Ferroelectric film-formed substrate manufacturing method and ferroelectric film-formed substrate

Abstract

This method for manufacturing a piezoelectric film forming substrate (100) comprises: a step for forming a piezoelectric film (3) on a lower electrode (2) while a mask (5) is attached to the lower electrode; a step for forming an upper electrode (4) on the piezoelectric film while the mask is attached to the lower electrode; a step for removing the mask from the lower electrode and forming a lower electrode exposed part (2a); and a step for performing a polarizing process on the piezoelectric film by applying a voltage between the lower electrode exposed part and the upper electrode.

Description

[Technical Field]

[0001] The present invention relates to a method for manufacturing a ferroelectric film-formed substrate and a ferroelectric film-formed substrate, and more particularly to a method for manufacturing a ferroelectric film-formed substrate and a ferroelectric film-formed substrate in which a polarization treatment of a ferroelectric film is performed. [Background technology]

[0002] A method for manufacturing a thin film micromechanical resonator gyro in which a polarization process is performed on a piezoelectric thin film has been known in the past, and is disclosed in, for example, Japanese Patent Application Laid-Open No. 2003-302222.

[0003] The aforementioned Japanese Patent Application Laid-Open Publication No. 2003-302222 discloses a manufacturing method for a thin-film micromechanical resonator gyro in which a piezoelectric thin film is polarized. In this manufacturing method, a lower electrode, a piezoelectric thin film, and an upper electrode are formed in this order on a silicon wafer, and the piezoelectric thin film and upper electrode are patterned by photolithography. As a result, multiple thin-film micromechanical resonator gyros are formed on the silicon wafer. The silicon wafer on which the multiple thin-film micromechanical resonator gyros are formed is then divided into multiple individual thin-film micromechanical resonator gyros. In this manufacturing method, when the piezoelectric thin film and upper electrode are patterned by photolithography, an exposed portion of the lower electrode for polarization is also formed by photolithography. Then, a conductive sheet is placed to cover the upper electrode of each thin-film micromechanical resonator gyro, and a voltage is applied between the exposed portion of the lower electrode and the conductive sheet covering the upper electrode, thereby polarizing the piezoelectric thin films of each thin-film micromechanical resonator gyro all at once. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2003-302222 Summary of the Invention [Problem to be solved by the invention]

[0005] In the manufacturing method of a thin film mechanical resonator gyro described in the above-mentioned JP 2003-302222 A, while it is possible to polarize the piezoelectric thin film all at once, the exposed portion of the lower electrode is formed by photolithography, which requires complex processes such as forming a resist film and etching. Therefore, when polarizing the piezoelectric thin film (ferroelectric film) all at once, there is a problem in that it is difficult to easily form the exposed portion of the lower electrode (exposed portion of the lower electrode).

[0006] The present invention has been made to solve the above-mentioned problems, and one object of the present invention is to provide a method for manufacturing a ferroelectric film-formed substrate and a ferroelectric film-formed substrate that enable easy formation of a lower electrode exposed portion even when the ferroelectric film is polarized collectively. [Means for solving the problem]

[0007] In order to achieve the above object, a method for manufacturing a ferroelectric film-formed substrate according to a first aspect of the present invention is a method for manufacturing a ferroelectric film-formed substrate that is divided into a plurality of pieces each of which becomes a device, the method comprising the steps of: preparing a substrate; , so as to connect to the outer edge of the board A step of forming a lower electrode; At least a part of the outer periphery of the step of attaching a mask on top, the step of forming a ferroelectric film on the lower electrode with the mask attached on the lower electrode, the step of forming an upper electrode on the ferroelectric film with the mask attached on the lower electrode, the step of removing the mask from over the lower electrode to expose a portion of the lower electrode on which the ferroelectric film and the upper electrode are not formed, thereby forming an exposed portion of the lower electrode, and the step of applying a voltage between the exposed portion of the lower electrode and the upper electrode to polarize the ferroelectric film.

