JP4580766B2 - Thin film piezoelectric resonator and manufacturing method of thin film piezoelectric resonator - Google Patents

Description

  The present invention relates to a thin film piezoelectric resonator, and more particularly to a thin film piezoelectric resonator used in a high frequency band and a manufacturing method thereof.

  In recent years, wireless communication systems such as mobile communication devices such as mobile phones and wireless local area network (LAN) systems that transfer data between computers at high speed use a high frequency band of GHz or higher. A thin film piezoelectric resonator (FBAR) is a high-frequency element used in such a high frequency band electronic device such as a wireless communication system.

  Until now, bulk (ceramic) dielectric resonators and surface acoustic wave (SAW) elements have been used as resonators in the high frequency region. Compared to these resonators, the FBAR is suitable for downsizing and can cope with higher frequencies. For this reason, development of a high frequency filter, a resonance circuit, etc. using FBAR is underway.

  In the basic configuration of the FBAR, a piezoelectric film such as aluminum nitride (AlN) or zinc oxide (ZnO) is sandwiched between opposing lower and upper electrodes. For high performance, the resonant part of the FBAR is placed above the cavity. For example, in a stacked cavity type FBAR, a sacrificial layer deposited on a support substrate is processed, a lower electrode, a piezoelectric film, and an upper electrode are sequentially formed so as to cover the sacrificial layer, and then the sacrificial layer is removed to resonate the FBAR. A cavity is formed in the lower part of the part (see, for example, Patent Document 1). In addition, a lower electrode, an AlN layer, and an upper electrode are stacked on an insulating layer formed on the surface of a silicon (Si) substrate, and a cavity is formed below the lower electrode through a via penetrating the AlN layer, thereby producing an FBAR. There are some (see, for example, Patent Document 2).

The lower and upper electrodes are required to have less elastic loss due to piezoelectric resonance vibration in order to improve the resonance characteristics of the FBAR. Also, a function for adjusting the resonance frequency is required. Further, a low resistance metal is desired in order to suppress loss of electrical signals applied to the lower and upper electrodes. Furthermore, the lower electrode is required to have a function as a seed layer for forming a piezoelectric film with good orientation. As the single metal, molybdenum (Mo), tungsten (W), etc., which have a high melting point and a relatively low resistivity, are considered good. In particular, Mo, which is easy to take c-axis orientation, is often used for piezoelectric materials such as AlN. However, when the resonance frequency is increased, it is necessary to reduce the electrode film thickness as well as the piezoelectric film thickness. In this case, since the electrode resistance increases and the high frequency characteristics deteriorate, it is necessary to use a material having a lower resistance.
US Pat. No. 6,060,818 US Pat. No. 6,355,498

  The present invention provides an FBAR and an FBAR manufacturing method that can improve resonance characteristics and suppress deterioration of high-frequency characteristics.

  In order to solve the above-described problems, the first aspect of the present invention includes: (a) a first metal film on a substrate; (b) an amorphous metal film on the first metal film; A second metal film oriented in a direction perpendicular to the surface of the amorphous metal film on the crystalline metal film; and (d) a direction perpendicular to the surface of the second metal film on the second metal film. The gist of the present invention is a thin film piezoelectric resonator including a piezoelectric film oriented in the direction.

  In the second aspect of the present invention, (a) a first metal film is formed on a substrate, (b) an amorphous metal film is formed on the first metal film, and (c) an amorphous metal. A second metal film oriented in a direction perpendicular to the surface of the amorphous metal film is formed on the film, and (d) oriented in a direction perpendicular to the surface of the second metal film on the second metal film. The gist of the present invention is a method of manufacturing a thin film piezoelectric resonator including forming a piezoelectric film and (e) selectively removing the piezoelectric film using the amorphous metal film as an etching stop layer.

