JP2006229611A - Thin film piezoelectric resonance instrument - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a thin film piezoelectric resonance instrument for preventing a thin film piezoelectric resonance element and a filter module configured of those elements from being brought into contact with sealing resin, and for preventing high frequency characteristics from being deteriorated, and for making the size(height) of even this packaged thin film piezoelectric resonance element much smaller than such a case that it is covered with a conventional ceramic package. <P>SOLUTION: The mounted structure of a thin film piezoelectric resonance element is structured so that the upper part of a thin film piezoelectric resonance element can be covered with a metallic film or an organic resin film with a cavity interposed, and that the outside can be sealed with organic resin for sealing. At least one or more communicating cavities connecting the internal cavity and the external sealing resin is provided with a stereoscopic structure with a convex or concave structure on the internal wall, and the ratio of the communicating cavity length of the communicating cavity to the internal diameter radius is set so as to be ranging from 3 to 100. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a thin film piezoelectric resonator, and is used particularly for passive components such as a high frequency band filter and an oscillator.

  In recent years, a radio communication system having a frequency in the GHz band, which is represented by a hot spot service of a mobile phone that has been rapidly spread and a notebook PC that has recently been rising, has been actively developed. The use frequency of these wireless communication systems tends to increase with the request for the amount of information to be transmitted and received, and is practically used up to 5 GHz. In a high-frequency circuit in a wireless communication system, a filter is used in an analog circuit portion. In this high-frequency circuit, a ceramic filter or a SAW filter has been conventionally used, but it is difficult to reduce the size of the circuit with a ceramic filter. Further, these devices are becoming difficult to be applied to a portable radio communication system in the GHz band because it is impossible to make an integrated circuit on Si.

  There is a strong demand for downsizing, thinning, and weight reduction of these high-frequency communication devices. It is very important to manufacture high-frequency communication devices for mobile phones and personal computers (PCs) with the aim of reducing volume so that they can be built in or mounted on PC cards. Generally, wireless devices mounted on these devices are roughly classified into an RF front end unit that processes a high frequency (RF) signal and a baseband unit that performs digital signal processing. Of these, the baseband portion is a portion that performs signal modulation / demodulation by digital signal processing, and can basically be constituted by an LSI chip based on a silicon substrate. For this reason, the height of a baseband part can be easily reduced to less than 1 mm. On the other hand, the RF front end unit is a portion that performs amplification, frequency conversion, and the like using a high-frequency signal as an analog signal. For this reason, a complicated configuration including many passive components such as an oscillator and a filter is required, and it is difficult to configure the RF front end portion only with an LSI chip. Among passive components, a dielectric filter or an LC filter has been conventionally used as a filter. Since these filters filter high-frequency signals using the passband characteristics of a cavity resonator or an LC circuit, it is essentially difficult to reduce the size, and it is extremely difficult to reduce the height to several millimeters or less. For this reason, there has been a limit to the reduction in size and thickness of these high-frequency devices, in particular, volume saving by combining them.

  In order to solve such problems, a thin film piezoelectric resonator (FBAR) is drawing attention. A thin film piezoelectric resonator is a thin film piezoelectric resonator formed by sandwiching a thin film piezoelectric body made of aluminum nitride (AlN) or zinc oxide (ZnO) between two electrodes and straddling a cavity formed in a substrate. This cavity may penetrate to the back surface of the substrate or may be just under the lower electrode. The thin film piezoelectric resonance element confines vibration energy in the piezoelectric film by the action of these cavities, and obtains resonance of the frequency in the thickness direction of the lower electrode in contact with the air layer and the upper electrode and the piezoelectric film.

In addition, instead of the cavity directly under the thin film piezoelectric resonator, a reflector having a high acoustic impedance layer and a low layer alternately stacked with a thickness of λ / 4 of the resonance frequency of the thin film piezoelectric resonator is formed. In some cases, the vibration energy is confined in the piezoelectric film, and the resonance of the frequency is obtained in the thickness direction of the lower electrode, the upper electrode, and the piezoelectric film. This is a reflector using a multilayer film in which tungsten (W) is laminated as a high impedance layer and silicon dioxide (SiO ₂ ) is laminated as a low impedance layer.

  A thickness of 0.5 μm to several μm, which is an easy range for forming these thin film piezoelectric resonance elements, corresponds to a resonance frequency of several GHz, which is advantageous for resonance in the high frequency region of the GHz band. .

  By arranging a plurality of these thin film piezoelectric resonance elements in series or in parallel to form a ladder type filter, it can be used as an RF filter for a mobile communication device. Further, by combining a thin film piezoelectric resonance element, a variable capacitor and an amplifier, it can be used as a voltage controlled oscillator (VCO) of a mobile communication device.

  Since the thin film piezoelectric resonator element is formed as a thin film on a semiconductor substrate, it is very easy to reduce the size and particularly to reduce the volume. In particular, the height can be easily realized with a size of less than 1 mm, which is difficult with an existing filter. It is also easy to mount on a semiconductor substrate together with a transistor, IC, or LSI.