[0008] In the method for manufacturing a ferroelectric film-formed substrate according to the first aspect of the present invention, as described above, At least a part of the outer periphery ofThe method includes the steps of attaching a mask on the lower electrode, forming a ferroelectric film on the lower electrode with the mask attached to the lower electrode, forming an upper electrode on the ferroelectric film with the mask attached to the lower electrode, removing the mask from the lower electrode to expose a portion of the lower electrode where the ferroelectric film and the upper electrode are not formed, thereby forming an exposed lower electrode portion, and applying a voltage between the exposed lower electrode portion and the upper electrode to polarize the ferroelectric film. This allows the ferroelectric film to be polarized all at once before dividing the ferroelectric film-formed substrate into multiple pieces. Furthermore, since the exposed lower electrode portion is formed without using a mask to form the ferroelectric film and the upper electrode, the exposed lower electrode portion can be easily formed without requiring complex processes compared to forming the exposed lower electrode portion by photolithography, which involves forming a resist film and etching. As a result, the exposed lower electrode portion can be easily formed even when the ferroelectric film is polarized all at once. Furthermore, since the ferroelectric film can be polarized all at once before the ferroelectric film-formed substrate is divided into a plurality of individual pieces, the time required for the polarization treatment of the ferroelectric film can be shortened compared to when the ferroelectric film is polarized for each individual piece after the ferroelectric film-formed substrate is divided into a plurality of individual pieces.

[0009] In the method for manufacturing a ferroelectric film-formed substrate according to the first aspect, the step of attaching a mask to the lower electrode preferably includes attaching a mask to at least a portion of the outer periphery of the lower electrode included in the exclusion region not used for the device, and the step of forming the lower electrode exposed portion preferably includes forming the lower electrode exposed portion on at least a portion of the outer periphery of the lower electrode included in the exclusion region. This configuration allows the lower electrode exposed portion to be formed by utilizing the exclusion region not used for the device, thereby preventing a reduction in the area usable for the device due to the formation of the lower electrode exposed portion. As a result, a decrease in device yield can be avoided. Furthermore, since the outer periphery of the lower electrode is an area where a mask is more easily attached than the inner periphery, the mask can be attached easily.

[0010] In this case, preferably, the step of attaching a mask onto the lower electrode includes the step of attaching a mask having an arc-shaped configuration with a constant curvature onto at least a part of the outer periphery of the lower electrode, and the step of forming the lower electrode exposed portion includes the step of forming the lower electrode exposed portion having an arc-shaped configuration with a constant curvature on at least a part of the outer periphery of the lower electrode. With this configuration, since the lower electrode exposed portion has an arc-shaped configuration with a constant curvature, it is possible to easily form the lower electrode exposed portion so that it is included in the exclusion region.

[0011] In the method for manufacturing a ferroelectric film-formed substrate according to the first aspect, the step of poling the ferroelectric film preferably includes a step of poling the ferroelectric film by applying a voltage between the exposed portion of the lower electrode and the upper electrode before processing the upper electrode for device use. This configuration allows the polarization treatment to be performed before the upper electrode is electrically separated by the processing for device use. Therefore, unlike the case where the upper electrodes are electrically connected by a conductive member after the upper electrodes are electrically separated by the processing for device use, no conductive member is required. As a result, the polarization treatment can be easily performed.

[0012] In the method for manufacturing a ferroelectric film-formed substrate according to the first aspect, the ferroelectric film is preferably a piezoelectric film. With this configuration, the exposed portion of the lower electrode can be easily formed even when the piezoelectric film is polarized all at once.

[0013] In order to achieve the above object, a ferroelectric film-formed substrate according to a second aspect of the present invention is a ferroelectric film-formed substrate that is divided into a plurality of pieces each of which becomes a device, and includes a substrate, a lower electrode formed on the substrate, a ferroelectric film formed on the lower electrode, and an upper electrode formed on the ferroelectric film and not subjected to processing for device use, wherein the lower electrode is formed on the outer periphery of the substrate end The ferroelectric film and the exposed portion of the lower electrode on which the upper electrode is not formed are connected to at least a part of the upper electrode, and the ferroelectric film is polarized.

