JP5040403B2 - Piezoelectric thin film vibration device and manufacturing method thereof - Google Patents

Description

  The present invention relates to a piezoelectric thin film vibration device having a thin film vibration body that is floated on a support substrate with a gap therebetween, and more specifically, a piezoelectric thin film vibration device having an improved shape of a thin film vibration body made of a thin film laminate, and the same It relates to a manufacturing method.

  Conventionally, a piezoelectric thin film resonator using a piezoelectric thin film is known to constitute an oscillator or a resonator. In the piezoelectric thin film resonator, a thin film vibrating body using a piezoelectric thin film is arranged in a state of being floated with a gap from the support substrate. Therefore, compared with a piezoelectric resonator using a piezoelectric ceramic chip or the like, it is possible to achieve a higher frequency and a thinner thickness.

  An example of a piezoelectric thin film vibration device using this type of piezoelectric thin film is disclosed in Patent Document 1 below. FIG. 14 is a perspective view showing a piezoelectric thin film vibration device disclosed in Patent Document 1. As shown in FIG.

  The piezoelectric thin film vibration device 501 has a support substrate 502. A thin-film vibrating body 503 having a rectangular planar shape is disposed in a state of being floated from the upper surface of the support substrate 502 at a distance. The thin film vibrator 503 includes a base 504 made of Si, a lower electrode 505 stacked on the base 504, a piezoelectric thin film 506 stacked on the lower electrode 505, and an upper electrode 507 stacked on the piezoelectric thin film 506. Have

  In FIG. 14, the base 504, the piezoelectric thin film 506, and the like are shown to be relatively thick, but actually, they are thin films having a film thickness of about 0.1 to 10 μm. That is, the thin film vibrator has a structure in which a plurality of thin films are stacked. The piezoelectric thin film 506 is polarized so as to vibrate in the spreading vibration mode when an alternating voltage is applied from the lower electrode 505 and the upper electrode 507. That is, the thin-film vibrating body 503 is a piezoelectric resonator that uses a spreading vibration mode of a rectangular planar vibrating body.

  In order to float the thin film vibrator 503 from the upper surface of the support substrate 502, a pair of side surfaces of the base 503 are connected to inclined support portions 508 and 509, respectively. The outer ends of the inclined support portions 508 and 509 are connected to support portions 510 and 511 fixed on the support substrate 502.

  On the other hand, the following Patent Document 2 discloses a piezoelectric thin film resonator and a manufacturing method thereof shown in FIG. Here, the piezoelectric thin film resonator 601 includes a thin film vibrating body 604 that is floated via a gap 603 on a support substrate 602. The thin-film vibrating body 604 includes a piezoelectric thin film 605, a lower electrode 606 stacked on the lower surface of the piezoelectric thin film 605, and an upper electrode 607 provided on the upper surface. The portion of the piezoelectric thin film 605 sandwiched between the lower electrode 606 and the upper electrode 607 is a resonance portion that resonates due to the piezoelectric effect.

A dielectric film 608 is provided on the lower surface of the lower electrode 606. In manufacturing the piezoelectric thin film resonator 601, first, a sacrificial layer is formed at a position where the gap 603 is disposed on the support substrate. Next, the dielectric film 608, the lower electrode 606, the piezoelectric thin film 605, and the upper electrode 607 are sequentially formed by a thin film forming method, and then the sacrificial layer is removed.
JP-A-8-186467 JP 2006-166419 A

  When a plurality of thin films are sequentially formed by a thin film forming method and laminated to obtain a thin film vibrating body, each thin film has a film stress in the plane direction as an internal stress. That is, each thin film has, as a film stress, a stress that tends to shrink in the plane direction or a compressive stress that tries to spread in the plane direction as an internal stress. Due to the relationship between the film stress and the film thickness of the plurality of thin films, the thin film vibrator may bend.

  For example, in the piezoelectric resonator 601, the dielectric film 608, the lower electrode 606, the piezoelectric thin film 605, and the upper electrode 607 are formed in a state having film stress that becomes tensile stress or compressive stress. For this reason, the thin-film vibrating body 604 that is configured to float from the support substrate 602 may warp due to the relationship between the film stress and the film thickness of these thin films. In particular, in the thin film vibrator 604 portion, when warping occurs so that the central portion is convex upward, the corner portion of the rectangular thin film vibrator 604 is a support substrate as schematically shown in a perspective view in FIG. 602 may come into contact.

  In addition, in the thin film vibrator 604 that tends to come into contact with the support substrate 602 and needs to be lifted from the support substrate 602, not only the corner portion but also other portions such as the central portion of the thin film vibrator 604 are used. However, it should not be in contact with the support substrate 602. When the piezoelectric thin film vibrating body 604 comes into contact with the support substrate 602, vibration characteristics and electrical characteristics using the spread vibration mode are greatly impaired.

  In addition, when exposed to a process such as reflow soldering when mounting the piezoelectric thin film resonator on the mounting substrate, the thin film vibrator is also affected by the difference in thermal expansion coefficient of the material constituting each thin film. Warpage sometimes occurred. Therefore, the warp caused by the relationship between the film stress and the film thickness is further enlarged, and the vibration characteristics may be greatly impaired.

  An object of the present invention is to provide a piezoelectric thin-film vibration device including a thin-film vibrating body portion in which a plurality of thin films are sequentially stacked by a thin-film forming method, in view of the above-described state of the prior art. Accordingly, it is an object of the present invention to provide a piezoelectric thin-film vibration device and a method for manufacturing the same that can reliably obtain the desired vibration characteristics and electrical characteristics.

According to the present invention, the support substrate and the support substrate are arranged so as to be floated from the upper surface of the support substrate, and are formed of a stacked film formed by stacking a plurality of thin films formed by a thin film forming method. Are connected to the rectangular thin film vibrator and a part of the rectangular first and second sides of the thin film vibrator that are opposed to each other, and are fixed to the support substrate. The thin-film vibrator includes a piezoelectric thin film, a first excitation electrode laminated on the lower surface of the piezoelectric thin film, a second excitation electrode laminated on the upper surface of the piezoelectric thin film, and the first , The first and second strip-shaped tensile films arranged so as to extend along the second side, and the thin film vibrating body as one thin film of the plurality of thin films, the first and second films The film is applied to the central region between the first and second stripe regions extending along the side. There has at least a stress adjusting film is a compressive stress, the thin film vibrator first, so that the center in the direction connecting the second side warps in a convex upwardly, and, in the first, second sides A plurality of thin film vibrators constituting the thin film vibrating body are positioned upward as they go outward from the first and second support portions, and protrude downwardly on the first and second sides. The relationship between the film stress and the film thickness is set, whereby the first and second support portions are located at the lowest position on the first and second sides, and the first and second support portions A piezoelectric thin film vibration device is provided in which the thin film vibration body is warped so that the first and second support portions are located at the lowest position in the direction connecting the two.

  In the present invention, in the direction in which the first and second support portions are located at the lowest position on the first and second sides of the thin film vibrator and the first and second support portions are connected, The thin film vibrator needs to be warped so that the second support portion is located at the lowest position. Means for realizing such a warped shape of the thin film vibrator is as follows: Although not particularly limited, it is particularly preferable that the first and second support portions are located at the lowest position along the first and second sides, and the first and second support portions are connected to each other. In the above, the film stresses of the plurality of thin films constituting the thin film vibrating body are formed such that the thin film vibrating body is warped so that the first and second support portions are located at the lowest position. And a film thickness relationship is set. In this case, the thin film vibrator can be reliably warped as described above only by adjusting the relationship between the film stress and the film thickness of each thin film constituting the thin film vibrator.

