JP2011120062A - Method of manufacturing piezoelectric device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of manufacturing a piezoelectric device that separates, when manufacturing a piezoelectric compound substrate through smart-cutting, even if an ion implantation layer is formed while fixing the piezoelectric substrate at some places around the piezoelectric substrate using a fixing tool, a piezoelectric thin film from the piezoelectric substrate without fail. <P>SOLUTION: The periphery of a piezoelectric monocrystal substrate is fixed by a fixing tool, hydrogen ions are then implanted to form an ion implantation layer in the piezoelectric monocrystal layer, and an insulating film is formed thereafter on any other surface of the piezoelectric monocrystal substrate than the portions fixed by the fixing tool. A support is then bonded to the insulating film, and the piezoelectric substrate with the ion implantation layer formed thereon is heated. On the piezoelectric substrate, a micro cavity is generated along the ion implantation layer by heating and in a terminal part of the ion implantation layer, a separating surface is generated by generating a crack between a boundary between an ion implanted area and a non-implanted area and a boundary between the insulating film and a recess where the insulating film is not formed. Thus, the piezoelectric thin film can be separated without cracking the piezoelectric substrate or the support. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a piezoelectric device using a piezoelectric single crystal thin film, and more particularly to a method of manufacturing a piezoelectric device including a piezoelectric thin film and a support that supports the piezoelectric thin film.

  Currently, piezoelectric devices using single crystal materials having piezoelectricity are manufactured and used. Among them, there are SAW, F-BAR, and the like as piezoelectric devices. However, for the reason that it corresponds to a high-frequency Lamb wave device, an ultrathin film type piezoelectric device in which a piezoelectric material is further thinned has been developed. There are a plurality of methods of manufacturing a piezoelectric thin film for forming such an ultrathin film type piezoelectric device. For example, a method has been devised as shown in Patent Document 1.

The manufacturing method of the composite piezoelectric substrate described in Patent Document 1 uses a so-called smart cut method. In the smart cut method, for example, a LiTaO ₃ [lithium tantalate] substrate (hereinafter referred to as an LT substrate) or a LiNbO ₃ [lithium niobate] substrate (hereinafter referred to as an LN substrate) is used as the piezoelectric material. Thus, a composite piezoelectric substrate is generated by the following steps.

(1) By performing ion implantation on the piezoelectric substrate under predetermined conditions, an ion implantation layer is formed at a position where the piezoelectric thin film is desired to be formed from the surface of the piezoelectric substrate.
(2) A support is bonded to the piezoelectric substrate on which the ion implantation layer is formed.
(3) By heating the composite member composed of the piezoelectric substrate and the support, the piezoelectric thin film is peeled from the piezoelectric substrate with the ion implantation layer as a peeling surface.
(4) Thereafter, various pattern electrodes are formed on the piezoelectric thin film.

International Publication No. 2009/081651 Pamphlet

  FIG. 1 is a manufacturing process diagram of a conventional piezoelectric device. In the smart cut method, before performing ion implantation by irradiating the piezoelectric substrate 301 with the ion beam 321, as shown in FIG. 1A, several places around the piezoelectric substrate 301 (three places in the figure) are fixed jigs. It is fixed with 311A-fixing jig 311C. When the piezoelectric substrate 301 is fixed with a jig in this way, as shown in FIG. 1 (B), an ion implantation layer 302 is formed in the piezoelectric substrate 301 at most during ion implantation. However, the ion beam 321 is shielded in a part of the piezoelectric substrate 301 by the fixing jig 311A to the fixing jig 311C, and ions cannot be implanted, and the part becomes the ion non-implanted part 304. Therefore, as shown in FIG. 1C, when the piezoelectric thin film 303 is peeled off after the piezoelectric substrate 301 is bonded to the support 305, the ion implantation layer 302 is peeled off without any problem. However, since the non-ion-implanted portion 304 does not peel off, the piezoelectric substrate 301 is damaged together with the support 305 as shown in FIG. 1D, or the piezoelectric thin film 303 is broken halfway as shown in FIG. There was a problem that the end 301A became convex.