  ADVANTAGE OF THE INVENTION According to this invention, it becomes possible to provide the manufacturing method of FBAR and FBAR which can improve a resonance characteristic and can suppress degradation of a high frequency characteristic.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following description of the drawings, the same or similar parts are denoted by the same or similar reference numerals. However, it should be noted that the drawings are schematic, and the relationship between the thickness and the planar dimensions, the ratio of the thickness of each layer, and the like are different from the actual ones. Therefore, specific thicknesses and dimensions should be determined in consideration of the following description. Moreover, it is a matter of course that portions having different dimensional relationships and ratios are included between the drawings.

(First embodiment)
As shown in FIG. 1, the FBAR according to the first embodiment of the present invention includes a lower electrode 14 provided on the surface of the insulating film 32, a piezoelectric film 15 provided on the surface of the lower electrode 14, And an upper electrode 16 provided on the surface of the piezoelectric film 15. The resonance part 20 is defined by the area where the lower and upper electrodes 14 and 16 are opposed to each other on the cavity 17 and the piezoelectric film 15 sandwiched between the opposed lower and upper electrodes 14 and 16.

As shown in FIG. 2, the lower electrode 14, the piezoelectric film 15, and the upper electrode 16 are supported by a substrate 11 having a cavity 17 and an insulating film 32. The resonating unit 20 is disposed on the cavity 17. The lower electrode 14 includes a first metal film 21 provided on the insulating film 32 on the surface of the substrate 11, an amorphous metal film 22 provided on the surface of the first metal film 21, and an amorphous metal film 22. A second metal film 23 is provided on the surface and oriented in a direction perpendicular to the surface of the amorphous metal film 22. The second metal film 23 is provided only on the portion covered with the piezoelectric film 15. The end of the lower electrode 14 covered with the piezoelectric film 15 is inclined at an angle smaller than a right angle with respect to the surface of the insulating film 32. The substrate 11 is a semiconductor substrate such as Si. The insulating film 32 is a SiO ₂ film or the like.

  In the piezoelectric film 15 of the resonance unit 20, a high frequency signal is transmitted by resonance of the bulk acoustic wave excited by the high frequency signal applied to the lower electrode 14 or the upper electrode 16. For example, a high frequency signal in the GHz band applied from the lower electrode 14 is transmitted to the upper electrode 16 via the piezoelectric film 15 of the resonance unit 20. In order to obtain good resonance characteristics of the resonance unit 20, an AlN film or a ZnO film excellent in film quality including crystal orientation and the uniformity of film thickness is used as the piezoelectric film 15.

  The performance of the piezoelectric film 15 can be expressed by an electromechanical coupling coefficient that is an index of the magnitude of the piezoelectric effect, a quality factor Qm that is an index of the sharpness of mechanical vibration at the resonance frequency, and the like. In order to increase the electromechanical coupling coefficient of the piezoelectric film 15, it is important to align the polarization axis of the piezoelectric crystal in the thickness direction of the piezoelectric film 15. Moreover, a large quality factor Qm can be obtained by using a high-purity piezoelectric crystal and aligning the crystal orientation of the piezoelectric film with the polarization direction.

  The first metal film 21 and the upper electrode 16 of the lower electrode 14 are low-resistance metal films and suppress the deterioration of the high-frequency characteristics of the FBAR. For example, when the resonance frequency of the FBAR and the metal material used for the lower and upper electrodes 14 and 16 are determined, the thicknesses of the lower, upper electrodes 14 and 16 and the piezoelectric film 15 that maximize the electromechanical coupling coefficient are approximately It is determined uniquely. In addition, the maximum value of the electromechanical coupling coefficient at this time greatly depends on the elastic coefficient of the metal material used for the electrode, and if the density of the metal material is small, the optimum electrode thickness tends to increase. . Therefore, in order to reduce the resistance of the lower and upper electrodes 14 and 16, it is desirable to use a metal material having a low resistivity and a low density.