In the piezoelectric thin film vibration equipment of the present invention, the thin film vibrator the first, in the above second side first, the thin film vibration from the second supporting portion so as to be positioned above him to go outside The relationship between the film stress and the film thickness of the plurality of thin films constituting the thin film vibrating body is set so that the body warps downwards in the first and second sides. Therefore, the thin-film vibrating body is positioned upward on the first and second sides as it goes outward from the first and second support portions only by adjusting the relationship between the film stress and film thickness of the plurality of thin films. As a result, the corner portion of the rectangular thin film vibrator can be reliably moved away from the upper surface of the support substrate. Therefore, contact of the corner portion with the support substrate can be reliably prevented.

In the piezoelectric thin film vibration device according to the present invention, the film stresses of the plurality of thin films in the portions extending along the first and second sides so that the thin film vibrating body warps downward in the first and second sides. In order to set the relationship between the film thickness and the film thickness, a tensile film whose film stress is tensile stress is formed so as to extend along the first and second sides. In this case, by forming the tensile film, the thin-film vibrating body can be reliably warped downward on the first and second sides.

  The piezoelectric thin film vibration device according to the present invention preferably includes a temperature characteristic adjusting film made of a material having a frequency temperature coefficient opposite in polarity to the frequency temperature coefficient of the piezoelectric thin film. By providing the temperature characteristic adjusting film, the absolute value of the frequency temperature coefficient of the piezoelectric thin film vibration device can be reduced. Accordingly, it is possible to reduce the change in characteristics due to a temperature change.

In the present invention, before Symbol thin film vibrator, the one thin film of said plurality of thin film, the first, first extending along the second side, the film stress in the central region between the second stripe region A stress adjusting film that is a compressive stress is further provided, whereby the center of the thin film vibrator is curved upward in the direction connecting the first and second sides, and at the first and second sides. The plurality of thin-film vibrators constituting the thin-film vibrating body are positioned upward as they go outward from the first and second support components and warp downward on the first and second sides. The relationship between film stress and film thickness is set. More preferably, the stress adjustment film is also a temperature characteristic adjustment film made of a material having a frequency temperature coefficient opposite to the frequency temperature coefficient of the piezoelectric thin film.

  In the present invention, it is preferable that the first excitation electrode laminated on the lower surface of the piezoelectric thin film among the first and second excitation electrodes laminated via the piezoelectric thin film is the second excitation electrode. It leads to the outside of the electrode.

The method of manufacturing a piezoelectric thin film vibration device according to the present invention includes a step of preparing a support substrate, a step of forming a sacrificial layer made of a material that can be lost by applying a solvent or energy on the support substrate, and covering the sacrificial layer As described above, the rectangular thin-film vibrating body is fixed to the support substrate at a part of the first and second sides of the rectangular shape facing each other, so that the first and second support portions are provided. And in the first and second sides where the first and second support portions are provided, the first and second support portions are located at the lowest position, and the first and second support portions Forming the thin-film vibrator so that the thin-film vibrator is warped so that the first and second support portions are located at the lowest position in the direction of connecting the sacrificial layer, and the sacrificial layer is eliminated by solvent or by applying energy, Thereby, the thin film vibrator and the support portion A step of providing a gap therebetween, and in forming the thin film vibrator, at least a piezoelectric thin film, a first excitation electrode laminated on the lower surface of the piezoelectric thin film, and a second laminated on the upper surface of the piezoelectric thin film. The excitation electrode , the striped first and second tensile films arranged so as to extend along the first and second sides, and the thin film vibrating body as one thin film of the plurality of thin films, A plurality of thin films including at least a stress adjusting film whose film stress is a compressive stress is sequentially formed by a thin film forming method in a central region between the first and second stripe regions extending along the first and second sides. In the direction in which the thin-film vibrating body connects the first and second sides, the center protrudes upward and the first and second sides go outward from the first and second support portions. Is located on the upper side and protrudes downward on the first and second sides. So that the features a Rukoto relationship between a plurality of thin film stress and film thickness constituting the thin film vibrator has been set.

In the production how according to the present invention, in the thin film vibrator, the first and the second sides, first and second support portions is located lowermost, and the first, second support In forming each thin film of the thin-film vibrator, the thin-film vibrator is warped so that the first and second support portions are located at the lowest position in the direction connecting the portions. The relationship between the film stress and the film thickness of each thin film of the thin film vibrator is set. In this case, the thin film vibrator can be reliably warped as described above only by adjusting the relationship between the film stress and the film thickness of each thin film constituting the thin film vibrator.

In the production how according to the present invention, in the step of forming each thin film of the thin film vibrator, the first and the second sides, the first, as the go outward from the second supporting portion and the Film stresses and film thicknesses of a plurality of thin films constituting the thin-film vibrator so that the thin-film vibrator is warped downward in the first and second sides so that the thin-film vibrator is positioned above Is set. Therefore, the thin-film vibrating body is positioned upward on the first and second sides as it goes outward from the first and second support portions only by adjusting the relationship between the film stress and film thickness of the plurality of thin films. As a result, the corner portion of the rectangular thin film vibrator can be reliably moved away from the upper surface of the support substrate. Therefore, contact of the corner portion with the support substrate can be reliably prevented.

In the manufacturing method of the present invention, the film stress and the film thickness of the plurality of thin films in the portion extending along the first and second sides so that the thin film vibrating body warps downward on the first and second sides. In order to set the relationship, a tensile film whose film stress is tensile stress is formed so as to extend along the first and second sides. In this case, by forming the tensile film, the thin-film vibrating body can be reliably warped downward on the first and second sides.

  In the method for manufacturing a piezoelectric thin film vibration device according to the present invention, preferably, at the time of forming the thin film vibrating body, a frequency having a polarity opposite to a frequency temperature coefficient of the piezoelectric thin film is used as at least one of the plurality of thin films. A temperature characteristic adjusting film made of a material having a temperature coefficient is formed. By providing the temperature characteristic adjusting film, the absolute value of the frequency temperature coefficient of the piezoelectric thin film vibration device can be reduced. Accordingly, it is possible to reduce the change in characteristics due to a temperature change.

In the manufacturing method of the piezoelectric thin film vibrator according to the present invention, upon formation of the previous SL thin vibrating body, as one of the thin film of the plurality of thin film, the first, first extending along the second side, the second The method further includes the step of forming a stress adjustment film whose film stress is a compressive stress in the central region between the stripe-shaped regions, whereby the center of the thin film vibrator protrudes upward in the direction connecting the first and second sides. It warps and is located upward as it goes outward from the first and second support parts on the first and second sides, and protrudes downward on the first and second sides. In addition, the relationship between the film stress and the film thickness of a plurality of thin films constituting the thin film vibrator is set.

  In the method for manufacturing a piezoelectric thin film vibration device according to the present invention, the stress adjustment film is also a temperature characteristic adjustment film made of a material having a frequency temperature coefficient opposite in polarity to the frequency temperature coefficient of the piezoelectric thin film.

  In the method of manufacturing the piezoelectric thin film vibration device according to the present invention, in forming the thin film vibrating body, the first excitation electrode and the piezoelectric thin film are formed, and then the first excitation electrode is opposed to the first thin film through the piezoelectric thin film. The second excitation electrode is formed so as not to reach the outside of the first excitation electrode.

  The thin film forming method for forming the plurality of thin films is not particularly limited, and a known thin film forming method such as sputtering, vapor deposition, ion plating, or plating can be used.