  However, to produce a thin-film piezoelectric resonator element with good characteristics and to make use of its small size, to mount it on a high-frequency module together with an amplifying element such as a transistor, IC, LSI, capacitor, resistor, inductor, etc. In order to confine the resonance energy, it is necessary that only the upper part and the lower part or the upper part of the thin film piezoelectric resonator element are in contact with the air layer. This is because the acoustic impedance of the piezoelectric material and electrodes constituting the thin-film piezoelectric resonance element differs from the acoustic impedance of air by several orders of magnitude, so that the elastic vibration is efficiently reflected at the interface and the energy of the elastic wave is confined in the resonance part. Because it is. Therefore, in the process of forming a thin film piezoelectric resonator, it is important to determine how to form an air layer above and below or one side and how to hermetically seal the whole while leaving the air layer above and below or one side. It becomes a problem.

  Conventionally, a form in which a thin film piezoelectric resonance element is sealed with a ceramic package as shown in FIG. 67 has been taken. In FIG. 67, 001 is a thin film piezoelectric resonance element, 002 is wire bonding, 003 is a ceramic substrate, 004 is a ceramic lid, and 005 is a metal joint between them. When a ceramic package such as this conventional example is used, it is necessary to die-bond the thin film piezoelectric resonator element 001 in a chip carrier type package and then seal it with a lid 004 made of ceramic, metal or the like. The overall thickness of the piezoelectric resonant element increases, making it difficult to reduce the size and thickness of high-frequency devices. In order to reduce the package thickness, there is a method of resin molding instead of these lids, etc., but in the thin film piezoelectric resonance element, cavities necessary for resonance are formed above and below the substrate, or above the substrate, Resin sealing using the resin molding method as it is is a difficult method for maintaining high-frequency characteristics because the cavity is filled.

Further, as described in, for example, Japanese Patent Application Laid-Open No. 2002-274367 (Patent Document 2), a technique of sealing so as to cover a thin film piezoelectric resonance element has been proposed. Had the problem that it was difficult to apply.
JP 2001-211053 A JP 2002-274367 A

  The present invention has been made in view of the above problems, and provides a thin-film piezoelectric resonator having a small size even when packaged without sealing resin flowing into the cavity for housing the thin-film piezoelectric resonator element when resin-sealed. The purpose is to do.

  In order to achieve the above object, the present invention has a structure in which a thin film piezoelectric resonance element of each system is covered with a metal film or an organic resin film across a cavity, and the outside is sealed with a sealing resin. In a thin film piezoelectric resonator, a communication cavity from an internal cavity to an external sealing resin is formed, and this communication cavity is filled in an internal cavity communicating with this in the manufacturing process of the apparatus. It is characterized in that it has a shape structure having a diameter and a total extension in which an etching solvent can penetrate into the substrate and an uncured sealing organic resin cannot penetrate.

  According to the present invention, when resin sealing is performed in the final manufacturing process of a thin film piezoelectric resonator, an uncured sealing organic resin enters the cavity in which the thin film piezoelectric resonator element is mounted and contacts the thin film piezoelectric resonator element. In addition, it is possible to structurally prevent a resonance frequency shift and a decrease in k2 and Q, which indicate the performance of the thin film piezoelectric resonator element, and a thin film piezoelectric resonator device having a small size can be obtained even if it is formed into a thin film package.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  (First Embodiment) A thin film piezoelectric resonator according to a first embodiment of the present invention will be described. First, a plurality of types of thin film piezoelectric resonance elements will be described. FIG. 1 is a plan view of the first thin film piezoelectric resonance element FR, and FIG. 2 is a cross-sectional view taken along the cutting line AA ′ in FIG. FIG. 3 is a plan view of the second thin film piezoelectric resonance element FR, and FIG. 4 is a cross-sectional view taken along the cutting line AA ′ in FIG. FIG. 5 is a plan view of the third thin film piezoelectric resonator element FR, and FIG. 6 is a cross-sectional view taken along the cutting line AA ′ in FIG.

  1 to 6, 011 is a substrate, 012 is a thermal oxide film, 013 is a lower electrode film, 014 is a piezoelectric film, 015 is an upper electrode, 016 is a cavity, 017 is a sacrifice layer etching hole, and 018 is A reflector using a λ / 4 acoustic multilayer film of a low acoustic impedance film and a high acoustic impedance film is shown.

  FIGS. 1 and 2 and FIGS. 3 and 4 show a thin film piezoelectric resonance element having a cavity 016 immediately below the lower electrode 013. In the first thin film piezoelectric resonator element FR shown in FIGS. 1 and 2, a cavity 016 that penetrates to the back surface of the substrate 011 is opened, and the lower electrode film 013, the piezoelectric film 014, and the upper part are formed across the cavity 016. An electrode 015 is formed on the thermal oxide film 012 on the substrate 011. In the second thin film piezoelectric resonator element FR shown in FIGS. 3 and 4, a cavity 016 dug in the substrate 011 is formed, and the lower electrode film 013, the piezoelectric film 014, and the upper part are formed across the cavity 016. An electrode 015 is formed on the thermal oxide film 012 on the substrate 011. The third thin film piezoelectric resonator element FR shown in FIGS. 5 and 6 has high acoustic impedance instead of the cavity 016 directly below the thin film piezoelectric resonator element FR shown in FIGS. 1, 2, 3 and 4. A λ / 4 acoustic multilayer film in which layers and low layers are alternately laminated at a thickness of λ / 4 of the resonance frequency of the above-described thin film piezoelectric resonator element is configured as a reflector 018, on which a lower electrode film 013, a piezoelectric body are formed. A film 014 and an upper electrode 015 are formed across the thermal oxide film 012 on the substrate 011.