  Therefore, when manufacturing a piezoelectric composite substrate by the smart cut method, the present invention has a problem with the piezoelectric thin film from the piezoelectric substrate even if the ion implantation layer is formed by fixing several places around the piezoelectric substrate with a fixing jig. An object of the present invention is to provide a method for manufacturing a piezoelectric device that can be completely separated.

  The present invention relates to a method for manufacturing a piezoelectric device including a piezoelectric thin film supported by a support. This method for manufacturing a piezoelectric device includes an ion implantation process, a film formation process, a bonding process, and a separation process. In the ion implantation step, ions are implanted from the ion implantation surface of the piezoelectric substrate to form an ion implantation layer in the piezoelectric substrate. In the film forming step, an insulating film is formed on the ion-implanted surface in the other region except the region corresponding to the non-implanted portion where ions are not implanted. In the bonding step, the support is bonded to the insulating film. In the separation step, the piezoelectric thin film is peeled off and separated from the piezoelectric substrate to which the support is bonded by heating.

  When the piezoelectric substrate is fixed with a jig, at the time of ion implantation, a part of the injection surface of the piezoelectric substrate is shielded by the fixing jig, so that this portion cannot be ion-implanted and becomes an ion non-implanted portion. In this manufacturing method, an insulating film is formed in a region other than a region corresponding to an ion non-implanted portion where ions are not implanted on the ion implantation surface of the piezoelectric substrate, and the piezoelectric substrate and the support are bonded with the insulating film interposed therebetween. Thus, a composite piezoelectric body is generated. For this reason, a microcavity is generated in the ion implantation layer by heating the composite piezoelectric material. In addition, a crack is generated between the boundary between the end of the ion implantation layer and the end of the non-ion implantation portion and the boundary between the insulating film, the formation region, and the recess that is the non-insulation region. A separation plane is generated. Thereby, the piezoelectric thin film can be peeled off without causing cleavage such that the piezoelectric substrate cannot be controlled. In addition, since the piezoelectric substrate does not cause such cleavage, the substrate remaining after peeling can be reused.

  In the present invention, the film forming step includes a step of forming a resist film in a region corresponding to the non-ion-implanted portion by photolithography and an insulating film in a region other than the non-ion-implanted portion on the ion-implanted surface. And a step of removing the resist film formed in the non-ion-implanted portion. In this manufacturing method, a resist film can be accurately formed in a region corresponding to the non-ion-implanted portion by using a photolithography method. Further, in this manufacturing method, since the resist film is not formed on the surface of the insulating film, the surface of the insulating film can be kept clean. Thereby, it is possible to suppress the occurrence of bonding failure and piezoelectric device characteristic failure due to impurities such as resist residues at the bonding interface.

  In the present invention, the piezoelectric substrate is made of lithium tantalate or lithium niobate. Piezoelectric substrates made of lithium tantalate or niobate are brittle and easily cracked, but with this manufacturing method, cracks occur between the edge of the ion implantation layer and the edge of the insulating film, creating a separation surface. Is done. Accordingly, the piezoelectric substrate is not cracked when it is heated and peeled after ion implantation, and can be peeled smoothly. Further, since the peeled piezoelectric substrate can be reused, a plurality of piezoelectric devices can be manufactured from one piezoelectric substrate, and an expensive piezoelectric substrate can be saved.

  According to the present invention, when a piezoelectric composite substrate is manufactured by the smart cut method, even if several places around the piezoelectric substrate are fixed with a fixing jig to form an ion non-implanted portion, the piezoelectric substrate is peeled off without any problem. it can.

It is a manufacturing process figure of the conventional piezoelectric device. It is a flowchart which shows the manufacturing method of the thin film type piezoelectric device which concerns on the 1st Embodiment of this invention. It is a figure which shows typically the manufacturing process of the thin film type piezoelectric device formed with the manufacturing flow shown in FIG. It is a figure which shows typically the manufacturing process of the thin film type piezoelectric device formed with the manufacturing flow shown in FIG. It is a flowchart which shows the manufacturing method of the thin film type piezoelectric device which concerns on 2nd Embodiment of this invention. It is a figure which shows typically the manufacturing process of the thin film type piezoelectric device formed with the manufacturing flow shown in FIG. It is a figure which shows typically the manufacturing process of the thin film type piezoelectric device formed with the manufacturing flow shown in FIG.