The resistivity at room temperature of the metal film used for the first metal film 21 and the upper electrode 16 is in the range of about 10 × 10 ⁻⁸ Ωm or less, preferably in the range of about 5 × 10 ⁻⁸ Ωm or less, more preferably about The range is 3 × 10 ⁻⁸ Ωm or less. As the first metal film 21 and the upper electrode 16, for example, aluminum (Al), copper (Cu), gold (Au), silver (Ag), iridium (Ir), molybdenum (Mo), nickel (Ni), platinum ( A low resistance metal such as Pt) or tungsten (W) is used. Further, an alloy containing a low resistance metal such as Al, Cu, Au, and Ag as a main component and adding Ni, Pt, Mo, W, or the like to about 10 wt% or less, desirably about 5 wt% or less may be used. By adding these, it can be expected to ensure flatness by suppressing hillocks in the thermal process and to improve the quality factor Qm resulting from an increase in electrode hardness. Further, Si and carbon (C) or the like may be added to the alloy at about 5 wt% or less. The upper electrode 16 can include a load electrode such as a TiW film for adjusting the resonance frequency of the resonance unit 20.

The amorphous metal film 22 and the second metal film 23 of the lower electrode 14 control the orientation of the piezoelectric film 15 deposited on the surface of the second metal film 23. For the amorphous metal film 22, an alloy such as aluminum tantalum (Al _x Ta _1-x ), titanium diboride (TiB ₂ ), or the like is used. With regard to Al _x Ta _1-x , for example, when the film is formed near the room temperature by sputtering or the like, the X-ray diffraction (XRD) ) And backscattered electron diffraction (RHEED). For the second metal film 23, a metal having a crystal habit such as Al, Au, Mo, and W is used. Al and Au are face-centered cubic lattice (fcc) metals and are easily oriented in the (111) orientation that is the crystal habit plane. Mo and W are body-centered cubic lattice (bcc) metals, and are easily oriented in the (110) orientation that is the crystal habit plane.

  For example, in a general polycrystalline metal layer, crystal grain surfaces having various crystal orientations appear. The surface of the polycrystalline metal layer is inferior in flatness due to unevenness depending on crystal grains. On the other hand, the surface of an amorphous layer such as a metal or an insulating film is uniform and flat. For example, the mean square roughness detected by a surface roughness meter or an atomic force microscope (AFM) is 3 nm or more on a polycrystalline metal surface, but 3 nm or less on an amorphous metal surface. . Therefore, the fcc metal and the bcc metal are easily formed on the surface of the amorphous layer while being oriented in the respective crystal habit planes.

Further, in comparison with an amorphous insulating film such as SiO ₂ ordinarily used as an underlayer or sacrificial layer on the substrate surface, an amorphous metal film generally has a larger surface energy. Accordingly, since the crystal growing on the amorphous metal film has a property of growing in layers to reduce the surface energy, the orientation can be further improved on the surface of the amorphous metal layer. For example, when Al is used as the second metal film 23, the second metal film 23 formed on the surface of the amorphous metal film 22 is a highly oriented film with a (111) orientation.

  In addition, a piezoelectric crystal such as AlN or ZnO used as the piezoelectric film 15 belongs to the hexagonal system. Hexagonal crystals originally have the property of being easily oriented in the (0001) orientation. Inheriting the high orientation of the second metal film 23, a piezoelectric crystal such as AlN or ZnO is formed by being highly oriented in the (0001) azimuth, that is, in the c-axis direction in a direction perpendicular to the surface of the second metal film 23. be able to. Here, the second metal film 23 and the piezoelectric film 15 may be formed as a highly oriented film with a half-value width of a rocking curve measured by XRD of about 3 ° or less, for example. Thus, the polarization axes can be aligned by unidirectionally aligning the piezoelectric film 15 with the c-axis that is the polarization direction of the piezoelectric crystal. As a result, the electromechanical coupling coefficient and the quality factor Qm of the piezoelectric film 15 can be ensured.

  The piezoelectric film 15 is formed on the surface where the lower electrode 14 is formed on the insulating film 32. At the step between the insulating film 32 and the lower electrode 14, the orientation of the piezoelectric film 15 changes. As a result, there is a problem that stress concentrates on the piezoelectric film 15 and the piezoelectric characteristics are deteriorated or cracks occur in the piezoelectric film 15. In order to alleviate the influence of the stepped portion, the end portion of the lower electrode 14 is inclined so as to have an inclination of 20 degrees or less. In this way, the stress concentration of the piezoelectric film 15 formed on the stepped portion of the inclined lower electrode 14 is relaxed, and the generation of cracks is suppressed.