  The thin film piezoelectric resonance apparatus of the first embodiment is an RF filter including the first thin film piezoelectric resonance element having the configuration shown in FIGS. 1 and 2, and is shown in FIGS. 7 and 8 in series as will be described later. Or it has nine thin film piezoelectric resonance elements FR1-FR9 connected in parallel. This RF filter uses the second thin film piezoelectric resonator shown in FIGS. 3 and 4 or the third thin film piezoelectric resonator shown in FIGS. 5 and 6 instead of the thin film piezoelectric resonator FR shown in FIGS. Even if used, the same performance is demonstrated.

  7 and 8, a thermal oxide film 2 made of, for example, silicon oxide is provided on a silicon substrate 1, and a lower electrode 3 of a thin film piezoelectric resonance element is provided on the thermal oxide film 2. As will be described later, three lower electrodes 3 are provided, and each lower electrode 3 is configured to be a common lower electrode for the three thin film piezoelectric resonance elements. A lower cavity 4 penetrating the thermal oxide film 2 and the silicon substrate 1 is provided immediately below the lower electrode 3 at a position where each thin film piezoelectric resonance element is provided. A silicon substrate 6 is bonded to the back surface of the silicon substrate 1, that is, the surface opposite to the side on which the thermal oxide film 2 is provided, via a resin layer 5. Therefore, the lower cavity 4 has a structure in which the upper surface is closed by the lower electrode 3 and the bottom surface is closed by the silicon substrate 6.

  On the other hand, a piezoelectric film 7 is provided on the front surface of the silicon substrate 1 provided with the thermal oxide film 2 so as to cover the three lower electrodes 3. On the piezoelectric film 7, there are provided upper electrodes 8 of nine thin film piezoelectric resonance elements which also serve as wirings for connecting the nine thin film piezoelectric resonance elements in series or in parallel. In this embodiment, as will be described later, seven upper electrodes 8 are provided. Further, an insulating film 9 made of, for example, silicon nitride is provided on the piezoelectric film 7 so as to cover these upper electrodes 8. A wiring electrode 10 electrically connected to the upper electrode 8 serving as a terminal of an RF filter in which nine thin film piezoelectric resonance elements are connected in series or in parallel is provided on the side of the piezoelectric film 7. Reference numeral 10 denotes a configuration extending on the thermal oxide film 2.

  Further, a convex metal film 12 is provided so as to cover the nine thin film piezoelectric resonance elements covered with the insulating film 9 and to form the upper cavity 11 between the nine thin film piezoelectric resonance elements. Yes. The metal film 12 closes and seals the communication cavity 13 with a sealing resin, and is electrically insulated from the wiring electrode 10 by an insulating film 14 provided on the side surface and part of the upper surface of the wiring electrode 10.

  Next, a method for manufacturing the thin film piezoelectric resonator according to this embodiment will be described with reference to FIGS. As shown in FIG. 9, first, a lithography technique using a positive resist by forming an Al electrode material film by RF sputtering on a silicon substrate 1 on which a thermal oxide film 2 is formed to a thickness of 1 μm so as to have a thickness of 200 nm. After patterning the electrode material film using, the lower electrode 3 is formed by dry etching using chlorine gas and boron trichloride gas. As the positive resist, a normal commercial product may be used, and OFPR-800 manufactured by Tokyo Ohka Co., Ltd. was used at a resist thickness of 1 μm. A normal magnetron type RIE (Reactive ion etching) apparatus may be used as the dry etcher. In this embodiment, three lower electrodes 3 are formed. Subsequently, as shown in FIG. 10, an aluminum nitride (AlN) film is formed to a thickness of 1 μm as a piezoelectric material so as to cover the lower electrode 3, and a lithography technique using the positive resist described above is used. Then, the piezoelectric material film 7 is formed by patterning the film of the piezoelectric material material with chlorine gas, boron trichloride gas and argon gas using the RIE apparatus described above. The resist film thickness was 2 μm. Next, as shown in FIG. 11, a load is placed on one end of the three lower electrodes 3 for the purpose of making the resonance frequency different between the thin film piezoelectric resonator elements connected in series and the thin film piezoelectric resonator elements connected in parallel. The electrode 15 is formed by sputtering a Mo film with a film thickness of 100 nm, a resist pattern with a film thickness of 1 μm is formed by the above-described lithography method, and is processed by wet etching with hydrogen peroxide for one minute. Thereafter, Al is formed as an electrode material film on the entire surface of the substrate 1 by sputtering so as to have a film thickness of 250 nm, and the electrode material film is patterned using the above-described lithography technique, so that seven pieces are formed as shown in FIG. The upper electrode 8 is formed.

  Thus, nine thin film piezoelectric resonance elements FR1 to FR9 in which the piezoelectric film 7 is sandwiched between the lower electrode 3 and the upper electrode 8 are simultaneously formed. Seven upper electrodes 8 are formed, and one of the seven upper electrodes serves also as a wiring for connecting the thin film piezoelectric resonance element FR2 and the thin film piezoelectric resonance element FR3, and the other upper electrode 8 is a thin film piezoelectric element. It also serves as a wiring for connecting the resonant element FR4 and the thin film piezoelectric resonant element FR5.