  In the piezoelectric thin-film vibration device according to the present invention, the thin-film vibrator formed by laminating a plurality of thin films formed by the thin-film forming method is arranged so as to float from the upper surface of the support substrate. The first and second support portions that are fixed to the support substrate are located at the lowest positions on the first and second sides, and the first and second support portions are connected in the direction connecting the first and second support portions. The thin-film vibrating body is warped so that the second support portion is located at the lowest position. Accordingly, the corner portion of the rectangular thin film vibrator is positioned above the first and second support portions. In addition, the central portion of the rectangular thin film vibrator is also positioned above the first and second support portions.

  In the conventional piezoelectric thin film vibration device, the rectangular thin film vibration body tends to contact the support substrate mainly at the corner portion. On the other hand, according to the present invention, since the thin film vibrating body is warped so that the corner portion is located above, it is possible to prevent the thin film vibrating body from contacting the support substrate.

  Even if the thin-film vibrating body is designed to be flat, it may protrude downward due to variations in film forming conditions. In that case, there is a possibility that the central portion of the thin-film vibrating body comes into contact with the support substrate. However, in the present invention, as described above, the thin film vibrator is warped so that the central portion of the rectangular thin film vibrator is also located above the first and second support portions. Therefore, the contact of the central portion of the thin film vibrator with the support substrate can also be reliably prevented.

  Therefore, according to the piezoelectric thin film vibration device according to the present invention, it is possible to reliably obtain the desired vibration characteristics and electrical characteristics.

  In particular, due to the relationship between the film stress and the film thickness of each thin film when the thin film vibrating body was formed, the corner part and the central part were not only difficult to contact the support substrate, but were also exposed to a heating process such as reflow soldering. At this time, even if a distortion due to a difference in thermal expansion coefficient between the thin films occurs, the thin film vibrating body can be prevented from contacting the support substrate. As a result, the intended vibration characteristics and electrical characteristics can be more reliably exhibited.

  In the manufacturing method according to the present invention, in forming the thin film vibrator, a plurality of thin films are sequentially formed by the thin film forming method. In the first and second sides where the first and second support portions are connected, The thin film vibrator is warped so that the first and second support portions are located at the lowest position and the first and second support portions are located at the lowest position in the direction connecting the first and second support portions. Thus, since the thin film vibrator is formed, the contact of the corner portion and the center portion of each thin film vibrator with the support substrate can be reliably suppressed. In addition, even when heat is applied during the assembly process or actual use, the thin film vibrating body does not easily contact the support substrate due to distortion due to the difference in thermal expansion coefficient of each thin film. That is, it is possible to provide the piezoelectric thin film vibration device of the present invention that makes it possible to reliably obtain the desired vibration characteristics and electrical characteristics.

  Hereinafter, the present invention will be clarified by describing specific embodiments of the present invention with reference to the drawings.

  FIG. 1 is a cross-sectional view showing a thin-film vibrating body portion of the piezoelectric thin-film vibration device according to the first embodiment of the present invention, and FIG. 2A is a plan view of the piezoelectric thin-film vibration device. In addition, the cross section shown by FIG. 1 is a cross section in alignment with the dashed-dotted line AA of FIG.

  The thin-film vibrating body 2 of the piezoelectric thin-film vibration device 1 according to the present embodiment is a portion arranged in a state of being floated from the support substrate 3 as will be described later. The thin film vibrator 2 includes a temperature characteristic adjustment film 4, a first excitation electrode 5, a piezoelectric thin film 6, a second excitation electrode 7, a stress relaxation film 8, a temperature characteristic adjustment film 9, and tensile films 10, 11 from the bottom layer. It has a laminated structure. Each of these films is formed by sequentially forming a film by a thin film forming method. Details of each of these thin films are as follows.

Temperature characteristic adjustment film 4: consists SiO _2, film thickness 1.7 [mu] m, the film stress is a compression stress, the value is -180MPa.

  1st excitation electrode 5: It consists of Pt, and the film thickness is 0.1 micrometer.

  Second excitation electrode 7: made of Pt and having a film thickness of 0.1 μm. The first and second excitation electrodes 5 and 7 are very thin, and the influence of the film stress of the excitation electrodes 5 and 7 on the warp can be ignored.

  Piezoelectric thin film 6: made of AlN, the polarization direction is the thickness direction, the film thickness is 1.6 μm, the film stress is the compressive stress, and the value is −80 MPa.

  Stress relaxation film 8: made of AlN, film thickness is 0.8 μm, film stress is tensile stress, value is 100 MPa.

Temperature characteristic adjustment film 9 made of SiO _2, film thickness 3.3 [mu] m, the film stress is a compression stress, the value is -180MPa.

  Tensile films 10, 11: made of AlN, the film thickness is 0.8 μm, the film stress is tensile stress, and the value is 100 MPa.

  The film stress is a thin film such as the piezoelectric thin film 6, the stress relaxation film 8, the tensile films 10 and 11, and the temperature characteristic adjusting films 4 and 9, and a thin film having a certain thickness is formed by a thin film forming method such as sputtering. In this case, each thin film refers to the stress in the surface direction that the thin film has as its own internal stress.

  However, it is difficult to measure the film stress in each thin film constituting the thin film vibrating body. Therefore, as will be described later in detail, the above-described film stress values are measured and calculated in a state where each thin film is formed on a circular Si substrate. Since the thin film vibrating body of the piezoelectric thin film vibrating apparatus is arranged in a state of being floated from the support substrate, the obtained film stress value is not the film stress itself in the thin film constituting the thin film vibrating body. However, these values correspond to the film stress in the thin film constituting the thin film vibrating body. That is, the relative relationship of these values, that is, the magnitude relationship including the sign, is the same as the relative relationship of the film stress in each thin film constituting the actual thin film vibrator, and therefore in the thin film vibrator formed by laminating thin films. It should be pointed out that the relationship between the film stress can be used for explanation.

  When a thin film is formed on the ground, the moment generated in the base and the moment generated in the thin film are balanced. In this case, the force that generates the moment inside the thin film is the internal stress of the film, that is, the film stress.

  When the ground and the thin film are balanced, S = σ × d, where S is the total stress, σ is the internal stress, that is, the film stress, and d is the film thickness.

  The film stress may be an internal stress that tends to shrink the thin film, that is, a tensile stress, or an internal stress that tends to spread the thin film, that is, a compressive stress. Whether it is a tensile stress or a compressive stress, and the magnitude of the film stress can be adjusted by the material and the forming conditions for forming the thin film.

  The behavior when the internal stress of the thin film is a tensile stress and the compressive stress will be schematically described with reference to FIGS. 7 (a) and 7 (b).

  FIG. 7A shows the behavior when the film stress of the thin film 22 is a tensile stress when the thin film 22 is formed on the substrate 21 as a base. As shown in FIG. 7A, when the thin film 22 is formed on the substrate 21 and the moment generated in the substrate 21 and the moment generated in the thin film are balanced, the film stress of the thin film 22 is increased. Is a tensile stress, the thin film 22 is about to shrink as indicated by an arrow. As a result, the substrate 21 is warped so as to protrude downward.

  On the other hand, FIG. 7B shows the behavior when the thin film 23 is formed on the substrate 21 and the internal moments of both are balanced, the film stress in the thin film 23 is a compressive stress. Here, the thin film 23 acts in a direction in which the substrate 21 is expanded as indicated by an arrow. Therefore, the substrate 21 is warped so as to protrude toward the thin film 23 in the region where the thin film 23 is formed.