  According to the first embodiment, it is possible to realize an FBAR that can improve the resonance characteristics and suppress the deterioration of the high-frequency characteristics.

  Next, the FBAR manufacturing method according to the first embodiment will be described with reference to process cross-sectional views shown in FIGS. Here, in the process cross-sectional view used for the description, a cross-section corresponding to the line AA shown in FIG. 1 is shown.

(A) As shown in FIG. 3, an insulating film 32 such as SiO ₂ is formed on the surface of the substrate 11 to a thickness of 1 μm by thermal oxidation or the like.

  (B) While maintaining the temperature of the substrate 11 near room temperature by sputtering or the like, for example, an Al alloy layer, an AlTa amorphous metal layer, and an Al metal layer have thicknesses of about 200 nm, about 100 nm, and about 5 nm, respectively. Form a film. As shown in FIG. 4, the Al metal layer, the AlTa amorphous metal layer, and the Al alloy layer are selectively removed by photolithography, RIE, or the like to remove the first metal film 21, the amorphous metal film 22, and the first metal film. A lower electrode 14 having two metal films 23 is formed. Note that the end of the lower electrode 14 is tilted by adjusting the photolithography conditions to tilt the end of the resist mask.

  (C) A piezoelectric layer such as AlN is formed in a desired thickness by sputtering or the like. As shown in FIG. 5, the piezoelectric film 15 is formed by selectively removing the AlN piezoelectric layer by photolithography, RIE, or the like. The etching of the AlN piezoelectric layer may be wet etching using an alkaline solution.

  (D) An Al alloy layer is formed on the piezoelectric film 15 by sputtering or the like. As shown in FIG. 6, the upper electrode 16 is formed by selectively removing the Al alloy layer by photolithography, wet etching, or the like.

  (E) The back surface of the substrate 11 is polished by polishing or the like, and is thinned to a thickness of about 200 μm, for example. As shown in FIG. 7, the opening is formed by selectively removing the substrate 11 from the back surface using the insulating film 32 as an etching stop layer by photolithography, RIE, or the like. The cavity 17 is formed by selectively removing the insulating film 32 under the lower electrode 14 through the opening of the substrate 11 by wet etching or the like. In this manner, as shown in FIG. 2, the resonance part 20 having the lower electrode 14, the piezoelectric film 15, and the upper electrode 16 is formed on the cavity 17.

  In addition, after forming the Al alloy layer of the first metal film 21, it may be once taken out into the atmosphere and an oxide film may be formed on the surface of the Al alloy layer. By forming a thin surface oxide film on the first metal film 21, it becomes easy to maintain the amorphous structure of the AlTa amorphous metal layer which is the amorphous metal film 22, and as a result, the second metal film 23. The orientation of the thin Al metal film and the AlN piezoelectric layer of the piezoelectric film 15 can be improved.

  Alternatively, the exposed amorphous metal film 22 that is not covered with the piezoelectric film 15 may be removed. The exposed amorphous metal film 22 may be removed by, for example, RIE or chemical dry etching (CDE) after the etching of the piezoelectric film 15.

  In the above description, the first metal film 21 is formed with a thickness of about 200 nm. Since the resistance value of the first metal film 21 is inversely proportional to the thickness, it is desirable to increase the thickness. If a metal material having a low hardness such as Al is thickly formed, the amount of energy absorbed by the piezoelectric resonance vibration generated in the piezoelectric film 15 is increased, which may cause an elastic loss. However, by interposing an amorphous metal film 22 having a generally high hardness between the first metal film 21 and the piezoelectric film 15, vibration energy absorption in the first metal film 21 can be suppressed, and as a result It is possible to increase the thickness of the first metal film 21 without incurring a large elastic loss. An amorphous metal film 22 is formed with a thickness of about 100 nm. The amorphous metal film 22 is also used as an etching stop layer in the etching of the piezoelectric film 15. The etching selectivity of AlN to AlTa varies depending on the etching conditions. For example, AlN and Al are etched by RIE using a chloride gas. AlTa is etched by RIE using a fluoride gas. In RIE using a chloride gas, the etching rate of AlTa is slower than that of AlN and Al. Therefore, the required thickness of the amorphous metal film 22 may be determined in consideration of the etching selectivity of the piezoelectric film 15 with respect to the amorphous metal film 22 and the weight addition effect of the amorphous metal film 22. The amorphous metal film 22 preferably has a thickness of about 3 nm or more in order to ensure flatness.