  Next, as shown in FIGS. 13 and 14, an Al film having a thickness of 500 nm is formed as an electrode material film on the entire surface of the substrate 1 by sputtering, and the electrode material film is patterned by using the lithography technique described above. Five wiring electrodes 10 respectively connected to the upper electrodes 8 of the thin film piezoelectric resonance elements FR1, FR6, FR7, FR8, FR9 are formed on the sides of the piezoelectric film 7. These wiring electrodes 10 extend not only on the sides of the piezoelectric film 7 but also on the thermal oxide film 2. Thereafter, the back surface of the silicon substrate 1 is polished so that the thickness of the silicon substrate 1 is 50 μm to 200 μm. 13 is a plan view in one manufacturing process of the thin film piezoelectric resonator according to this embodiment, and FIG. 14 is a sectional view taken along the cutting line AA ′ shown in FIG.

  Next, as shown in FIGS. 15 and 16, a film made of silicon nitride (SiNx) is formed on the piezoelectric film 7 using P-CVD (Plasma Chemical Vapor Deposition) so as to cover the upper electrode 8. Then, the passivation film 9 is formed by patterning the silicon nitride film using the lithography technique described above. The passivation film 9 is not formed on the wiring electrode 10. The silicon nitride film was processed by RIE using tetrafluoromethane gas. Thereafter, an insulating film 14 made of, for example, TEOS (tetraethoxysilane) and having a thickness of about 3 μm is formed on the side portion of the wiring electrode 10 by using the above-described lithography technique. The insulating film 14 was processed by the above-described RIE using octafluorocyclobutane gas. The insulating film 14 is for electrically insulating the wiring electrode 10 and the metal film 12 formed in a later process. Most of the wiring electrode 10 extending on the thermal oxide film 2 is not covered with the insulating film 14 but exposed.

  Next, as shown in FIG. 16, by etching from the back surface of the silicon substrate 1 using ICP-RIE (Inductively Coupled Plasma-Reactive Ion Etching), thermal oxidation with silicon immediately below each thin film piezoelectric resonator element FRi is performed. The film 2 is removed. As a result, a lower cavity 4 is formed immediately below each thin film piezoelectric resonance element FRi. Thereafter, a silicon substrate 6 having a thickness of 100 μm to 200 μm is bonded to the back surface of the silicon substrate 2 using a polyimide resin 5 having a thickness of 50 μm. An epoxy resin having moisture resistance may be used instead of the polyimide resin. As a result, the upper surface of the lower cavity 4 is closed by the lower electrode 3 and the bottom surface is closed by the silicon substrate 6.

  Next, as shown in FIGS. 17 and 18, a resist pattern 11 made of a photoresist having a thickness of 5 μm or more is formed so as to cover each thin film piezoelectric resonance element FRi. The resist pattern 11 includes a communication cavity 13. The shape of the communication cavity 13 allows the etching solvent to enter the sacrificial layer resin filled in the internal cavity communicating therewith in the manufacturing process of the apparatus, and allows the uncured sealing organic resin to enter. Have an impossible caliber and total extension. Therefore, in this embodiment, the communication cavity 13 has a pattern in which a convex portion is formed, and an etching solution having a low viscosity used for etching a sacrificial layer of a resist, which will be described later, is sufficiently allowed to flow. High-viscosity epoxy resin or polyimide resin used for resin sealing at the stage takes time to flow in, stops resin penetration in the communication cavity 13, and the thin film piezoelectric resonator element and the convex metal film It has sufficient characteristics to prevent the inflow of resin into the interstices.

In general, the amount of fluid movement in the narrow tube is expressed by the following equation (1) according to the following Hagen-Poiseuille law.

  Where Q: flow rate of the liquid moving in the narrow tube, a: radius of the narrow tube flow path, ΔP: pressure difference applied to the liquid moving in the narrow tube, η: viscosity of the liquid moving in the narrow tube, L: Length.

  From this equation, in order to reduce the amount of movement of the sealing resin into the communication cavity 13, it is preferable to increase the viscosity, decrease the radius of the capillary channel, reduce the pressure difference, and increase the length of the capillary. I understand. Therefore, if the viscosity and pressure difference of the resin are constant, the inflow amount of the resin can be greatly reduced by narrowing and lengthening the narrow tube, and the resin can be prevented from entering the cavity during the resin sealing.

  19 to 21 show details of the communication cavity 13 from a plan view and a sectional view. 19 and 20 show a communication cavity in which convex portions or concave portions are formed. In FIG. 19, a pattern in which convex portions 131 or concave portions 132 are formed in the horizontal direction with a photoresist or the like in the communication cavity 13 having the inner diameter 2a can be formed. The photoresist applied when forming the resist pattern 11 of FIGS. 17 and 18 is formed using a mask having this shape. In FIG. 20, a pattern in which concave portions 132 are formed in the vertical direction with a photoresist or the like in the communication cavity 13 having an inner diameter 2a can be formed. When the resist pattern 11 of FIGS. 17 and 18 is formed, a b1 portion of FIG. 20 is first formed using a non-photosensitive resist using a two-layer resist method or the like. Next, a portion b2 in FIG. 20 is formed using a photosensitive resist. When a positive photosensitive resist is used, the exposed pattern portion is formed as a recess after development. FIG. 21 is obtained by forming the communication cavity 13 having an inner diameter 2a and a total extension L in a folded pattern.

