 300, first, as shown in FIG. 25(A), the sacrificial layer 14, the Pt film 13, the PZT film 15, and the Pt film 16 are epitaxially grown on a growth substrate (step ST301), and then the portions of the Pt film 13, the PZT film 15, and the Pt film 16 other than the element regions are removed by etching to form an arbitrary shape (e.g., a rectangle), thereby forming a plurality of PZT piezoelectric films 117 (step ST302).

[0056] Also, as shown in Figure 26(A), a sacrificial layer 24, a Pt film 23, an AlN film 25, and a Pt film 26 are epitaxially grown on another growth substrate (step ST304), and portions of the AlN film 25 and the Pt film 26 other than the element region are removed by etching to form any shape (e.g., a rectangle), thereby forming multiple AlN piezoelectric films 127 (step ST205).

[0057] Next, a plurality of PZT piezoelectric films 117, each consisting of a Pt film 13, a PZT film 15, and a Pt film 16, are held by a stamp 42 and peeled off by etching the sacrificial layer (step ST303). Also, a plurality of AlN piezoelectric films 127, each consisting of a Pt film 23, an AlN film 25, and a Pt film 26, are held by a stamp 41 and peeled off by etching the sacrificial layer (step ST306).

[0058] Next, as shown in FIGS. 29(A) and 29(B), one of the plurality of AlN piezoelectric films 127 held by the stamp 41 is attached onto the Pt film 334b, which is the substrate electrode (step ST307).

[0059] Next, as shown in FIGS. 30(A) and 30(B), one of the plurality of PZT piezoelectric films 117 held by the stamp 42 is attached onto the Pt film 334a, which is the substrate electrode (step ST308).

[0060] 22 are sequentially repeated a number of times corresponding to the number of AlN piezoelectric films 127 held on the stamp 41 and a number of times corresponding to the number of PZT piezoelectric films 117 held on the stamp 42. Note that the number of AlN piezoelectric films 127 held on the stamp 41 and the number of PZT piezoelectric films 117 held on the stamp 42 may be different from each other.

[0061] As shown in FIGS. 29A and 29B, in the third embodiment, contact electrodes and wiring patterns are formed on a glass polyimide laminate substrate 133 using Pt. After the AlN piezoelectric film 127 is attached to the Pt film 334b, the PZT piezoelectric film 117 is attached to the Pt film 334a. When the AlN piezoelectric films 127 held by the stamp 41 are arranged in a 2x2 matrix, they are attached to different glass polyimide laminate substrates 133 in the order of #1, #2, #3, and #4 in the figure. In this example, four glass polyimide laminate substrates 133 are prepared for four piezoelectric films. Next, as shown in FIGS. 30A and 30B, the PZT piezoelectric film 117 is attached to the Pt film 334a. When the PZT piezoelectric films 117 held by the stamp 42 are arranged in a 2x2 matrix, they are attached to different glass polyimide laminate substrates 133 in the order of #1, #2, #3, and #4 in the figure. In this case, since the height H2 of the top of the AlN piezoelectric film 127 is lower than the height H1 of the top of the PZT piezoelectric film 117, as shown in Figure 31(A), the portion 42a of the underside of the stamp 42 does not come into contact with the AlN piezoelectric film 127 attached to the Pt film 334b.

[0062] Next, an insulating film 35a and a wiring film 36a are formed on the PZT film 15 and the Pt film 16, and an insulating film 35b and a wiring film 36b are formed on the AlN film 25 and the Pt film 26.

[0063] 3-3 Effect As described above, in the third embodiment, a high-performance piezoelectric film bonded substrate 200 can be produced by epitaxially growing the piezoelectric film on a separate growth substrate, peeling it off from the growth substrate, and then laminating and bonding it on a common glass-polyimide laminated substrate 133.

[0064] Furthermore, in embodiment 3, the height H1 of the top of the PZT piezoelectric film 117 is greater than the height H2 of the top of the AlN piezoelectric film 127, so that the lower surface of the stamp 42 and other portions do not come into contact with the AlN piezoelectric film 127 attached to the Pt film 334b.