[0014] In a ferroelectric film-formed substrate according to a second aspect of the present invention, as described above, the lower electrode is connected to at least a portion of the outer peripheral edge of the substrate and includes a lower electrode exposed portion where the ferroelectric film and upper electrode are not formed, the upper electrode is not processed for device use, and the ferroelectric film is polarized. This makes it possible to obtain a ferroelectric film-formed substrate in which the ferroelectric film is polarized all at once before dividing the ferroelectric film-formed substrate into multiple individual pieces. Furthermore, since the lower electrode exposed portion is formed by not forming the ferroelectric film and upper electrode, the lower electrode exposed portion can be easily formed without requiring complex processes compared to forming the lower electrode exposed portion by photolithography, which involves forming a resist film and etching, for example. As a result, a ferroelectric film-formed substrate in which the lower electrode exposed portion can be easily formed can be provided, even when the ferroelectric film is polarized all at once. Furthermore, since the polarization process can be performed before the upper electrode is electrically separated into individual pieces by the device processing process, the polarization process can be performed more easily than when the upper electrodes of each device are electrically connected with a conductive member and then polarized after the upper electrodes have been electrically separated into individual pieces by the device processing process. In the aforementioned ferroelectric film-formed substrate according to the second aspect, the substrate is preferably not divided into a plurality of individual pieces. In the aforementioned ferroelectric film-formed substrate according to the second aspect, the upper electrode is preferably formed on substantially the entire surface of the ferroelectric film. In the ferroelectric film-formed substrate according to the second aspect, the ferroelectric film is preferably formed in an exclusion region of the substrate that is not used as a device. [Effects of the Invention]

[0015] According to the present invention, as described above, even when the ferroelectric film is polarized collectively, the exposed portion of the lower electrode can be easily formed. [Brief explanation of the drawings]

[0016] [Figure 1] FIG. 1 is a plan view showing a piezoelectric film-formed substrate according to an embodiment. [Figure 2] 1 is a cross-sectional view showing a piezoelectric film-formed substrate according to an embodiment. [Figure 3] 1A-1C are plan views illustrating a substrate during manufacturing steps according to one embodiment. [Figure 4] 1A-1D are cross-sectional views illustrating a substrate during manufacturing steps according to one embodiment. [Figure 5] FIG. 10 is a plan view showing a state in which a lower electrode is formed in a manufacturing process according to one embodiment. [Figure 6] 10A and 10B are cross-sectional views illustrating a state in which a lower electrode is formed in a manufacturing process according to one embodiment. [Figure 7] FIG. 10 is a plan view showing a state in which a mask is attached in a manufacturing process according to an embodiment. [Figure 8] 10A and 10B are cross-sectional views showing a state in which a mask is attached in a manufacturing process according to one embodiment. [Figure 9] FIG. 2 is a plan view showing a state in which a piezoelectric film is formed in a manufacturing process according to one embodiment. [Figure 10] 5A to 5C are cross-sectional views showing a state in which a piezoelectric film is formed in a manufacturing process according to one embodiment. [Figure 11] FIG. 10 is a plan view showing a state in which an upper electrode is formed in a manufacturing process according to one embodiment. [Figure 12] 10A and 10B are cross-sectional views illustrating a state in which an upper electrode is formed in a manufacturing process according to one embodiment. [Figure 13] FIG. 1 is a plan view illustrating a state in which a mask is removed during a manufacturing process according to an embodiment. [Figure 14] 1A and 1B are cross-sectional views illustrating a state in which a mask is removed during a manufacturing process according to an embodiment. [Figure 15] 5A to 5C are schematic diagrams illustrating a polarization treatment state in a manufacturing process according to one embodiment. [Figure 16] 1 is a plan view for explaining division of a piezoelectric film-formed substrate into a plurality of pieces according to an embodiment. FIG. [Figure 17] FIG. 10 is a plan view showing a piezoelectric film-formed substrate according to a first modified example of an embodiment. [Figure 18] FIG. 10 is a plan view showing a piezoelectric film-formed substrate according to a second modified example of the embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0017] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0018] (Configuration of piezoelectric film deposition substrate) The configuration of a piezoelectric film-forming substrate 100 according to one embodiment of the present invention will be described with reference to Figures 1 and 2. The piezoelectric film-forming substrate 100 is an example of the "ferroelectric film-forming substrate" in the claims.