  In order to achieve the above object, when the maximum internal radius of the communication cavity 13 is a and the total extension of the communication cavity 13 is L, the ratio L / a of the maximum internal radius a and the total extension L of the communication cavity 13 is 3 or more. It is only necessary to form a pattern of 200 or less, and the direction of the folded pattern may be parallel or perpendicular to the direction of the communication cavity 13 or a mixed pattern of both. If the ratio L / a is less than 3, the sealing resin reaches the upper cavity through the communication cavity 13 in the sealing resin cure in the sealing process described later, and comes into contact with the thin-film piezoelectric resonator element FR described above. The high frequency characteristics of the piezoelectric resonant element FR and the filter composed of these elements are significantly deteriorated. Further, when L / a exceeds 200, the flow rate in the narrow tube shown in the formula (1) is remarkably reduced. As a result, it becomes very difficult to etch the sacrificial layer when forming the cavity for mounting the thin film piezoelectric resonator element FR. The time required is extremely increased, making it difficult to summarize as industrial manufacturing conditions, and sacrificial layer etching hardly progresses. For this reason, a more preferable condition range is L / a being 5 or more and 150 or less.

  In Example 1 based on the first embodiment, the structure of FIG. 19 is used for the communication cavity 13, L / a is 16, and the ratio of the convex portion to the cross-sectional area is 75%. In the detailed manufacturing method of the structure of FIG. 19, a normal positive photoresist is applied on a wafer so as to have a film thickness of 5 μm, and the meandering pattern 13 having unevenness in the horizontal direction is formed by the above-described lithography method.

Next, as shown in FIGS. 22 and 23, Ti and Au are sequentially laminated by sputtering and plating so as to cover the resist patterns 11 and 13, thereby forming a convex metal film 12 made of Ti / Au. Ti is 10 nm or more, and Au is 500 nm or more. The plating method may be either electroplating or electroless plating as long as it satisfies the film thickness specification, throwing power, and adhesion strength. A metal film 12 made of Ti / Au is formed on the wiring electrode 10 via an insulating film 14 made of TEOS. In a portion other than the resist patterns 11 and 13, a metal film 12 made of Ti / Au is formed via SiO ₂ on the substrate. In addition, the metal film 12 made of Ti / Au is not formed at the exit of the communication cavity 13, and a pattern is formed by the above-described lithography method so that the photoresist 11 is exposed. Ti / Au was removed by etching with an ammonium fluoride aqueous solution and an iodine + potassium iodide aqueous solution, respectively. This exposed portion becomes the opening 19.

  Next, the substrate 1 is immersed in a resist stripping solvent NMP (n-methylpyrodoline) heated to 90 ° C. for about 1 hour, and the resist patterns 11 and 13 in the metal film 12 made of Ti / Au are formed in the opening 19. To dissolve. Thereafter, immersion and cleaning in isopropyl alcohol are repeated three times, followed by drying in 110 ° C. nitrogen. As a result, as shown in FIGS. 24 and 25, the portion from which the resist pattern 11 has been removed becomes the upper cavity 11 ′.

  Next, as shown in FIG. 26, a photosensitive epoxy mold resin 20 as an organic resin for sealing is applied on the convex metal film 12. An RF filter using thin-film piezoelectric resonant elements FR1 to FR9 covered with the convex metal film 12 is formed on the wiring electrode 10 by removing the mold resin by the photolithography technique described above and then curing (curing) the resin. Complete. The curing conditions are 150 ° C. and 1 hour in a nitrogen atmosphere.

  FIG. 27 shows a circuit diagram of the RF filter according to this embodiment. In FIG. 27, an inductor indicates a wire when the wiring electrode 10 and an external terminal are connected by wire bonding. The RF filter has a configuration in which a plurality of thin film piezoelectric resonance elements FR are arranged in series-parallel connection.

  As described above, according to the thin film piezoelectric resonator of the first embodiment, the thin film piezoelectric resonator elements FR1 to FR9 are covered with the convex metal film 12, so that the resin for sealing is used. Even if the molding is performed, it is possible to sufficiently prevent uncured sealing resin from entering the upper cavity where the thin film piezoelectric resonator elements FR1 to FR9 are mounted, and the convex metal film 12 and the thin film piezoelectric resonator element An upper cavity 11 'is formed between FR1 and FR9, and it is possible to prevent the high frequency characteristics such as the thin film piezoelectric resonator elements FR1 to FR9 and the filter module composed thereof from being deteriorated. The size (height) can be greatly reduced compared to the case of covering with a conventional ceramic package.

  (Second Embodiment) Next, a thin film piezoelectric resonator according to a second embodiment of the present invention will be described with reference to FIGS. 28 to 31 are manufacturing process diagrams of the thin film piezoelectric resonator according to the second embodiment. The thin film piezoelectric resonator according to this embodiment is an RF filter including nine thin film piezoelectric resonator elements FR1 to FR9 as in the thin film piezoelectric resonator of the first embodiment. The cavity 111 ′ is formed by the epoxy resin 112, and the steps up to the step of forming the resist pattern 111 are performed using the same steps as in the first embodiment. FIG. 28 is a plan view immediately after forming the resist pattern 111, and FIG. 29 is a cross-sectional view taken along line AA 'in FIG.