  That is, when a plurality of thin films are sequentially formed by the thin film formation method, a laminate composed of a plurality of thin films may be warped downward or convex upward depending on the relationship between the film stress and the film thickness of each thin film. I understand that Prior to the filing of the present application, when a thin film is formed by a thin film forming method, the thin film has a film stress as the internal stress, and the film stress is adjusted by adjusting the thin film forming material and the thin film forming conditions. It was known to get.

  The film stress σ is measured by measuring the bending of the substrate with a stylus-type film thickness meter when a circular thin film is formed on a circular substrate and based on the bending amount. It calculated | required by Formula (1).

σ = Et ² / {6 (1-ν) rd} (1)
In Equation (1), E is the Young's modulus of the substrate, ν is the Poisson's ratio of the substrate, t is the thickness of the substrate, d is the thickness of the thin film, and r is the radius of curvature of the substrate. Indicates. The radius of curvature r is a value corresponding to the amount of bending of the substrate after the thin film is formed. When the amount of bending of the substrate determined by the palpation film thickness meter is δ, it is determined by r = L ² / (8δ). It is done. L is the diameter of the circular substrate.

  The film stress value of each thin film in the present specification is a value obtained by the method of measuring the amount of bending of the substrate. In this case, the substrate is made of Si, has a thickness of 380 μm, and has a diameter of What was 30 mm was used. In this case, Young's modulus is 127 GPa and Poisson's ratio is 0.3. The amount of bending of the substrate when one thin film was formed on the substrate by sputtering so as to have the thickness in the above-described embodiment was measured, and the film was formed on the substrate based on the above formula (1). The film stress of the thin film was determined.

  According to the above method, as long as the Young's modulus and Poisson's ratio of the substrate are known, the film stress can be easily measured only by measuring the amount of bending of the substrate regardless of the crystallinity of the thin film.

  Note that the film stress varies depending on not only the material type of the thin film formed on the substrate but also, for example, sputtering, RF power, gas pressure and gas flow rate during sputtering, and substrate material. The value of the film stress can be adjusted by changing the RF power, gas pressure, gas flow rate, or the like.

  As a thin film forming method, vapor deposition or CVD may be used instead of sputtering.

  In the piezoelectric thin film vibration device 1 of the present embodiment, the thin film vibrator is configured by a laminated film in which the plurality of thin films described above are laminated, and each thin film has the above-described film stress and film thickness relationship. By providing the tensile films 10 and 11, as shown in a schematic perspective view in FIG. 2B, the corner portions indicated by the arrows C1 to C4 are warped so as to be positioned upward. In FIG. 2B, the thin-film vibrating body 2 having a rectangular planar shape has a first side 2 a and a second side 2 b that face each other. And the 1st support part 12 is connected with the center of the 1st edge | side 2a, and the support part 13 is connected with the center of the 2nd edge | side 2b. The support parts 12 and 13 are parts fixed to the support substrate 3. The thin film vibrator 2 is floated on the support substrate at intervals except for the portion fixed to the support substrate 3.

  The tensile films 10 and 11 have a stripe shape extending in parallel along the first and second sides 2a and 2b. The stripe regions where the tensile films 10 and 11 are formed are defined as first and second stripe regions. In the present embodiment, in the first and second striped regions, the relationship between the film stress and the film thickness of each thin film constituting the thin film vibrator 2 is connected to the first and second support portions. The warped part is warped so as to protrude downward. More specifically, due to the tensile stress of the tensile films 10 and 11, the thin film vibrator 2 is located at the center of the tensile films 10 and 11, that is, the center of the first and second sides 2 a and 2 b. The part where the two support parts 12 and 13 are connected will warp so as to protrude downward.

  Therefore, the corner portions indicated by arrows C1 to C4 in FIG. 2B are positioned above the first and second support portions 12 and 13. Therefore, the corner portions C <b> 1 to C <b> 4 are difficult to contact the support substrate 3.

In the present embodiment, the thin-film vibrating body 2 warps so that the center is convex upward in the direction connecting the first and second support portions 12 and 13 for the following reason. That is, in the thin-film vibrating body 2, when the excitation electrodes 5 and 7 are ignored, the temperature characteristic adjusting film 4, the piezoelectric thin film 6, the stress relaxation film 8, and the temperature characteristic adjusting film 9 made of SiO ₂ are laminated from below. Since the tensile films 10 and 11 are provided along the first and second sides 2a and 2b as described above, the first and second support portions 12 and 13 are connected. It will be omitted when considering the warpage in the direction.

The film thickness of the lower temperature characteristic adjusting film 4 is 1.7 μm, the film stress is −180 MPa, the film thickness of the piezoelectric thin film 6 is 1.6 μm, and the film stress is −80 MPa. On the other hand, the temperature characteristic adjusting film 9 occupying most of the upper part of the thin film vibrator 2 has a film thickness of 3.3 μm and a film stress of −180 MPa. The warp of the thin film vibrator 2 is determined by the relationship between the film stress and the film thickness of the plurality of thin films. Here, since the film stress of the temperature characteristic adjusting film made of SiO ₂ disposed above is −180 MPa, and the film thickness is 3.3 μm which is very thick as described above, the thin film vibrator 2 is configured. The relationship between the film stress and the film thickness of the plurality of thin films is such that the first and second support parts 12 and 13 are positioned at the lowest position in the direction connecting the first and second support parts 12 and 13. Will be warped.

  The stress relaxation film 8 is not provided for adjusting the warp in the direction connecting the first and second support parts 12 and 13, but has a structure in which the thin film vibrator 2 is supported by the support part. As will be apparent from the manufacturing method described later, the sacrificial layer is removed after the thin film vibrator is formed on the sacrificial layer. In this case, when the sacrificial layer is removed, stress is applied from the thin film vibrator 2 to the support portion. In order to reduce this stress, the stress relaxation film 8 is disposed.

  In the present embodiment, since the relationship between the film stress and the film thickness of each thin film constituting the thin film vibrator 2 is set as described above, as shown in FIG. In the direction connecting the first and second support portions 13 and 14 so that the first and second support portions 12 and 13 are positioned at the lowest position in the first and second sides 2a and 2b, It will warp so that the 1st, 2nd support parts 12 and 13 may be located in the lowermost part.

  Therefore, the central portion of the thin film vibrator 2 is also made difficult to contact the support substrate 3. Therefore, according to the present embodiment, since none of the corner portions C1 to C4 and the center portion are in contact with the support substrate 3, vibration characteristics and electrical characteristics are not easily deteriorated due to contact with the support substrate 3.

  In addition, even when heated during reflow soldering or under high temperature during actual use, distortion is caused by the difference in thermal expansion coefficient of each thin film portion constituting the thin film vibrator 2 However, the corner portions C <b> 1 to C <b> 4 and the central portion are unlikely to contact the support substrate 3. Therefore, the desired vibration characteristics and electrical characteristics can be obtained with certainty.

  Next, with reference to FIGS. 3 to 6, the manufacturing method of the piezoelectric thin film vibration device according to the first embodiment will be described to clarify the structure of the entire piezoelectric thin film vibration device.

  First, as shown in FIG. 3A, a support substrate 3 is prepared. In the present embodiment, a Si substrate is used as the support substrate 3. However, instead of the Si substrate, glass, dielectric ceramics, organic material, metal, or the like may be used. However, when the support substrate 3 is made of a conductive material such as metal, it is necessary to prevent a short circuit with an excitation electrode or the like to be described later.