  A method for manufacturing a piezoelectric device according to a first embodiment of the present invention will be described with reference to a schematic diagram of a manufacturing process of a piezoelectric device along the steps shown in the flowchart. In the following description, a surface acoustic wave device using a piezoelectric single crystal material (hereinafter referred to as a piezoelectric single crystal substrate) will be described as an example of the piezoelectric device.

  FIG. 2 is a flowchart showing a method for manufacturing a thin film piezoelectric device according to the first embodiment of the present invention. 3 and 4 are diagrams schematically showing a manufacturing process of the thin film piezoelectric device formed by the manufacturing flow shown in FIG.

First, a piezoelectric single crystal substrate 1 having a predetermined thickness is prepared. At this time, as the piezoelectric single crystal substrate 1, a multi-state substrate in which one surface 12 of the substrate is mirror-polished and a plurality of thin film type piezoelectric devices can be arranged is used. Further, as the piezoelectric single crystal substrate 1, an example is shown in which a single crystal substrate of LiTaO ₃ [lithium tantalate] (hereinafter referred to as an LT substrate), which is very brittle and cleaved and is a difficult-to-work material, is used. .

  As shown in FIG. 3A, the piezoelectric single crystal substrate 1 is held by the wafer holder 22, and a plurality of locations are fixed by a fixing jig on the outer peripheral portion of one surface 12 of the substrate (FIG. 2: S101). In the figure, as an example, the fixing jig 21A and the fixing jig 21B are attached to two locations on the outer peripheral portion of the one surface 12 of the substrate, and the piezoelectric single crystal substrate 1 is fixed. Is not limited to this. When ions are implanted into the piezoelectric single crystal substrate 1 with the ion implantation apparatus, the disk or stage on which the piezoelectric single crystal substrate 1 is set is rotated or reciprocated for the purpose of cooling or scanning of the implanted ion beam. In order to prevent the crystal substrate 1 from falling, it is pressed from the upper surface (one surface 12 of the substrate) side of the piezoelectric single crystal substrate 1.

  Then, hydrogen ions are implanted from the side of one surface 12 (corresponding to an ion implantation surface) of the substrate to form an ion implantation layer 100 in the piezoelectric single crystal substrate 1 (FIG. 2: S102). At this time, the portion to which the fixing jig 21A and the fixing jig 21B of the one surface 12 of the piezoelectric single crystal substrate 1 are attached is shielded by the fixing jigs 21A and 21B. 14A and 14B.

When an LT substrate is used as the piezoelectric single crystal substrate 1 and hydrogen ion implantation is performed at an implantation energy of 150 keV and a dose (ion implantation density) of 1.0 × 10 ¹⁷ atoms / cm ² , the depth from one surface 12 of the substrate is increased. An ion implantation layer 100 in which hydrogen ions are distributed at a position of about 1 μm is formed. In addition to the LT substrate, an LN substrate, an LBO (Li ₂ B ₄ O ₇ ) substrate, or a langasite (La ₃ Ga ₅ SiO ₁₄ ) substrate may be used as the piezoelectric single crystal substrate 1. Ion implantation is performed under the corresponding conditions. Note that these substrates are characterized by high brittleness and easy cleavage and cracking starting from cracks. In addition, the implanted ions may be changed to helium ions, argon ions, or the like depending on the type of substrate.

  Next, the insulating layer is patterned by a lift-off method.

  As shown in FIG. 3 (C), on one surface 12 of the piezoelectric single crystal substrate 1, a portion (an area corresponding to the non-ion-implanted portions 14A and 14B) to which the fixing jig 21A and the fixing jig 21B are attached is provided. A resist film 15A and a resist film 15B are formed by photolithography (FIG. 2: S103). Since the photolithography method can perform patterning with high accuracy, a pattern having substantially the same shape as the non-ion-implanted portion can be formed.

As shown in FIG. 3D, an insulating film 32 is formed on one surface 12 of the piezoelectric single crystal substrate 1 (FIG. 2: S104). As the material of the insulating film _{32, SiO 2, SiN, Al} 2 O 3, magnesia, etc., it may be formed by using a sputtering or CVD. By forming the pattern of the insulating film 32 so that only the non-ion-implanted portion is concave, the stability in the piezoelectric thin film separation step described later can be increased.