  The second metal film 23 is formed with a thickness of about 5 nm. The second metal film 23 may have a thickness of about 3 nm or more in order to ensure flatness. However, if the second metal film 23 is too thick, the elastic loss due to energy absorption in the low-hardness Al film constituting the second metal film 23 becomes large, and the quality factor Qm tends to decrease. Therefore, it is desirable to form the second metal film 23 with a thickness of about 10 nm or less.

  Further, the electrode thickness of the lower and upper electrodes 14 and 16 is defined by the resonance frequency of the FBAR and the metal material used for the lower and upper electrodes 14 and 16. If the density of the metal material is small, the electrode thickness increases. Therefore, in order to reduce the resistance of the lower and upper electrodes 14 and 16, it is desirable to use a metal material having a low resistivity and a low density. For example, metals such as Al and Cu, and alloys containing Al, Cu and the like as main components are desirable.

  Further, the resistivity of AlTa used as the amorphous metal film 22 is about two orders of magnitude higher than that of a low resistivity metal such as Al. On the other hand, the thin Al metal film of the second metal film 23 immediately below the piezoelectric film 15 is removed when the AlN piezoelectric layer of the piezoelectric film 15 is etched. However, since the amorphous metal film 22 functions as an etching stop layer in the etching of the piezoelectric film 15, the first metal film 21 under the amorphous metal film 22 is not etched. In the first embodiment, a metal material having a low resistivity and a low density is used as the first metal film 21. Accordingly, the thickness of the first metal film 21 having a low resistivity can be increased to make the lower electrode 14 have a low resistance, and deterioration of resonance characteristics in the high frequency band can be suppressed.

  In the first embodiment, the first metal film 21 and the amorphous metal film 22 are flatly formed on the surface of the insulating film 32. A second metal film 23 such as Al can be formed on the surface of the flat amorphous metal film 22 with a high orientation in the (111) direction. As a result, it is possible to form the piezoelectric film 15 on the surface of the second metal film 23 with the c-axis highly oriented. Further, since the lower electrode 14 is formed so as to cover the cavity 17, the mechanical strength of the piezoelectric film 15 can be improved.

  According to the first embodiment, it is possible to manufacture an FBAR that can improve resonance characteristics and suppress deterioration of high-frequency characteristics.

(Second Embodiment)
As shown in FIGS. 8 and 9, the FBAR according to the second embodiment of the present invention includes the first metal film 21a embedded in the insulating film 32 via the barrier film 34, and the embedded first film. The lower electrode 14 having the amorphous metal film 22 provided on the planarized surface of the metal film 21a and the insulating film 32 and the second metal film 23 provided on the surface of the amorphous metal film 22 is formed. Prepare. Further, the end portion of the lower electrode 14 covered with the piezoelectric film 15 is inclined with respect to the surface of the insulating film 32 at an angle smaller than a right angle. The piezoelectric film 15 extends to the inclined end side of the lower electrode 14. The upper electrode 16 is provided extending on the surface of the piezoelectric film 15. The resonance unit 20 is defined by the lower electrode 14, the piezoelectric film 15, and the upper electrode 16 disposed on the cavity 17.

  The second embodiment is different from the first embodiment in that the first metal film 21a is embedded in the insulating film 32. Other configurations are the same as those of the first embodiment, and thus redundant description is omitted.