  A sacrificial layer 14 made of ZnO is formed on the support substrate 3 by sputtering so as to have a thickness of 1.0 μm. 3B to 5B, the thin film vibrating body 2 is formed. At the same time, the first and second support portions 12 and 13 connected to the thin film vibrating body 2 are also described later. Will be formed.

Next, as shown in FIG. 3B, the temperature characteristic adjusting film 4 is formed so as to cover the sacrificial layer 14. That is, the temperature characteristic adjusting film 4 is formed by depositing SiO ₂ to a thickness of 1.7 μm by sputtering and patterning.

  Thereafter, as shown in FIG. 3C, Pt is deposited by vapor deposition so as to have a film thickness of 0.1 μm, and patterned by etching, lift-off, etc., thereby forming the first excitation electrode 5.

  Next, as shown in FIG. 3D, a film of AlN is formed by sputtering so as to have a thickness of 1.6 μm, and is patterned by etching and lift-off to form a piezoelectric thin film 6.

  Thereafter, as shown in FIG. 4A, the second excitation electrode 7 is formed by forming a film of Pt again by vapor deposition to a thickness of 0.1 μm and patterning.

  Next, as shown in FIG. 4B, AlN is deposited to a thickness of 0.8 μm, and the stress relaxation film 8 is formed.

Thereafter, as shown in FIG. 4C, a temperature characteristic adjusting film 9 is formed by sputtering and patterning SiO ₂ to a thickness of 3.3 μm.

  Finally, AlN is formed by sputtering so as to have a thickness of 0.8 μm, and is patterned to form the tensile films 10 and 11 shown in FIG.

  FIG. 5B is a schematic plan view showing the thin film laminate on the support substrate obtained as described above. 5A is a cross-sectional view taken along line BB in FIG. 5B.

  Thereafter, the sacrificial layer 14 is removed by wet etching using acetic acid to form a gap 15 as shown in FIG. In this way, the piezoelectric thin film vibration device 1 shown in FIG. 6 is obtained.

  In the above manufacturing method, after the sacrificial layer 14 made of ZnO is formed, each thin film constituting the thin film vibrator 2 is formed, and finally the sacrificial layer 14 is removed. In this case, the absolute value of the film stress of each thin film when the sacrificial layer 14 made of ZnO is present is different from the absolute value of the film stress of each thin film when the sacrificial layer 14 is not present.

  However, the relationship between the film stresses between the thin films is relative, and therefore the thin film vibrator 2 is configured even when the sacrificial layer 14 is present and after the sacrificial layer 14 is removed. The relative relationship between the film stresses of the plurality of thin films is maintained in the same manner. Therefore, the relationship between the film stresses between the thin films based on the film stress measured on the Si substrate is the same film stress relationship even in the thin film vibrator 2 from which the sacrificial layer 14 is removed.

  In FIG. 6, in the portion where the tensile films 10 and 11 are provided, that is, in the vicinity of the first side 2 a and the second side 2 b of the thin film vibrating body 2, a plurality of thin films are supported by the first and second supports. It inclines so that the part 12 and 13 side may be approached. However, actually, as shown in FIG. 1, in the portion where the thin-film vibrating body 2 is configured, the plurality of thin films are not inclined in the vicinity of the support portions 12 and 13, and are indicated by a one-dot chain line in FIG. Thus, the support parts 12 and 13 are inclined and connected to the side of the thin film laminated portion constituting the thin film vibrator 2. In FIG. 6, for the purpose of illustrating the manufacturing method using the sacrificial layer 14, the piezoelectric thin film 6 and the like are only shown to be inclined below the tensile films 10 and 11. Actually, as shown by a one-dot chain line in FIG. 1, the inclined support portion is connected to the side of the thin-film vibrating body.

  In the above manufacturing method, the sacrificial layer 14 is formed of ZnO. However, in addition to ZnO, the sacrificial layer can be formed of an appropriate material that can be removed by application of a solvent or energy. Examples of the material for forming the sacrificial layer 14 include Al, Cu, and organic materials.

  As the solvent used when removing the sacrificial layer 14 by wet etching, acetic acid, nitric acid, or the like can be used when the sacrificial layer is ZnO, and an appropriate solvent is used depending on the material constituting the sacrificial layer. Can be used.

  In the piezoelectric thin film vibration device 1 according to the present embodiment, as described above, the thin film vibration body 2 has the corner portions C1 to C4 and the central portion positioned above the first and second support portions 12 and 13. Since it is warped, it is difficult for the thin-film vibrating body 2 to come into contact with the support substrate 3, so that desired vibration characteristics and electrical characteristics can be obtained with certainty.

In addition, the piezoelectric thin film 6 is made of AlN and has a negative frequency temperature coefficient TCF. In contrast, the temperature characteristic adjusting films 4 and 9 made of SiO ₂ have a positive frequency temperature coefficient TCF. Therefore, the combination of the piezoelectric thin film made of AlN and the temperature characteristic adjusting films 4 and 9 made of SiO ₂ makes it possible to reduce changes in characteristics due to temperature changes.

  In the present embodiment, the temperature characteristic adjustment film 9 is disposed above the piezoelectric thin film 6, and the temperature characteristic adjustment film 4 is disposed below the piezoelectric thin film 6. However, in the present invention, the temperature characteristic adjusting film may be disposed only at one of the upper position and the lower position of the piezoelectric thin film.

  FIG. 8 is a cross-sectional view schematically showing a part of a thin film vibrating body that is a main part of a piezoelectric thin film vibration device according to a second embodiment of the present invention, and corresponds to FIG. 1 showing the first embodiment. FIG.

  In the thin film vibrating body 41 of the piezoelectric thin film vibration device of the second embodiment, the temperature characteristic adjustment film 42, the first excitation electrode 43, the piezoelectric thin film 44, the second excitation electrode 45, the temperature characteristic adjustment film 46, in order from the bottom. A stress adjusting film 47, a temperature characteristic adjusting film 48, and tensile films 49 and 50 are laminated. The material, thickness, and film stress of each film are as follows.

  Tensile films 49, 50: AlN, film thickness 0.8 μm, film stress is tensile stress, value is 100 MPa.

Temperature characteristic adjusting film 48: SiO ₂ , film thickness 3.0 μm, film stress is compressive stress, value is −180 MPa.

  Stress adjustment film 47: AlN, film 0.8 μm, film stress is tensile stress, value is 100 MPa.

Temperature characteristic adjusting film 46: SiO ₂ , film thickness 2.0 μm, film stress is compressive stress, value is −180 MPa.

  Second excitation electrode 45: Pt, film thickness 0.1 μm.

  Piezoelectric thin film 44: AlN, film thickness 1.6 μm, film stress is compressive stress, value is −80 MPa.

  First excitation electrode 43: Pt, film thickness 0.1 μm.

Temperature characteristic adjusting film 42: SiO ₂ , film thickness 0.1 μm, film stress is compressive stress, value is −180 MPa.

  As described above, the laminated form of the thin film vibrator is not limited to that of the first embodiment, and the temperature characteristic and the warp of the thin film laminated body can be reduced by appropriately laminating the temperature characteristic adjusting film and the stress adjusting film. It is possible to adjust. In the second embodiment, similarly to the first embodiment, the tensile films 49 and 50 are provided in the first and second stripe regions described above along the first and second sides. In the second side, the thin-film vibrating body is warped so as to protrude downward so that the portion where the first and second support portions are connected is located at the lowest position.