[0065] Furthermore, according to the manufacturing method of the third embodiment, the AlN piezoelectric film and the PZT piezoelectric film, each with an electrode, are attached to the substrate electrode, so that annealing treatment for stabilizing the characteristics is not required, and multiple piezoelectric films with different crystal structures can be provided on a non-heat-resistant substrate such as a glass polyimide laminate substrate 133.

[0066] In all other respects, the third embodiment is the same as the first or second embodiment. [Explanation of symbols]

[0067] 13 Pt film (bottom electrode film), 15 PZT film (piezoelectric film), 16 Pt film (top electrode film), 17, 117 PZT piezoelectric film (piezoelectric film), 23 Pt film (bottom electrode film), 25 AlN film (piezoelectric film), 26 Pt film (top electrode film), 27, 127 AlN piezoelectric film (piezoelectric film), 33 SOI substrate (substrate), 34a, 134a Pt film (substrate electrode), 34b Pt film (substrate electrode), 41, 42 Stamp (holding member), 100, 100a, 200, 300 Piezoelectric film bonded substrate, 133 Glass polyimide laminated substrate, 334a Pt film (substrate electrode), 334b ​​Pt film (substrate electrode), t1, t21 PZT piezoelectric film thickness, t4, t25 Film thickness of AlN piezoelectric film, t11 Film thickness of PZT piezoelectric film or AlN piezoelectric film.

Claims

1. A method for manufacturing a piezoelectric film bonded substrate having a device substrate and a first piezoelectric film and a second piezoelectric film having different film thicknesses, peeling the first piezoelectric film formed on the first substrate and the second piezoelectric film formed on the second substrate from the first substrate and the second substrate, respectively; When the piezoelectric film having a thinner film thickness of the first piezoelectric film and the second piezoelectric film is designated as a first film thickness, and the piezoelectric film having a thicker film thickness is designated as a second film thickness, the film having the first film thickness is attached to a first electrode formed on the device substrate, After the film having the first thickness is attached, the film having the second thickness is attached onto the second electrode formed on the device substrate.

10. A method for manufacturing a piezoelectric film-bonded substrate, comprising:

2. A method for manufacturing a piezoelectric film bonded substrate having a device substrate having a first electrode and a second electrode with different film thicknesses, a first piezoelectric film, and a second piezoelectric film, the method comprising: peeling the first piezoelectric film formed on the first substrate and the second piezoelectric film formed on the second substrate from the first substrate and the second substrate, respectively; When the electrode having a larger film thickness of the first electrode and the second electrode is designated as the electrode having a first film thickness and the electrode having a smaller film thickness is designated as the electrode having a second film thickness, the second piezoelectric film is attached onto the electrode having the second film thickness formed on the device substrate, After the film having the second thickness is attached, the first piezoelectric film is attached onto the first electrode.

10. A method for manufacturing a piezoelectric film-bonded substrate, comprising:

3. the first piezoelectric film has a first piezoelectric film and a first upper electrode film formed on the first piezoelectric film, The second piezoelectric film has a second piezoelectric film different from the first piezoelectric film and a second upper electrode film formed on the second piezoelectric film.

3. The method for manufacturing a piezoelectric film-bonded substrate according to claim 1 or 2.

4. the first piezoelectric film further includes a first lower electrode film formed on a surface of the first piezoelectric film opposite to the first upper electrode film, The second piezoelectric film further includes a second lower electrode film formed on the surface of the second piezoelectric film opposite to the second upper electrode film.

4. The method for manufacturing a piezoelectric film-bonded substrate according to claim 3.

5. The first piezoelectric film is a single crystal, and the second piezoelectric film is a single crystal.

5. The method for manufacturing a piezoelectric film-bonded substrate according to claim 3 or 4.

6. an area of ​​a surface of the first electrode is larger than an area of ​​an attachment surface of the first piezoelectric film attached to the surface of the first electrode; The surface area of ​​the second electrode is larger than the surface area of ​​the second piezoelectric film attached to the surface of the second electrode. The method for manufacturing a piezoelectric film-bonded substrate according to any one of claims 1 to 5.

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