  As shown in FIG. 3E, the resist films 15A and 15B and the insulating film 32 on the resist films 15A and 15B are removed by immersion in a resist stripping solution (FIG. 2: S105). As a result, the insulating film 32 is formed on a portion of the surface 12 of the piezoelectric single crystal substrate 1 where the resist film 15A and the resist film 15B are not formed (region corresponding to the ion implantation layer 100).

  In this way, by forming the resist films 15A and 15B and the insulating film 32 on the one surface 12 of the piezoelectric single crystal substrate 1, a resist film is not formed on the surface of the insulating film 32, and a bonding process described later. In this case, the cleanliness of the joint surface can be maintained. Thereby, it is possible to suppress the occurrence of bonding failure and piezoelectric device characteristic failure due to impurities such as resist residues at the bonding interface.

  The insulating film 32 is required to have a thickness such that the recesses 16A and the recesses 16B, which are non-forming regions of the insulating film from which the resist film 15A and the resist film 15B are removed, are not in contact with the support in the bonding process described later. is there.

  Subsequently, polishing is performed to planarize the surface of the insulating film 32 (FIG. 2: S106). As will be described later, the surface of the insulating film 32 is preferably mirror-polished in preparation for direct bonding such as activation bonding to the support.

A support 30 is prepared. As a material for the support 30, LT (LiTaO ₃ ), LN (LiNbO ₃ ), Si, glass, alumina, or the like is used. Then, as shown in FIG. 3F, the insulating film 32 formed on the one surface 12 of the piezoelectric single crystal substrate 1 and the support 30 are directly bonded in a vacuum using a cleaning bonding technique (FIG. 3F). 2: S107). Clean bonding is a bonding method in which Ar ions or the like are irradiated in a vacuum and the bonding surfaces are activated, and does not require heating. In such a joining method, since bonding can be performed at room temperature, even if a support substrate having a linear expansion difference with the piezoelectric film is used, warping does not occur after joining, and a heating process for removing hydrogen is not required as in hydrophilic bonding. For this reason, it is preferable because piezoelectric deterioration of the piezoelectric substrate and generation of stress due to a difference in linear expansion between the support and the piezoelectric substrate are not a problem.

  As described above, since the insulating film 32 is not patterned in the recesses 16A and 16B, the piezoelectric single crystal substrate 1 and the support 30 are not bonded in the recesses 16A and 16B.

  In addition, there is a high possibility that organic substances and metal-based impurities are present at the bonding interface at the bonded surfaces when particles, slurry residue before mirror surface treatment before bonding, activation treatment, and hydrophilic treatment are performed. However, in this process, since an insulating film is formed on the piezoelectric substrate and the direct bonding interface does not come into contact with the piezoelectric substrate, the characteristic failure of the piezoelectric device due to impurities and particles can be suppressed.

  Next, as shown in FIG. 4A, the composite piezoelectric material obtained by bonding the support 30 and the piezoelectric single crystal substrate 1 on which the insulating film 32 is formed is heated, so that the ion implantation layer 100 is separated from the release surface. The peeling is performed (FIG. 2: S108). Thereby, the composite piezoelectric substrate 2 composed of the support 30, the insulating film 32 and the piezoelectric thin film 10 is separated from the piezoelectric single crystal substrate (LT substrate) 1 (not shown). At this time, the heating temperature can be lowered by heating in a reduced pressure atmosphere.

  As described above, the LT substrate is highly brittle and the cleavage is likely to be extended starting from cracks. However, the ion-implanted layer 100 (having a depth of 1 μm from the surface of the LT substrate) 100 into which hydrogen ions are implanted by the above-described process generates microcavities along the surface by heating. When the thickness of the piezoelectric thin film to be separated is 5 μm or less, the boundary 100A between the end of the ion implantation layer 100 and the ion non-implant 14A, the boundary 32A between the insulating film 32 and the recess 16A, and the ion implantation Cracks are generated between the boundary portion 100B between the end portion of the layer 100 and the non-ion-implanted portion 14B and the boundary portion 32B between the insulating film 32 and the recess 16B, thereby generating a separation surface. Thus, the composite piezoelectric substrate 2 including the piezoelectric thin film 10 having a thickness of 1 μm and a piezoelectric single crystal substrate (LT substrate) (not shown) are separated. According to the experiment, when the thickness of the LT substrate to be separated was 5 μm, the separation surface was generated within a range of 2 μm from the boundary portion 100B and the boundary portion 32B.