  Also in this embodiment, since the thin films including the stress adjusting film 47 are laminated as described above, the internal stress due to the film stress and film thickness relationship of the plurality of thin films is laminated in the thickness direction. When the upper portion and the lower portion are distinguished from each other, the internal stress due to the relationship between the film stress and the film thickness of the plurality of thin films is relatively smaller in the lower portion than in the upper portion. Therefore, in the direction connecting the first and second support portions, the center is positioned upward and the first and second support portions are set to warp so as to be positioned lowest.

  Therefore, also in this embodiment, not only can the thin film vibrator be securely fixed to and supported by the first and second support portions on the support substrate, but also undesired contact of the thin film vibrator with the support substrate can be ensured. Can be prevented.

In the second embodiment, the temperature characteristic adjusting films 42, 46, and 48 are laminated. That is, the temperature characteristic adjusting films 42, 46, 48 are all made of SiO ₂ and have a positive frequency temperature coefficient TCF. Accordingly, the frequency temperature coefficient TCF of the temperature characteristic adjusting films 42, 46, and 48 and the frequency temperature coefficient TCF of the piezoelectric thin film 44 made of AlN are offset. Therefore, the absolute value of the frequency temperature coefficient TCF can be reduced.

  Also in this embodiment, since the temperature characteristic adjusting film is disposed, it is possible to provide a piezoelectric thin film vibration device with little characteristic change due to temperature change.

  FIG. 9 is a cross-sectional view schematically showing a thin film vibrating body of a piezoelectric thin film vibrating apparatus according to a third embodiment of the present invention.

  In the third embodiment, the thin-film vibrating body 51 has a structure in which a first excitation electrode 52, a piezoelectric thin film 53, a second excitation electrode 54, a temperature characteristic adjustment film 55, and tensile films 56 and 57 are stacked from below. . The material, film thickness, and film stress of each thin film are as follows.

  Tensile films 56 and 57: AlN, film thickness 0.8 μm, film stress is tensile stress, value is 100 MPa.

Temperature characteristic adjusting film 55: SiO ₂ , film thickness 5.0 μm, film stress is compressive stress, value is −180 MPa.

  Second excitation electrode 54: Pt, film thickness 0.1 μm.

  Piezoelectric thin film 53: AlN, film thickness 1.6 μm, film stress is compressive stress, value is −80 MPa.

  First excitation electrode 52: Pt, film thickness 0.1 μm.

  In the third embodiment, a single layer of the temperature characteristic adjusting film 55 and the tension films 56 and 57 are formed on the laminate in which the piezoelectric thin film 53 and the first and second excitation electrodes 52 and 54 are laminated. Are stacked. Also in this case, since the tensile films 56 and 57 are provided in the first and second stripe regions along the first and second sides, the first film is formed in the same manner as in the first embodiment. The thin-film vibrating body 53 is provided with the first and second support portions on the first and second sides so that the second support portion is positioned at the lowest position on the first and second sides. It will warp so as to be convex downward so that the portion is the lowest.

  Also in the present embodiment, between the first and second stripe regions, the relationship between the film stress and film thickness of the plurality of thin films is set to warp upward in the direction connecting the first and second support portions. ing. Therefore, also in the present embodiment, the center of the direction in which the thin film vibrating body connects the first and second support portions is warped upward.

  Therefore, also in this embodiment, the corner portion of the thin-film vibrating body 51 is difficult to contact the support substrate. In addition, due to the presence of the temperature characteristic adjusting film 55, a change in characteristics due to a temperature change can be reduced.

  FIG. 10 is a cross-sectional view schematically showing a thin film vibrating body of the piezoelectric thin film vibrating apparatus according to the fourth embodiment. In the fourth embodiment, the thin film vibrator 61 has the same number of thin film stacks as the third embodiment. However, the material, film thickness, and film stress of each thin film are as follows.

  Tensile films 66 and 67: Pt, film thickness of 0.8 μm, thin film formed by vapor deposition, the film stress is tensile stress, and the value is 100 MPa.

Temperature characteristic adjustment film 65: SiO ₂ , film thickness 5.0 μm, film stress is compressive stress, value is −180 MPa.

  First and second excitation electrodes 62 and 64: each made of Pt and having a film thickness of 0.1 μm.

  Piezoelectric thin film 63: made of ZnO, film thickness 1.0 μm, film stress is compressive stress, value is −50 MPa.

Also in the fourth embodiment, the remaining thin films are formed by sputtering except that the first and second excitation electrodes 62 and 64 and the tensile films 66 and 67 made of Pt are formed by vapor deposition. Yes. Also in this embodiment, the film stress of the tensile films 66 and 67 and the temperature characteristic adjustment film 65 made of SiO ₂ and the film stress of the piezoelectric thin film 64 are set to the above values. Similarly to the case, in the direction connecting the first and second support parts so that the first and second support parts are positioned at the lowest position on the first and second sides, the first and second support parts are provided. The piezoelectric thin-film vibrating body 61 warps so that the two support portions are at the bottom, that is, the center is at the top. Therefore, contact of the corner portion with the support substrate can be reliably prevented.

  As apparent from the first to fourth embodiments, in the present invention, the number of thin films constituting the thin film vibrator, the material of the thin film, the film thickness, and the film stress may be adjusted as appropriate. Thereby, the thin film vibrator can be warped as shown in FIG. 2B, and the contact of the corner portions C1 to C4 with the support substrate can be surely and easily prevented.

  FIGS. 11A and 11B are a schematic cross-sectional view of a thin film vibrating body of a piezoelectric thin film vibration device according to a fifth embodiment of the present invention and a schematic plan view of the piezoelectric thin film vibration device.

  In the fifth embodiment, the thin film vibrating body 71 includes a first excitation electrode 72, a piezoelectric thin film 73, a second excitation electrode 74, a tensile film 75, and a stress adjustment film 76 that also serves as a temperature characteristic adjustment film stacked from below. It has a structure. Here, the first excitation electrode 72, the piezoelectric thin film 73, the second excitation electrode 74, and the tensile film 75 are formed so as to reach the entire rectangular region of the rectangular thin film vibrating body 71. The planar shape of the thin-film vibrating body 71 is a rectangular shape, and the first and second sides 71a and 71b are a pair of sides extending in the short side direction. On the other hand, the stress adjustment film 76 also serving as the temperature characteristic adjustment film is formed only in the central region with the first and second sides 71a and 71b and the first and second stripe regions G and G separated from each other. ing. However, the stress adjusting film 76 is formed so as to reach the entire width in the width direction of the rectangular thin film vibrator 71, that is, the short side direction.

  In other words, the tensile film is not formed in the first and second stripe regions where the tensile film provided in the first to fourth embodiments is provided, and the tensile film is formed. A stress adjusting film 76 having a compressive stress is provided in the central region between the first and second stripe-shaped regions.

  Accordingly, the stress adjusting film 76 does not exist above the tensile film 75 in the stripe-shaped regions along the first and second sides 71a and 71b.

  The material, film thickness, and film stress of each thin film are as follows.

Stress adjustment film 76: SiO ₂ , film thickness 5.0 μm, film stress is compressive stress, value is −180 MPa.

  Tensile film 75: AlN, film thickness 0.8 μm, film stress is tensile stress, value is 100 MPa.

  Second excitation electrode 74: Pt, film thickness 0.1 μm.

  Piezoelectric thin film 73: AlN, film thickness 1.6 μm, film stress is compressive stress, value is −80 MPa.

  First excitation electrode 72: Pt, film thickness 0.1 μm.