[0019] The piezoelectric film-formed substrate 100 is a piezoelectric film-formed substrate that is divided into a plurality of pieces P (see FIG. 16), each of which becomes a device. Each of the plurality of pieces P becomes a device. The device is, for example, a MEMS (Micro Electro Mechanical Systems) device. The MEMS device is, for example, a MEMS gyro element. The device and the MEMS device are not particularly limited.

[0020] 1 and 2, the piezoelectric film-forming substrate 100 includes a substrate 1, a lower electrode 2, a piezoelectric film 3, and an upper electrode 4. The piezoelectric film 3 is an example of the "ferroelectric film" in the claims.

[0021] The substrate 1 is a silicon wafer substrate. The substrate 1 is circular. The lower electrode 2 is formed on the substrate 1. The lower electrode 2 is formed on substantially the entire surface of the substrate 1. The lower electrode 2 is formed of a metal film such as a Pt / Ti film. In this embodiment, the lower electrode 2 includes a lower electrode exposed portion 2a. The lower electrode exposed portion 2a is formed by exposing a portion of the lower electrode 2 on which the piezoelectric film 3 and the upper electrode 4 are not formed. The lower electrode exposed portion 2a is connected to at least a portion (the entire portion in this embodiment) of the outer periphery of the substrate 1. The lower electrode exposed portion 2a is formed in an arc-shaped shape with a certain curvature (annular in this embodiment) on at least a portion (the entire portion in this embodiment) of the outer periphery of the lower electrode 2 included in an exclusion region A (see FIG. 3 ) that is not used as a device. The exclusion region (chip exclusion region) A is a region where performance is not guaranteed, and is an annular region having a width of approximately several mm extending inward from the outer periphery of the substrate 1.

[0022] The piezoelectric film 3 is formed on the lower electrode 2. The piezoelectric film 3 is formed on substantially the entire surface of the lower electrode 2 except for the exposed portion 2a of the lower electrode. The piezoelectric film 3 is formed of a ferroelectric film such as a lead zirconate titanate (PZT) film. In this embodiment, the piezoelectric film 3 is polarized. The upper electrode 4 is formed on the piezoelectric film 3. The upper electrode 4 is formed on substantially the entire surface of the piezoelectric film 3. The upper electrode 4 is formed of a metal film such as an Au / Ti film. In this embodiment, the upper electrode 4 has not been processed for use in a device. The lower electrode 2 and the piezoelectric film 3 have not been processed for use in a device. The processing for processing for a device is a process for processing into a shape for a device. For example, a process for processing into a shape for a device is performed by photolithography. In the case of photolithography, a process for processing into a shape for a device is performed by removing unnecessary portions and leaving necessary portions by wet etching using an etching solution or dry etching using an etching gas.

[0023] (Method of manufacturing a piezoelectric film-formed substrate) 3 to 15, a method for manufacturing a piezoelectric film-formed substrate 100 will be described. The method for manufacturing the piezoelectric film-formed substrate 100 is a method for manufacturing a piezoelectric film-formed substrate that is divided into a plurality of pieces P (see FIG. 16), each of which will become a device. In this embodiment, the method for manufacturing the piezoelectric film-formed substrate 100 includes the steps of preparing a substrate 1, forming a lower electrode 2 on the substrate 1, attaching a mask 5 to the lower electrode 2, forming a piezoelectric film 3 on the lower electrode 2 with the mask 5 attached to the lower electrode 2, forming an upper electrode 4 on the piezoelectric film 3 with the mask 5 attached to the lower electrode 2, removing the mask 5 from the lower electrode 2 to expose a portion of the lower electrode 2 where the piezoelectric film 3 and upper electrode 4 are not formed, thereby forming an exposed lower electrode portion 2a, and applying a voltage between the exposed lower electrode portion 2a and the upper electrode 4 to polarize the piezoelectric film 3.