  The structure will be briefly described. The structure is almost the same as that of the first embodiment. A thermal oxide film 102 is provided on a silicon substrate 101, and a lower electrode 103 of a thin film piezoelectric resonance element is provided on the thermal oxide film 102. Yes. A lower cavity 104 penetrating the thermal oxide film 102 and the silicon substrate 101 is provided immediately below the lower electrode 103 at a position where each thin film piezoelectric resonance element is provided. A silicon substrate 106 is bonded to the back surface of the silicon substrate 101 via a resin layer 105. A piezoelectric film 107 is provided on the front surface of the silicon substrate 101 provided with the thermal oxide film 102 so as to cover the three lower electrodes 103. On the piezoelectric film 107, there are provided upper electrodes 108 of nine thin film piezoelectric resonator elements that also serve as wirings for connecting the nine thin film piezoelectric resonator elements FR1 to FR9 in series or in parallel. An insulating film 109 is provided on the piezoelectric film 107 so as to cover these upper electrodes 108. On the side of the piezoelectric film 107, there is provided a wiring electrode 110 that is electrically connected to the upper electrode 108 serving as a terminal of an RF filter in which nine thin film piezoelectric resonance elements FR1 to FR9 are connected in series or in parallel. Yes. The steps up to here and the formation of the next insulating film 109 are the same as those in the first embodiment. Further, convex resist patterns 111 and 113 are provided so as to cover the nine thin film piezoelectric resonance elements FR1 to FR9 covered with the insulating film 109.

  In Example 2 based on the second embodiment, the structure shown in FIG. 21 is used for the communication cavity 113 and L / a is set to 85. A method for manufacturing the communication cavity 113 used in this embodiment will be described in detail. After applying the same positive resist as in Example 1 to a film thickness of 10 μm, a pattern having unevenness in the horizontal direction is formed by the above-described lithography method. The cross section of the connection to the outside and the cavity is smaller than the pattern shown in FIG. 19, and a large L / a is easily obtained.

  The steps after forming the resist pattern 111 are as follows. As shown in FIGS. 28 and 29, a photosensitive epoxy resin is applied so as to cover the resist pattern 111, and an epoxy resin film 112 is formed. The epoxy resin film 112 is 1 μm or more. Further, the epoxy resin film 112 is not formed at the exit of the communication cavity 13, and the photoresist is exposed, and this exposed portion becomes the opening 119. The curing condition is preferably 180 ° C. for 30 minutes in a nitrogen atmosphere.

  Next, the substrate is immersed in a resist stripping solvent NMP (n-methylpyrodrin) heated to 90 ° C. for about 1 hour, and the resist patterns 111 and 113 in the epoxy resin film 112 are dissolved from the opening 119. Thereafter, the immersion replacement in isopropyl alcohol is repeated three times and dried as described above, whereby the portion from which the resist pattern 111 has been removed becomes the upper cavity 111 'as shown in FIGS.

  Next, as in the case of the first embodiment shown in FIG. 26, a photosensitive epoxy mold resin is applied onto the convex epoxy resin film 112. An RF filter using the thin film piezoelectric resonator elements FR1 to FR9 covered with the convex epoxy resin film 112 is completed on the wiring electrode 110 by removing the mold resin by photolithography and then curing (curing) the resin. To do. The curing condition is preferably 150 ° C. for 1 hour in a nitrogen atmosphere.

  As described above, according to the second embodiment, since the thin film piezoelectric resonator elements FR1 to FR9 are covered with the convex epoxy resin film 112, resin molding is performed at the time of sealing. However, it is possible to sufficiently prevent uncured sealing resin from entering the inside of the cavity where the thin film piezoelectric resonator elements FR1 to FR9 are mounted, and the convex epoxy resin film 112 and the thin film piezoelectric resonator elements FR1 to FR9. An upper cavity 111 ′ is formed between the thin film piezoelectric resonator elements FR 1 to FR 9 and a filter module composed of these, so that the high frequency characteristics can be prevented from being deteriorated. The size (height) can be greatly reduced compared to the case of covering with a package.

  (Third Embodiment) Next, a thin film piezoelectric resonator according to a third embodiment of the present invention will be described with reference to FIGS. 32 to 40 are sectional views of manufacturing steps of the thin film piezoelectric resonator according to the third embodiment. The thin film piezoelectric resonator according to this embodiment is an RF filter including nine thin film piezoelectric resonator elements FR201 to FR209 as in the thin film piezoelectric resonator of the first embodiment. The thin film piezoelectric resonator element FR having a structure in which a closed cavity 016 is formed below the lower electrode 013 shown in FIGS. 3 and 4 is used. Subsequent steps for forming the wiring electrode 210 are performed using the same steps as those in the first embodiment.

  The thin film piezoelectric resonator of this embodiment is an RF filter provided with the thin film piezoelectric resonator element FR of FIGS. 3 and 4, and is shown in FIGS. 32 and 33 and connected in series or in parallel as will be described later. It has nine thin film piezoelectric resonance elements FR1 to FR9. A thermal oxide film 202 made of, for example, silicon oxide is provided on the silicon substrate 201 of FIGS. 32 and 33, and a lower electrode 203 of a thin film piezoelectric resonance element is provided on the thermal oxide film 202. Under the lower electrode 203, a closed cavity 204 and an etching hole 220 connecting the outside to the outside are formed. Three lower electrodes 203 are provided, and each lower electrode 203 is configured to be a common lower electrode for the three thin film piezoelectric resonance elements.