  Next, the surface 13 of the piezoelectric thin film 10 thus peeled and the surface of the piezoelectric single crystal substrate from which the piezoelectric thin film 10 has been peeled are polished by a CMP (Chemical Mechanical Planarization) process or the like to obtain a surface roughness Ra. Is flattened so as to be 1 nm or less (FIG. 2: S109). Thereby, the characteristic of a piezoelectric device can be improved.

  The piezoelectric single crystal substrate from which the piezoelectric thin film 10 is separated is reused as a material for producing another composite piezoelectric substrate 2.

  Subsequently, the composite piezoelectric substrate 2 is subjected to a substrate heating process for restoring the piezoelectricity (FIG. 2: S110). Heating at 450 ° C. or higher is desirable in order to relieve the distortion of crystals received by ion implantation. By this step, the crystal that has been distorted by the hydrogen element remaining in the LT single crystal at the time of ion implantation recovers its crystallinity due to the removal of the implanted hydrogen ion, and Li also returns to the original polarized site. By doing so, the piezoelectricity is restored.

  Next, as shown in FIG. 4C, upper surface electrode patterns such as the upper electrode 60 and the pad electrode 61 are formed on the surface 13 of the piezoelectric thin film 10 (FIG. 2: S111). The electrode material may be selected in accordance with required device characteristics.

  Next, as shown in FIG. 4D, bumps 90 are formed on the pad electrodes 61 (FIG. 2: S112). Then, as shown in FIG. 4E, the multi-state composite piezoelectric substrate 2 is cut to cut out individual thin film piezoelectric devices (FIG. 2: S113). A surface wave device can be manufactured by such a manufacturing process.

  Next, a method for manufacturing a piezoelectric device according to a second embodiment of the present invention will be described with reference to the schematic diagram of the manufacturing process of the piezoelectric device along the steps shown in the flowchart. In the following description, a thin film piezoelectric device for F-BAR using a piezoelectric single crystal substrate will be described as an example of the piezoelectric device.

  FIG. 5 is a flowchart showing a method for manufacturing a thin film piezoelectric device according to the first embodiment of the present invention. 6 and 7 are diagrams schematically showing a manufacturing process of the thin film piezoelectric device formed by the manufacturing flow shown in FIG.

  In the piezoelectric device manufacturing method according to the second embodiment, the steps (steps S201 to S202) until the ion implantation layer 100 is formed are the same as steps S101 to S102 of the piezoelectric device manufacturing method according to the first embodiment. is there.

  That is, as shown in FIG. 3A, the piezoelectric single crystal substrate 1 is held by the wafer holder 22, and a plurality of locations are fixed by a fixing jig on the outer peripheral portion of one surface 12 of the substrate. In the drawing, as an example, the fixing jig 21A and the fixing jig 21B are attached to two locations on the outer peripheral portion of the one surface 12 of the substrate, and the piezoelectric single crystal substrate 1 is fixed (FIG. 5: S201).

  Then, hydrogen ions are implanted from the side of one surface 12 (corresponding to the ion implantation surface) of the substrate to form the ion implantation layer 100 in the piezoelectric single crystal substrate 1 (FIG. 5: S202).

  As shown in FIG. 6A, a lower electrode 20, a pad electrode 51A, and a pad electrode 51B having a predetermined thickness are formed on one surface 12 of the piezoelectric single crystal substrate 1 after the ion implantation layer 100 is formed (FIG. 5). : S203). The electrode material may be Mo, W, Al, Ni, or a multilayer structure thereof in accordance with required device characteristics. Moreover, it is good to form using EB vapor deposition, sputtering, CVD, etc. according to the kind of electrode material.