  Also in this embodiment, the film stress of the first and second excitation electrodes made of Pt having a film thickness of 0.1 μm can be ignored because the film stress is small.

  In this embodiment, the piezoelectric thin film 73, the tensile film 74, and the stress adjustment film 76 having the above-described film stress are laminated, and the first and second sides 71a and 71b are formed on the tensile film 74 formed on the entire surface. The stress adjusting film 76 does not exist on the striped regions G and G along

Therefore, in the present embodiment, the behavior of the tensile film 74 made of AlN differs between the central portion where the large thickness stress adjusting film 76 made of SiO ₂ is present and the first and second stripe-shaped regions that are not present. It becomes.

  More specifically, in the central region, the sum of the film stresses in the upper part when the thin film vibrator is divided into two in the thickness direction is compressive stress. That is, the relationship between the film stress and the film thickness of the plurality of thin films constituting the thin film vibrating body is the center in the direction connecting the first and second support portions, as in the first and second embodiments described above. Is set to be convex upward. Therefore, the center of the thin-film vibrating body warps upward in the direction connecting the first and second support portions.

  On the other hand, in the first and second stripe regions, the first and second sides 71 a and 71 a of the thin film vibrating body 71 are caused by the relationship between the film stress and the film thickness in the laminate including the tensile film 74 and the piezoelectric thin film 73. The center of 71b will warp convex downward.

  Therefore, also in the present embodiment, the contact of the corner portion and the center portion of the thin-film vibrating body 71 with the support substrate 3 can be reliably prevented.

  Further, in the present embodiment, due to the presence of the stress adjustment film 76 that also serves as the temperature characteristic adjustment film, a change in characteristics due to a temperature change can be reduced.

  In the thin film vibrator 2 shown in FIG. 1, the positions of the thin films are aligned on the side surface of the thin film vibrator. However, in the present invention, for example, as in the fourth embodiment, the thin film vibrator In this aspect, the positions of the thin films do not have to be aligned. FIG. 12A shows another modification in which the position of the thin film is not aligned on the side surface of such a thin film vibrating body. The modification shown in FIG. 12A is the same as the thin film vibrator 2 of the first embodiment except that the position of the thin film is not aligned on the side surface of the thin film vibrator 2.

  In the modification shown in FIG. 12A, the piezoelectric thin film 6 is laminated on the first excitation electrode 5, and the second excitation electrode 7 has an outer edge that is more than that of the first excitation electrode. Was also formed to be located inside. Thus, in this invention, the 1st, 2nd excitation electrodes 5 and 7 may exist in the position where the outer edge is different.

  As shown in FIG. 12B, the first excitation electrode 5 may be provided such that the outer edge is positioned on the inner side than the second excitation electrode 7. On the other hand, as shown in FIG. 12C, the piezoelectric thin film is thinner than the outer edge of the second excitation electrode 7 formed on the lower surface of the piezoelectric thin film 6 than the outer edge of the second excitation electrode 7. The outer edge of the first excitation electrode 5 formed on the lower surface of 6 may reach the outside.

  However, the modification shown in FIG. 12C is preferable to the modification shown in FIG. This is because when the thin film vibrator is formed, the first excitation electrode 5 is formed, and then the piezoelectric thin film 6 is laminated to form the second excitation electrode 7. In FIG. 12B, a step indicated by an arrow Q is generated in the piezoelectric thin film 6 due to the thickness of the first excitation electrode 5. At this level difference Q, a voltage is applied between the upper second excitation electrode 7 and the first excitation electrode 5, and at the level difference Q, a crack occurs in the piezoelectric thin film 6 or the piezoelectric The characteristics sometimes changed.

  On the other hand, in the structure shown in FIG. 12C, when the piezoelectric thin film 6 is formed after the first excitation electrode 5 is formed, a step Q is produced, but the outer edge of the second excitation electrode 7 is formed. However, even if a voltage is applied between the first and second excitation electrodes 5 and 7, the voltage is applied at the level difference Q because the first excitation electrode 5 is positioned inside the outer edge. hard. Therefore, cracks are unlikely to occur at the step Q, and deterioration of the piezoelectric characteristics is difficult to occur.

  Therefore, also in the method for manufacturing the piezoelectric thin film vibration device of the present invention, preferably, after the first excitation electrode 5 and the piezoelectric thin film 6 are formed, the outer edge of the second excitation electrode 7 is the first excitation electrode 5. It is desirable to form the second excitation electrode 7 so as to be positioned inside the outer edge of the second excitation electrode 7.

  FIG. 13 is a schematic front sectional view showing an example of a package structure when the piezoelectric thin film vibration device of the present invention is commercialized. In the package structure 81, a case substrate 82 made of Si, glass, dielectric ceramics, organic material, metal, or the like is bonded onto the piezoelectric thin film vibration device 1 using bumps 83a to 83d. In this case, it is necessary to provide a sufficient gap between the lower surface of the case substrate 82 and the upper surface of the thin film vibrator 2 of the piezoelectric thin film vibration device 1. Otherwise, the thin film vibrator 2 comes into contact with the lower surface of the case substrate 82.

  On the other hand, in the thin film vibrating body 2 of the first embodiment, as described above, the corner portions C1 to C4 are located above the portion connected to the support portion. Therefore, in order to reliably prevent contact between the corner portions C1 to C4 and the lower surface of the case substrate 82, it is desirable to round the corner portions C1 to C4.

  In each of the embodiments and modifications described above, AlN is used as the piezoelectric thin film. However, the present invention is not limited to AlN, and piezoelectric thin films made of various other piezoelectric materials can be used.

  Further, the electrode material is not limited to Pt, and an appropriate metal material such as Au, Cu, or an alloy thereof can be used.

Further, the temperature characteristic adjusting film is not limited to SiO ₂ , and a thin film made of an appropriate material having a polarity and size different from the frequency temperature coefficient TCF of the piezoelectric thin film can be used.

  Further, the material constituting the tensile film is not limited to AlN, and an appropriate inorganic material or organic material such as Cu or Au can be used.

Similarly, for the stress relaxation film, an appropriate inorganic material or organic material such as SiO ₂ or Ta ₂ O ₅ can be used in addition to AlN.

  Furthermore, in the first to fifth embodiments described above, each thin film is mainly formed by sputtering, but may be formed by an appropriate vapor deposition method such as PVD or CVD, or ion plating. Then, the film stress may be appropriately adjusted by changing the film forming conditions for the thin film, as in the above embodiment.