[0024] As shown in FIGS. 3 and 4, in the step of preparing the substrate 1, a circular silicon wafer substrate is prepared. As shown in FIGS. 5 and 6, in the step of forming the lower electrode 2 on the substrate 1, a metal film is deposited over substantially the entire surface of the substrate 1, for example, by sputtering. As a result, the lower electrode 2 is formed over substantially the entire surface of the substrate 1. As shown in FIGS. 7 and 8, in the step of attaching a mask 5 to the lower electrode 2, a mask 5 having an arc-like shape with a certain curvature (annular in this embodiment) is attached to at least a portion (the entire in this embodiment) of the outer periphery of the lower electrode 2 included in the exclusion region A not used as a device. As a result, at least a portion (the entire in this embodiment) of the outer periphery of the lower electrode 2 is covered with the mask 5. The mask 5 is a stencil mask made of a material such as metal or SiC.

[0025] 9 and 10, in the step of forming the piezoelectric film 3 on the lower electrode 2, a ferroelectric film is deposited by sputtering, for example, with a mask 5 attached to the lower electrode 2, over substantially the entire surface of the lower electrode 2 except for the portion covered by the mask 5. As a result, the piezoelectric film 3 is formed over substantially the entire surface of the lower electrode 2 except for the portion covered by the mask 5. As shown in FIGS. 11 and 12, in the step of forming the upper electrode 4 on the piezoelectric film 3, a metal film is deposited by sputtering, for example, with a mask 5 attached to the lower electrode 2. As a result, the upper electrode 4 is formed over substantially the entire surface of the piezoelectric film 3. Note that the upper electrode 4 is not formed on the lower electrode 2 covered by the mask 5.

[0026] As shown in FIGS. 13 and 14 , in the step of forming the lower electrode exposed portion 2a, the mask 5 is removed from the lower electrode 2 to expose a portion of the lower electrode 2 on which the piezoelectric film 3 and the upper electrode 4 are not formed, thereby forming the lower electrode exposed portion 2a. At this time, the lower electrode exposed portion 2a has an arc-like shape (annular in this embodiment) with a certain curvature on at least a portion (the entire outer periphery in this embodiment) of the outer periphery of the lower electrode 2 included in the exclusion region A (see FIG. 3 ). The mask 5 is removed from the lower electrode 2 immediately after the step of forming the upper electrode 4 on the piezoelectric film 3. The mask 5 may be disposable or may be reused. If reused, it may be cleaned and reused. Cleaning and reusing the mask 5 can prevent any substances attached to the mask 5 during the previous manufacturing of the piezoelectric film-formed substrate 100 from adversely affecting the manufacturing of the current piezoelectric film-formed substrate 100.

[0027] 15, in the step of polarizing the piezoelectric film 3, a voltage is applied between the lower electrode exposed portion 2a and the upper electrode 4 via the probe 6 while the probe 6 is in contact with the lower electrode exposed portion 2a and the upper electrode 4, respectively, thereby polarizing the piezoelectric film 3. The polarization aligns the direction of spontaneous polarization of the piezoelectric film 3 in one direction. Note that during the polarization process, the probe 6 may be in contact with the lower electrode exposed portion 2a and the upper electrode 4 at one location each, and a voltage may be applied, or the probe 6 may be in contact with the lower electrode exposed portion 2a and the upper electrode 4 at multiple locations each, and a voltage may be applied.

[0028] In this embodiment, the process of poling the piezoelectric film 3 is performed before the process of processing the upper electrode 4 for a device (see FIG. 16). That is, the process of poling the piezoelectric film 3 is performed before processing the upper electrode 4 into a shape for a device, for example by photolithography. The process of poling the piezoelectric film 3 is performed in a state where the entire upper electrode 4 is electrically connected, before the upper electrode 4 is electrically separated into individual pieces P by processing the upper electrode 4 into a shape for a device. In this way, the piezoelectric film-formed substrate 100 is manufactured.