  In the second embodiment, the first metal film 21a of the lower electrode 14 is a low-resistance metal film and can suppress the deterioration of the high-frequency characteristics of the FBAR. An oriented second metal film 23 is provided on the amorphous metal film 22 of the lower electrode 14. The piezoelectric film 15 provided on the oriented second metal film 23 can be highly oriented along the c axis. Therefore, the electromechanical coupling coefficient and the quality coefficient Qm of the piezoelectric film 15 can be ensured. Further, the first metal film 21 is embedded in the insulating film 32. Therefore, the step at the inclined end portion of the lower electrode 14 is reduced. Therefore, the stress concentration of the piezoelectric film 15 formed on the step portion of the inclined lower electrode 14 is relieved, and the generation of cracks can be suppressed.

  According to the second embodiment, it is possible to realize an FBAR capable of improving the resonance characteristics and suppressing the deterioration of the high frequency characteristics.

  Next, a method for manufacturing the FBAR according to the second embodiment will be described with reference to process cross-sectional views shown in FIGS.

(A) As shown in FIG. 10, an insulating film 32 such as SiO ₂ is formed to a thickness of 1.3 μm on the surface of the substrate 11 by thermal oxidation or the like. As shown in FIG. 11, the insulating film 32 is selectively removed by photolithography, RIE or the like to form the groove 27. A barrier film 34 such as Si ₃ N _{4 is} formed on the surface of the insulating film 32 having the grooves 27 by chemical vapor deposition (CVD) or the like.

  (B) As shown in FIG. 12, a metal layer such as Cu is formed by sputtering or the like so as to fill the groove 27 in the surface of the barrier film. The metal layer is planarized by CMP or the like so that the surface of the insulating film 32 is exposed, thereby forming the first metal film 21a.

  (C) As shown in FIG. 13, for example, an AlTa amorphous metal layer and an Al metal layer are formed to a thickness of about 100 nm and about 5 nm, respectively, by sputtering or the like. The lower electrode 14 having the first metal film 21a, the amorphous metal film 22 and the second metal film 23 is formed by selectively removing the Al metal layer and the AlTa amorphous metal layer by photolithography, RIE or the like. Form. Note that the edges of the amorphous metal film 22 and the second metal film 23 are tilted by adjusting the photolithography conditions and tilting the edges of the resist mask.

  (D) As shown in FIG. 14, a piezoelectric layer such as AlN is formed to a desired thickness by sputtering or the like. A Cu alloy layer or the like is formed on the piezoelectric film 15 with a thickness of, for example, about 300 nm by sputtering or the like. The upper electrode 16 is formed by selectively removing the Cu alloy layer by photolithography, wet etching, or the like. Subsequently, the AlN piezoelectric layer is selectively removed by photolithography, RIE, or the like to form the piezoelectric film 15.

  (E) The back surface of the substrate 11 is polished, and the film is thinned to a thickness of about 200 μm, for example. As shown in FIG. 15, the opening is formed by selectively removing the substrate 11 from the back surface using the insulating film 32 as an etching stop layer by photolithography, RIE, or the like. The cavity 17 is formed by selectively removing the insulating film 32 and the barrier film 34 under the lower electrode 14 through the opening of the substrate 11 by wet etching or the like. In this way, as shown in FIG. 9, the resonance part 20 having the lower electrode 14, the piezoelectric film 15, and the upper electrode 16 is formed on the cavity 17.

  In the second embodiment, a metal material having a low resistivity and a low density is used as the first metal film 21a. Therefore, the electrode thickness can be increased to reduce the resistance, and deterioration of the resonance characteristics in the high frequency band can be suppressed.

  In the second embodiment, the amorphous metal film 22 is formed flat on the surfaces of the insulating film 32 and the first metal film 21a. A second metal film 23 such as Al can be formed on the surface of the flat amorphous metal film 22 with a high orientation in the (111) direction. As a result, the piezoelectric film 15 can be formed with high orientation on the c-axis. Further, since the lower electrode 14 is formed so as to cover the cavity 17, the mechanical strength of the piezoelectric film 15 can be improved.