  On the other hand, a piezoelectric film 207 is provided on the front surface of the silicon substrate 201 provided with the thermal oxide film 202 so as to cover the three lower electrodes 203. On the piezoelectric film 207, there are provided upper electrodes 208 of nine thin film piezoelectric resonance elements that also serve as wirings for connecting the nine thin film piezoelectric resonance elements in series or in parallel. In this embodiment, as will be described later, seven upper electrodes 208 are provided. An insulating film 209 made of, for example, silicon nitride is provided on the piezoelectric film 207 so as to cover these upper electrodes 208. On the side of the piezoelectric film 207, there is provided a wiring electrode 210 that is electrically connected to the upper electrode 208 serving as a terminal of an RF filter in which nine thin film piezoelectric resonance elements FR201 to FR209 are connected in series or in parallel. The wiring electrode 210 extends on the insulating film 207.

  Further, a convex shape is formed so as to cover the nine thin film piezoelectric resonance elements FR201 to FR209 covered with the insulating film 210 and to form an upper cavity 211 ′ between the nine thin film piezoelectric resonance elements FR201 to FR209. A metal film 212 is provided. The metal film 212 is sealed by sealing the communication cavity 213 with a sealing resin in the same manner as in the first and second embodiments, and is provided on the side surface of the wiring electrode 210 and a part of the upper surface. The insulating film 214 is electrically insulated.

  Next, a method for manufacturing the thin film piezoelectric resonator according to this embodiment will be described with reference to FIGS. First, a groove having a depth of 500 nm is formed on the silicon substrate 201 to serve as the cavity 204 and the etching hole 220. The groove was formed by the lithography method described above, and the processing was performed by RIE using octafluorocyclobutane gas. Next, a 1 μm thick thermal oxide film 202 is formed on these surfaces. Next, a Mo film as a sacrificial layer material is formed to a thickness of 700 nm on the entire surface of the thermal oxide film 202 by sputtering, and the surface of the thermal oxide film is polished by CMP using a barrier metal slurry, and the Mo sacrificial layer as shown in FIG. A structure is formed in which the material is filled into the cavities 204 and the grooves of the etching holes 220. As shown in FIG. 34, the grooves of the nine cavities 204 and the nineteen etching holes 220 are connected to each other.

  Next, an electrode material film is formed, and the electrode material film is patterned by using a lithography technique to cover the cavity 204 filled with the Mo sacrificial layer material as shown in FIG. An electrode 203 is formed. As the film forming method, the above-described sputtering method was used. In this embodiment, three lower electrodes 203 are formed as shown in FIG. Subsequently, as shown in FIG. 36, an AlN film is formed so as to cover the lower electrode 203 with a piezoelectric material film thickness of 1 μm, and the piezoelectric material film is formed by using the lithography technique and the dry etching technique described above. The piezoelectric film 207 is formed by patterning.

  Next, for the purpose of making the resonance frequency different between the thin film piezoelectric resonator elements connected in series and the thin film piezoelectric resonator elements connected in parallel, as described above on one end of the three lower electrodes 203 as shown in FIG. A load electrode 215 using Mo having a thickness of 80 nm is formed. Thereafter, Mo is formed as an electrode material film on the entire surface of the substrate 201 so as to have a film thickness of 250 nm, and the electrode material film is patterned using the above-described lithography technique and wet etching technique, as shown in FIG. An upper electrode 208 is formed. As a result, nine thin film piezoelectric resonance elements FR201 to FR209 in which the piezoelectric film 207 is sandwiched between the lower electrode 203 and the upper electrode 208 are formed. In the figure, the thin film piezoelectric resonance elements FR201 to FR209 correspond to a region surrounded by a square. Seven upper electrodes 208 are formed, and one of the seven upper electrodes also serves as a wiring for connecting the thin film piezoelectric resonance element FR202 and the thin film piezoelectric resonance element FR203, and the other upper electrode 208 is a thin film piezoelectric element. It also serves as a wiring for connecting the resonant element FR204 and the thin film piezoelectric resonant element FR205.

  Next, as shown in FIGS. 39 and 40, Al is formed as an electrode material film to a thickness of 500 nm on the entire surface of the substrate 201, and the electrode material film is patterned using the lithography technique and the dry etching technique described above. As a result, five wiring electrodes 210 respectively connected to the upper electrodes 208 of the thin film piezoelectric resonator elements FR201, FR206, FR207, FR208, and FR209 are formed on the sides of the piezoelectric film 207. These wiring electrodes 210 extend not only on the sides of the piezoelectric film 207 but also on the thermal oxide film 202. Thereafter, the back surface of the silicon substrate 201 is polished so that the thickness of the silicon substrate 201 is 50 μm to 200 μm. 39 is a plan view in one manufacturing process of the thin film piezoelectric resonator according to this embodiment, and FIG. 40 is a sectional view taken along the cutting line AA ′ shown in FIG.

  The subsequent steps are performed using the same steps as in the first embodiment until the metal film 212 is formed and the upper cavity 211 ′ is formed. Next, the sacrificial layer Mo in the cavity 204 and the etching hole 220 is removed by the above-described wet etching. The wet etching of the sacrificial layer used the same hydrogen peroxide solution as the load electrode. Also in this embodiment, as in the case of the first embodiment shown in FIG. 26, the outside of the metal film 212 is sealed with a mold resin.