It is sectional drawing which shows typically the thin film vibrating body of the piezoelectric thin film vibration apparatus of the 1st Embodiment of this invention, and sectional drawing which follows the AA line in Fig.2 (a). (A) is a schematic plan view of the piezoelectric thin-film vibrating device in the first embodiment, and (b) is a schematic perspective view showing a state in which the thin-film vibrating body is warped. (A)-(d) is each typical front sectional drawing for demonstrating the manufacturing method of the piezoelectric thin film vibration apparatus of 1st Embodiment. (A)-(c) is each typical front sectional drawing for demonstrating the manufacturing process of the piezoelectric thin film vibration apparatus of the 1st Embodiment of this invention. (A) is front sectional drawing for demonstrating the manufacturing process of the piezoelectric thin film vibration apparatus of 1st Embodiment, (b) is the typical top view. 1 is a front sectional view of a piezoelectric thin film vibration device according to a first embodiment. (A) is a schematic front view showing a state of warping when a thin film is formed on a substrate and the film stress of the thin film is a tensile stress, and (b) is a case where the film stress of the thin film is a compressive stress. The typical front view which shows the state of curvature. Front sectional drawing which shows typically the thin film vibration body of the piezoelectric thin film vibration apparatus which concerns on the 2nd Embodiment of this invention. Front sectional drawing which shows typically the thin film vibrating body of the piezoelectric thin film vibration apparatus which concerns on the 3rd Embodiment of this invention. FIG. 10 is a front sectional view schematically showing a thin film vibrating body of a piezoelectric thin film vibrating apparatus according to a fourth embodiment of the present invention. (A) And (b) is front sectional drawing which shows typically the thin film vibration body of the piezoelectric thin film vibration apparatus which concerns on the 5th Embodiment of this invention, and a typical top view of this piezoelectric thin film vibration apparatus. (A) is typical sectional drawing which shows the modification of the thin film vibrating body of the piezoelectric thin film vibration apparatus in 1st Embodiment, (b) and (c) are the vibrations of the piezoelectric thin film vibration apparatus in 1st Embodiment. Each partial notch front sectional drawing for demonstrating the further another modification of a body. The typical front sectional view showing the package structure containing the piezoelectric thin film oscillating device of a 1st embodiment. The perspective view which shows the conventional piezoelectric thin film vibration apparatus. The typical front sectional view showing an example of the conventional piezoelectric thin film resonator. The schematic perspective view for showing the problem of an example of the conventional piezoelectric thin film resonator.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Piezoelectric thin film vibration device 2 ... Thin film vibrating body 2a, 2b ... 1st, 2nd edge 3 ... Supporting substrate 4 ... Temperature characteristic adjustment film 5 ... 1st excitation electrode 6 ... Piezoelectric thin film 7 ... 2nd excitation electrode DESCRIPTION OF SYMBOLS 8 ... Stress relaxation film | membrane 9 ... Temperature characteristic adjustment film | membrane 10, 11 ... Tensile film | membrane 12, 13 ... 1st, 2nd support part 14 ... Sacrificial layer 21 ... Substrate 22 ... Thin film 23 ... Thin film 41 ... Thin film vibrating body 42 ... Temperature Characteristic adjusting film 43 ... first excitation electrode 44 ... piezoelectric thin film 45 ... second excitation electrode 46 ... temperature characteristic adjusting film 47 ... stress adjusting film 48 ... temperature characteristic adjusting film 49, 50 ... tensile film 51 ... thin film vibrating body 52 ... 1st excitation electrode 53 ... Piezoelectric thin film 54 ... 2nd excitation electrode 55 ... Temperature characteristic adjustment film 56, 57 ... Pulling film 61 ... Thin film vibrating body 62 ... 1st excitation electrode 63 ... Piezoelectric thin film 64 ... 2nd Excitation electrode 65 ... Temperature characteristic adjustment film 66, 6 ... tensile film 71 ... thin film vibrator 72 ... first excitation electrode 73 ... piezoelectric thin film 74 ... second excitation electrode 75 ... tension film 76 ... stress adjustment film 81 ... package structure 82 ... case substrates 83a to 83d ... bumps G, G: Striped area

Claims (8)

A support substrate;
On the support substrate, it is arranged to be floated from the upper surface of the support substrate, and is composed of a laminated film formed by laminating a plurality of thin films formed by a thin film forming method, and a thin film vibrator having a rectangular planar shape;
A first support portion and a second support portion that are connected to a part of the opposing first and second sides of the rectangular shape of the thin-film vibrating body and are fixed to the support substrate;
The thin film vibrator includes a piezoelectric thin film, a first excitation electrode laminated on the lower surface of the piezoelectric thin film, a second excitation electrode laminated on the upper surface of the piezoelectric thin film, and the first and second sides. The first and second striped tensile films arranged so as to extend and the thin film vibrating body as a thin film of the plurality of thin films, the first extending along the first and second sides. , And at least a stress adjusting film whose film stress is compressive stress in a central region between the second stripe-shaped regions ,
As the thin film vibrating body warps upward in the direction connecting the first and second sides, and as it goes outward from the first and second support portions on the first and second sides. The relationship between the film stress and the film thickness of the plurality of thin films constituting the thin film vibrator is set so that the film is positioned upward and warped downward on the first and second sides. By
In the first and second sides, the first and second support portions are located at the lowest position, and the first and second support portions are the most in the direction connecting the first and second support portions. A piezoelectric thin-film vibration device in which the thin-film vibration body is warped so as to be positioned below. 2. The piezoelectric thin film vibration device according to claim 1, wherein the plurality of thin films include a temperature characteristic adjustment film made of a material having a frequency temperature coefficient opposite in polarity to the frequency temperature coefficient of the piezoelectric thin film. 2. The piezoelectric thin film vibration device according to claim 1 , wherein the stress adjustment film is also a temperature characteristic adjustment film made of a material having a frequency temperature coefficient opposite to the frequency temperature coefficient of the piezoelectric thin film . Of the first and second excitation electrodes laminated via the piezoelectric thin film, the first excitation electrode laminated on the lower surface of the piezoelectric thin film reaches the outside of the second excitation electrode. The piezoelectric thin film vibration device according to any one of claims 1 to 3 . Preparing a support substrate;
Forming a sacrificial layer made of a material that can be eliminated by applying a solvent or energy on the support substrate; and
A rectangular thin-film vibrator is connected to a part of the opposing first and second sides of the rectangular shape so as to cover the sacrificial layer, and is fixed to the support substrate. Forming with the second support,
Disposing the sacrificial layer by a solvent or by applying energy, thereby providing a gap between the thin film vibrator and the support substrate,
In forming the thin film vibrator, the piezoelectric thin film, the first excitation electrode laminated on the lower surface of the piezoelectric thin film, the second excitation electrode laminated on the upper surface of the piezoelectric thin film, and the first and second electrodes The striped first and second tensile films arranged so as to extend along the side, and the thin film vibrating body as one thin film of the plurality of thin films, along the first and second sides A plurality of thin films including at least a stress adjusting film whose film stress is a compressive stress is sequentially formed in a central region between the extending first and second stripe-shaped regions by a thin film forming method . In the direction connecting the sides of the first and second sides, the center of the first and second sides is convex upward, and the first and second support parts are located upward as they go outward. A plurality of the thin-film vibrators configured to warp downward on the second side Relation thin film stress and film thickness are set, whereby, said first, first being chosen second supporting portion, wherein the second side first, the second support portion Forming the thin film vibrator so as to warp the thin film vibrator so that the first and second support portions are located at the lowest position in the direction connecting the first and second support portions. A method of manufacturing a piezoelectric thin film vibration device, which is characterized. In forming the thin film vibrator, a temperature characteristic adjusting film made of a material having a frequency temperature coefficient opposite in polarity to the frequency temperature coefficient of the piezoelectric thin film is formed as at least one of the plurality of thin films. Item 6. A method for manufacturing a piezoelectric thin film vibration device according to Item 5 . 6. The method of manufacturing a piezoelectric thin film vibration device according to claim 5 , wherein the stress adjusting film is also a temperature characteristic adjusting film made of a material having a frequency temperature coefficient opposite in polarity to the frequency temperature coefficient of the piezoelectric thin film. In forming the thin film vibrator, the first excitation electrode and the piezoelectric thin film are formed, and then the second excitation electrode opposed to the first excitation electrode through the piezoelectric thin film is formed as the first excitation electrode. The method for manufacturing a piezoelectric thin film vibration device according to any one of claims 5 to 7 , wherein the piezoelectric thin film vibration device is formed so as not to reach outside of the excitation electrode.

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