  According to the second embodiment, it is possible to manufacture an FBAR that can improve the resonance characteristics and suppress the deterioration of the high-frequency characteristics.

(Other embodiments)
As described above, the first and second embodiments of the present invention have been described. However, it should not be understood that the description and drawings constituting a part of this disclosure limit the present invention. From this disclosure, various alternative embodiments, examples and operational techniques will be apparent to those skilled in the art.

  In the first and second embodiments of the present invention, a single-layer low-resistance metal film is used as the first metal film 21 and the upper electrode 16. However, the first metal film 21 and the upper electrode 16 are not limited to a single-layer metal film. A plurality of metal films may be used as long as low resistance is ensured. For example, the first metal film 21 and the upper electrode 16 may include a load electrode such as a TiW film for adjusting the resonance frequency of the resonance unit 20.

  As described above, the present invention naturally includes various embodiments that are not described herein. Accordingly, the technical scope of the present invention is defined only by the invention specifying matters according to the scope of claims reasonable from the above description.

It is a top view which shows an example of FBAR which concerns on the 1st Embodiment of this invention. It is a figure which shows the AA cross section of FBAR shown in FIG. It is process sectional drawing (the 1) which shows an example of the manufacturing method of FBAR which concerns on the 1st Embodiment of this invention. It is process sectional drawing (the 2) which shows an example of the manufacturing method of FBAR which concerns on the 1st Embodiment of this invention. It is process sectional drawing (the 3) which shows an example of the manufacturing method of FBAR which concerns on the 1st Embodiment of this invention. It is process sectional drawing (the 4) which shows an example of the manufacturing method of FBAR which concerns on the 1st Embodiment of this invention. It is process sectional drawing (the 5) which shows an example of the manufacturing method of FBAR which concerns on the 1st Embodiment of this invention. It is a top view which shows an example of FBAR which concerns on the 2nd Embodiment of this invention. It is a figure which shows the BB cross section of FBAR shown in FIG. It is process sectional drawing (the 1) which shows an example of the manufacturing method of FBAR which concerns on the 2nd Embodiment of this invention. It is process sectional drawing (the 2) which shows an example of the manufacturing method of FBAR which concerns on the 2nd Embodiment of this invention. It is process sectional drawing (the 3) which shows an example of the manufacturing method of FBAR which concerns on the 2nd Embodiment of this invention. It is process sectional drawing (the 4) which shows an example of the manufacturing method of FBAR which concerns on the 2nd Embodiment of this invention. It is process sectional drawing (the 5) which shows an example of the manufacturing method of FBAR which concerns on the 2nd Embodiment of this invention. It is process sectional drawing (the 6) which shows an example of the manufacturing method of FBAR which concerns on the 2nd Embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 Substrate 14 Lower electrode 15 Piezoelectric film 16 Upper electrode 17 Cavity 20 Resonance part 21, 21a 1st metal film 22 Amorphous metal film 23 2nd metal film 27a Groove 32 Insulating film 34 Barrier film

Claims (4)

A first metal film on the substrate;
An amorphous metal film made of tantalum aluminum on the first metal film;
A second metal film oriented on the amorphous metal film in a direction perpendicular to the surface of the amorphous metal film;
A thin film piezoelectric resonator comprising: a piezoelectric film oriented in a direction perpendicular to a surface of the second metal film on the second metal film. 2. The thin film piezoelectric resonator according to claim 1, wherein the first metal film has a resistivity of 10 × 10 ⁻⁸ Ωm or less at room temperature. It said second metal film (111) and (110) thin-film piezoelectric resonator according to claim 1 or 2, characterized in that they are oriented in one orientation. Forming a first metal film on the substrate;
Forming an amorphous metal film on the first metal film;
Forming a second metal film oriented in a direction perpendicular to the surface of the amorphous metal film on the amorphous metal film;
Forming a piezoelectric film oriented in a direction perpendicular to the surface of the second metal film on the second metal film;
A method of manufacturing a thin film piezoelectric resonator comprising selectively removing the piezoelectric film using the amorphous metal film as an etching stop layer.

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