[0029] 16 , when the piezoelectric film-formed substrate 100 is divided into device pieces P, the piezoelectric film-formed substrate 100 is cut into the device pieces P using, for example, a blade. The process of processing the upper electrode 4, the piezoelectric film 3, the lower electrode 2, etc. for devices may be performed either before or after the piezoelectric film-formed substrate 100 is divided into the multiple pieces P. That is, after the piezoelectric film-formed substrate 100 is divided into the multiple pieces P, the process of processing the upper electrode 4, the piezoelectric film 3, the lower electrode 2, etc. for devices may be performed on each of the divided pieces P. Alternatively, the piezoelectric film-formed substrate 100 may be divided into the multiple pieces P after the process of processing the upper electrode 4, the piezoelectric film 3, the lower electrode 2, etc. for devices is performed. Because the polarization process is performed before the process of processing the upper electrode 4, the piezoelectric film 3, the lower electrode 2, etc. for devices, either process can be used.

[0030] (Effects of this embodiment) In this embodiment, the following effects can be obtained.

[0031] In this embodiment, as described above, the method for manufacturing a piezoelectric film-formed substrate 100 is a method for manufacturing a piezoelectric film-formed substrate 100 that is divided into a plurality of individual pieces P, each of which becomes a device, and includes the steps of preparing a substrate 1, forming a lower electrode 2 on the substrate 1, attaching a mask 5 to the lower electrode 2, forming a piezoelectric film 3 on the lower electrode 2 with the mask 5 attached to the lower electrode 2, forming an upper electrode 4 on the piezoelectric film 3 with the mask 5 attached to the lower electrode 2, removing the mask 5 from the lower electrode 2 to expose the portion of the lower electrode 2 on which the piezoelectric film 3 and upper electrode 4 are not formed, thereby forming an exposed portion 2a of the lower electrode, and applying a voltage between the exposed portion 2a of the lower electrode and the upper electrode 4 to polarize the piezoelectric film 3.

[0032] With the above configuration, the piezoelectric film 3 can be polarized all at once before the piezoelectric film-formed substrate 100 is divided into the plurality of pieces P. Furthermore, since the lower electrode exposed portion 2a is formed by not forming the piezoelectric film 3 and the upper electrode 4 using the mask 5, the lower electrode exposed portion 2a can be formed easily without requiring complex processes, compared to forming the lower electrode exposed portion 2a by photolithography, which involves forming a resist film and etching. As a result, the lower electrode exposed portion 2a can be easily formed even when the piezoelectric film 3 is polarized all at once. Furthermore, since the piezoelectric film 3 can be polarized all at once before the piezoelectric film-formed substrate 100 is divided into the plurality of pieces P, the time required for the polarization of the piezoelectric film 3 can be shortened compared to when the piezoelectric film 3 is polarized for each piece P after the piezoelectric film-formed substrate 100 is divided into the plurality of pieces P.

[0033] In this embodiment, as described above, the step of attaching the mask 5 to the lower electrode 2 includes attaching the mask 5 to at least a portion of the outer periphery of the lower electrode 2 included in the exclusion region A that is not used as a device, and the step of forming the lower electrode exposed portion 2a includes forming the lower electrode exposed portion 2a on at least a portion of the outer periphery of the lower electrode 2 included in the exclusion region A. This allows the exclusion region A that is not used as a device to be utilized to form the lower electrode exposed portion 2a, thereby preventing a reduction in the area that can be used as a device due to the formation of the lower electrode exposed portion 2a. As a result, a decrease in device yield can be avoided. Furthermore, since the outer periphery of the lower electrode 2 is an area where it is easier to attach the mask 5 than the inner periphery, the mask 5 can be easily attached.