As shown in FIG. 6A, a sacrificial layer 40 is formed on the lower electrode 20 (FIG. 5: S204). For the sacrificial layer 40, it is preferable to select a material capable of selecting an etching gas or an etchant that can obtain selectivity with the lower electrode when the sacrificial layer is removed in a process described later. Metals such as Ni, Cu, and Al, insulating films and organic films such as SiO ₂ , ZnO, and PSG (phosphosilicate glass) can be used as the sacrificial layer material. The sacrificial layer 40 may be formed by EB vapor deposition, sputtering, CVD, or the like depending on the type of material.

  Next, a membrane support layer 33 is formed on one surface 12 of the piezoelectric single crystal substrate 1. The membrane support layer 33 forms a pattern so that the recesses 18A and the recesses 18B are not in contact with the support when bonded to the support described later. The membrane support layer 33 also serves as the insulating film 32 in the first embodiment.

  The membrane support layer 33 is formed in the same manner as Steps S103 to S105 in the first embodiment. That is, as shown in FIG. 6 (B), a portion (an area corresponding to the non-ion-implanted portions 14A and 14B) where the fixing jig 21A and the fixing jig 21B are attached on one surface 12 of the piezoelectric single crystal substrate 1. Then, a resist film 17A and a resist film 17B are formed by photolithography (FIG. 5: S205).

  As shown in FIG. 6C, a membrane support layer (insulating film) 33 is formed on one surface 12 of the piezoelectric single crystal substrate 1 (FIG. 5: S206). As shown in FIG. 3D, the resist film 17A, the resist film 17B, and the membrane support layer 33 on the resist films 17A and 17B are removed by immersion in a resist stripping solution (FIG. 5: S207). As a result, the membrane support layer (insulating film) 33 was formed on the portion of the surface 12 of the piezoelectric single crystal substrate 1 where the resist film 17A and the resist film 17B were not formed (region corresponding to the ion implantation layer 100). It will be.

As the material of the membrane-supporting layer _{33, SiO 2, SiN, Al} 2 O 3, magnesia, etc., it may be formed by using a sputtering or CVD. Further, the stress of the thin film, which causes film peeling, should be kept as low as possible.

  Next, the surface of the membrane support layer 33 is planarized by CMP processing or the like (FIG. 5: S208).

A support 30 is prepared. As a material for the support 30, LT (LiTaO ₃ ), LN (LiNbO ₃ ), Si, glass, alumina, or the like is used. Then, as shown in FIG. 6E, the membrane support layer 33 and the support 30 are directly bonded in a vacuum using a cleaning bonding technique (FIG. 5: S209). Since the membrane support layer 33 is not formed in the recesses 18A and 18B from which the resist film 17A and the resist film 17B have been removed, the piezoelectric single crystal substrate 1 and the support 30 are not joined in the recesses 18A and 18B.

  As shown in FIG. 7A, the substrate on which the piezoelectric single crystal substrate 1 and the support 30 are bonded is heated to perform separation using the ion implantation layer 100 as a separation surface (FIG. 5: S210). As described with reference to FIG. 4A, in the piezoelectric single crystal substrate 1, when the thickness of the piezoelectric thin film to be separated is 5 μm or less, the boundary portion between the end portion of the ion implantation layer 100 and the non-ion implantation portion 14A. 100A and the boundary 32A between the insulating film 32 and the recess 16A, the boundary 100B between the end of the ion implantation layer 100 and the ion non-implanted portion 14B, and the boundary 32B between the insulating film 32 and the recess 16B. Cracks are generated in the middle and a separation surface is generated. Thereby, the composite piezoelectric substrate 3 can be generated stably. Further, because of the membrane structure, the region corresponding to the non-ion-implanted portion becomes concave and is attached to the support 30 even when the membrane support layer 33, the lower electrode 20, the pad electrode 51A, the pad electrode 51B, and the sacrificial layer 40 are present. If they are not matched, neither the piezoelectric single crystal substrate 1 nor the support 30 will have a problem of cracking or chipping.

  Next, as shown in FIG. 7B, the surface 13 of the peeled piezoelectric thin film 10 and the surface of the piezoelectric single crystal substrate (not shown) from which the piezoelectric thin film 10 has been peeled are polished by CMP or the like to roughen the surface. Planarization is performed so that Ra is 1 nm or less (FIG. 5: S211).