[0034] In this embodiment, as described above, the step of attaching the mask 5 onto the lower electrode 2 includes the step of attaching the mask 5 having an arc-like shape with a constant curvature onto at least a part of the outer periphery of the lower electrode 2, and the step of forming the lower electrode exposed portion 2a includes the step of forming the lower electrode exposed portion 2a having an arc-like shape with a constant curvature onto at least a part of the outer periphery of the lower electrode 2. As a result, since the lower electrode exposed portion 2a has an arc-like shape with a constant curvature, the lower electrode exposed portion 2a can be easily formed so as to be included in the exclusion region A.

[0035] In this embodiment, as described above, the process of poling the piezoelectric film 3 includes a process of poling the piezoelectric film 3 by applying a voltage between the exposed portion 2a of the lower electrode and the upper electrode 4 before processing the upper electrode 4 for device use. This allows the polarization process to be performed before the upper electrode 4 is electrically separated by processing for device use, so no conductive member is required, unlike when the separated upper electrodes 4 are electrically connected by a conductive member and then polarized after the upper electrodes 4 are electrically separated by processing for device use. As a result, the polarization process can be performed easily.

[0036] In this embodiment, as described above, the ferroelectric film is the piezoelectric film 3. This makes it possible to easily form the bottom electrode exposed portion 2a even when the piezoelectric film 3 is polarized all at once.

[0037] In this embodiment, as described above, the lower electrode 2 is connected to at least a portion of the outer periphery of the substrate 1 and includes a lower electrode exposed portion 2a where the piezoelectric film 3 and upper electrode 4 are not formed, the upper electrode 4 is not processed for device use, and the piezoelectric film 3 is polarized. This allows for a piezoelectric film-formed substrate 100 in which the piezoelectric film 3 is polarized all at once before the piezoelectric film-formed substrate 100 is divided into multiple individual pieces P. Furthermore, because the lower electrode exposed portion 2a is formed without forming the piezoelectric film 3 and upper electrode 4, the lower electrode exposed portion 2a can be formed more easily without requiring complex processes compared to forming the lower electrode exposed portion 2a by photolithography, which involves forming a resist film and etching. As a result, a piezoelectric film-formed substrate 100 in which the lower electrode exposed portion 2a can be easily formed can be provided, even when the piezoelectric film 3 is polarized all at once. Furthermore, since the polarization treatment can be performed before the upper electrodes 4 are electrically separated by the processing for device use, the polarization treatment can be performed more easily than when the separated upper electrodes 4 are electrically connected to each other with a conductive member and then polarized after the upper electrodes 4 are electrically separated by the processing for device use.

[0038] (Variation) The embodiments disclosed herein should be considered to be illustrative and not restrictive in all respects. The scope of the present invention is defined by the claims, not by the description of the above embodiments, and includes all modifications (variations) within the meaning and scope of the claims.

[0039] For example, in the above embodiment, a piezoelectric film is used as the ferroelectric film, but the present invention is not limited to this. For example, a pyroelectric film may be used as the ferroelectric film.

[0040] In the above embodiment, the lower electrode exposed portion is formed on the outer periphery of the lower electrode included in the exclusion region, but the present invention is not limited to this. For example, the lower electrode exposed portion may be formed on the inner side of the outer periphery of the lower electrode.

[0041] Although the above embodiment illustrates an example in which a circular bottom electrode exposed portion is formed, the present invention is not limited thereto. For example, in a first modification shown in FIG. 17, one arc-shaped (arc-shaped with a constant curvature) bottom electrode exposed portion 2a is formed on the outer periphery of the bottom electrode 2. In this case, in the step of attaching a mask 5 to the bottom electrode 2, the arc-shaped (arc-shaped with a constant curvature) mask 5 is attached on the outer periphery of the bottom electrode 2. In addition, in the step of forming the bottom electrode exposed portion 2a, the arc-shaped (arc-shaped with a constant curvature) bottom electrode exposed portion 2a is formed on the outer periphery of the bottom electrode 2. This allows the bottom electrode exposed portion 2a to be formed in a relatively narrow area, thereby further preventing a reduction in the area usable as a device due to the formation of the bottom electrode exposed portion 2a. As a result, a decrease in device yield can be further prevented. Furthermore, as in a second modification shown in FIG. 18, multiple (four in FIG. 18) arc-shaped (arc-shaped with a constant curvature) bottom electrode exposed portions 2a may be formed on the outer periphery of the bottom electrode 2.

[0042] Furthermore, the lower electrode exposed portions in the above embodiment, the above first modified example, and the above second modified example are merely examples, and the position, shape, number, etc. of the lower electrode exposed portions are not particularly limited.

[0043] In the above embodiment, the piezoelectric film (ferroelectric film) is polarized before the upper electrode is processed for device use, but the present invention is not limited to this. For example, the ferroelectric film may be polarized after the upper electrode is processed for device use. In this case, the ferroelectric film may be polarized while the upper electrodes, which are electrically separated by the process for device use, are electrically connected by a conductive member. [Explanation of symbols]

[0044] 1 board 2 Lower electrode 3. Piezoelectric film (ferroelectric film) 4 Upper electrode 5. Mask 100 Piezoelectric film deposition substrate (ferroelectric film deposition substrate) A. Exclusion Area P piece

Claims

1. A method for manufacturing a ferroelectric film-formed substrate that is divided into a plurality of pieces each of which becomes a device, comprising the steps of: providing a substrate; forming a lower electrode on the substrate so as to be connected to an outer peripheral edge of the substrate; applying a mask over at least a portion of the outer periphery of the bottom electrode; forming a ferroelectric film on the lower electrode with the mask attached on the lower electrode; forming an upper electrode on the ferroelectric film while the mask is attached on the lower electrode; removing the mask from above the lower electrode to expose a portion of the lower electrode on which the ferroelectric film and the upper electrode are not formed, thereby forming a lower electrode exposed portion; and applying a voltage between the exposed portion of the lower electrode and the upper electrode to polarize the ferroelectric film.

2. the step of attaching the mask to the lower electrode includes attaching the mask to at least a part of an outer periphery of the lower electrode included in an exclusion region that is not used for the device; 2. The method for manufacturing a ferroelectric film-formed substrate according to claim 1, wherein the step of forming the lower electrode exposed portion includes the step of forming the lower electrode exposed portion in at least a part of the outer periphery of the lower electrode included in the exclusion region.

3. the step of attaching the mask on the lower electrode includes the step of attaching the mask having an arc-like shape with a certain curvature on at least a part of the outer periphery of the lower electrode; 3. The method for manufacturing a ferroelectric film-formed substrate according to claim 2, wherein the step of forming the lower electrode exposed portion includes a step of forming the lower electrode exposed portion in an arc shape with a constant curvature on at least a part of the outer periphery of the lower electrode.

4. 2. The method for manufacturing a ferroelectric film-formed substrate according to claim 1, wherein the step of polarizing the ferroelectric film includes a step of polarizing the ferroelectric film by applying a voltage between the exposed portion of the lower electrode and the upper electrode before processing the upper electrode for the device.

5. The method for manufacturing a substrate having a ferroelectric film formed thereon according to claim 1 , wherein the ferroelectric film is a piezoelectric film.

6. A ferroelectric film-formed substrate that is divided into a plurality of pieces each of which becomes a device, A substrate; a lower electrode formed on the substrate; a ferroelectric film formed on the lower electrode; an upper electrode formed on the ferroelectric film and not processed for the device; the lower electrode is connected to at least a part of the outer peripheral edge of the substrate and includes a lower electrode exposed portion on which the ferroelectric film and the upper electrode are not formed, A ferroelectric film-formed substrate, wherein the ferroelectric film has been subjected to polarization treatment.

7. A ferroelectric film-formed substrate as described in Claim 6, wherein the substrate is a substrate that is not divided into the multiple individual pieces.

8. A ferroelectric film deposition substrate as described in Claim 6, wherein the upper electrode is formed over almost the entire surface of the ferroelectric film.

9. A ferroelectric film-formed substrate as described in Claim 6, wherein the exposed lower electrode portion is formed in an exclusion region of the substrate that is not used as the device.

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