  The piezoelectric single crystal substrate 1 from which the piezoelectric thin film 10 is separated is reused as a material for producing another composite piezoelectric substrate 3.

  Subsequently, the composite piezoelectric substrate 3 is subjected to a substrate heating process for restoring the piezoelectricity (FIG. 5: S212).

  Next, upper surface electrode patterns such as the upper electrode 50 and the pad electrodes 52A and 52B are formed on the surface 13 of the piezoelectric thin film 10 (FIG. 5: S213). As with the lower electrode 20, the electrode material may be selected according to the required device characteristics.

  Subsequently, a resist film (not shown) is formed on the surface of the piezoelectric thin film 10 on which the upper electrode 50 is formed (FIG. 5: S214). Then, using a photolithography technique, an etching window for removing the sacrificial layer is formed in the resist film as shown in FIG. 5B (FIG. 5: S215). At the same time, a lower electrode wiring extraction window is formed.

  Next, the sacrificial layer 40 is removed by introducing an etching gas or an etchant from the etching window (FIG. 5: S216). Thereby, the space in which the sacrificial layer 40 corresponding to the region in which the lower electrode 20 and the upper electrode 50 of the single thin film piezoelectric device are formed becomes the void layer 80. It is preferable to select a wet etching solution or etching gas that does not affect the membrane support layer 33, the upper electrode 60, and the lower electrode 20.

  After removing the sacrificial layer 40, the resist film is removed (FIG. 5: S217).

  Next, as shown in FIG. 7C, bumps 91 are formed on the pad electrodes 52A and 52B (FIG. 5: S218). Then, as shown in FIG. 7D, the multi-state composite piezoelectric substrate 3 is cut to cut out individual thin film piezoelectric devices (FIG. 5: S219). By such a manufacturing process, an F-BAR type thin film piezoelectric device can be manufactured.

  In addition, the manufacturing method of the piezoelectric device which concerns on embodiment of this invention is applicable to various piezoelectric devices other than F-BAR and a surface wave device. For example, it can be applied to a piezoelectric vibration motor, a gyro, and the like.

  In addition, although the example which forms an insulating film in the piezoelectric single crystal substrate side was shown, not only this but an insulating film is formed in a support body side, and an insulating film is formed in the area | region equivalent to the ion implantation layer in the back surface of a piezoelectric single crystal substrate May be joined.

  In addition, an insulating film may be formed on the entire back surface of the piezoelectric single crystal substrate, and the insulating film may be removed by etching for a region corresponding to the non-ion implanted portion.

1-piezoelectric single crystal substrate, 2,3-composite piezoelectric substrate, 10-piezoelectric thin film, 14A, 14B-ion non-implanted portion, 15A-15B-resist film, 16A, 16B, 18A, 18B-recess, 20-lower electrode 21A, 21B-fixing jig, 30-support, 32-insulating film, 33-membrane supporting layer (insulating film), 40-sacrificial layer, 51A, 51B, 61A, 61B-pad electrode, 60-upper electrode, 70-resist film, 71-etching window, 80-gap layer, 90,91-pump, 100-ion implantation layer

Claims (3)

A method of manufacturing a piezoelectric device comprising a piezoelectric thin film supported by a support,
An ion implantation step of implanting ions from an ion implantation surface of the piezoelectric substrate to form an ion implantation layer in the piezoelectric substrate;
A film forming step of forming an insulating film in a region other than a region corresponding to an ion non-implanted portion where ions are not implanted on the ion implantation surface;
A bonding step of bonding a support to the insulating film;
A separation step of peeling and separating the piezoelectric thin film from the piezoelectric substrate to which the support is bonded by heating;
A method for manufacturing a piezoelectric device comprising: The film forming step includes
Forming a resist film in a region corresponding to the non-ion-implanted portion by a photolithography method;
Forming an insulating film in a region other than the non-ion-implanted portion of the ion-implanted surface;
Removing the resist film formed on the non-ion-implanted portion;
The manufacturing method of the piezoelectric device of Claim 1 provided with these.   The method for manufacturing a piezoelectric device according to claim 1, wherein the piezoelectric substrate is made of lithium tantalate or lithium niobate.

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