  In Example 3 based on the third embodiment, the structure shown in FIG. 21 was used for the communication cavity 213, and L / a was 10.

  As described above, according to the third embodiment, since the thin film piezoelectric resonator elements FR201 to FR209 are covered with the convex metal film 212, even if resin molding is performed during sealing. It is possible to sufficiently prevent the uncured sealing resin from entering the inside of the cavity where the thin film piezoelectric resonator element is mounted, and between the convex metal film 212 and the thin film piezoelectric resonator elements FR201 to FR209. In the case where the upper cavity 211 'is formed and the high frequency characteristics such as the thin film piezoelectric resonator elements FR201 to FR209 and the filter module composed of these can be prevented from being lowered, and even if packaged, they are covered with a conventional ceramic package The size (height) can be greatly reduced compared to.

  (Fourth Embodiment) Next, a thin film piezoelectric resonator according to a fourth embodiment of the present invention will be described with reference to FIGS. FIGS. 41 to 49 are sectional views of manufacturing steps of the thin film piezoelectric resonator according to the fourth embodiment. The thin film piezoelectric resonator according to this embodiment is an RF filter including nine thin film piezoelectric resonator elements FR301 to FR309 as in the thin film piezoelectric resonator of the first embodiment. 311 ′ is formed, and a thin film piezoelectric resonator element FR having a third structure in which a reflector 018 is formed below the lower electrode 013 shown in FIGS. 5 and 6 is used. Subsequent steps for forming the wiring electrode 310 are performed using the same steps as those in the first embodiment.

  In the thin film piezoelectric resonator of this embodiment, as shown in FIGS. 41 and 42, a thermal oxide film 302 made of silicon oxide is provided on a silicon substrate 301, and the thin film piezoelectric resonant element of the thin film piezoelectric resonator element is formed on the thermal oxide film 302. A lower electrode 303 is provided. Under the lower electrode 303, nine reflectors 304 and a multilayer film composed of a low acoustic impedance film 321 and a high acoustic impedance film 322 are provided. Three lower electrodes 303 are provided, and each lower electrode 303 is configured to be a common lower electrode for the three thin film piezoelectric resonance elements.

  On the other hand, a piezoelectric film 307 is provided on the front surface of the silicon substrate 301 provided with the thermal oxide film 302 so as to cover the three lower electrodes 303. On the piezoelectric film 307, the upper electrodes 308 of the nine thin film piezoelectric resonator elements, which also serve as wirings for connecting the nine thin film piezoelectric resonator elements in series or in parallel, are provided. In this embodiment, as will be described later, seven upper electrodes 308 are provided. An insulating film 309 made of, for example, silicon nitride is provided on the piezoelectric film 307 so as to cover these upper electrodes 308. On the side of the piezoelectric film 307, there is provided a wiring electrode 310 that is electrically connected to an upper electrode 308 serving as a terminal of an RF filter in which nine thin film piezoelectric resonance elements FR301 to FR309 are connected in series or in parallel. The wiring electrode 310 is configured to extend on the thermal oxide film 302.

  Further, a convex shape is formed so as to cover the nine thin film piezoelectric resonance elements FR301 to FR309 covered with the insulating film 309 and to form an upper cavity 311 ′ between the nine thin film piezoelectric resonance elements FR301 to FR309. A metal film 312 is provided. The outside of the metal film 312 is sealed by sealing the communication cavity 313 with a sealing resin as in the case of the first embodiment shown in FIG. It is electrically insulated by an insulating film 314 provided on the upper surface of the part.

Next, a method for manufacturing the thin film piezoelectric resonator according to the fourth embodiment will be described with reference to FIGS. First, grooves having a depth of 3 μm to be the reflectors 304 are formed on the silicon substrate 301, and then a thermal oxide film 302 is formed on these surfaces. The method for forming the groove was the same as in the third embodiment. Next, SiO ₂ 321 having a film thickness of 725 nm as a low acoustic impedance film is formed on the entire surface of the thermal oxide film 302 as a high acoustic impedance film, and a film thickness of 647 nm W 322 and a low acoustic impedance film 321 are alternately alternated at a thickness of λ / 4 of the resonance frequency. The reflector 304 laminated on the surface is laminated and polished to the height of the surface of the thermal oxide film by the above-described CMP, and the low acoustic impedance film 321, the high acoustic impedance film 322, and the low acoustic impedance film 321 as shown in FIG. The multilayer film is filled in the groove of the reflector 304 to form a structure.

  Next, an Al electrode material film is formed to a thickness of 200 nm, and the electrode material film is patterned using the lithography technique and the dry etching technique so as to cover the reflector 304 as shown in FIG. A lower electrode 303 is formed. In this embodiment, three lower electrodes 303 are formed as shown in FIG. Subsequently, as shown in FIG. 45, an AlN film having a film thickness of 1475 nm is formed as a piezoelectric material so as to cover the lower electrode 303, and the film of the piezoelectric material is patterned using the above-described lithography technique and dry etching technique. Thus, the piezoelectric film 307 is formed.

  Next, for the purpose of making the resonance frequency different between the thin-film piezoelectric resonator elements connected in series and the thin-film piezoelectric resonator elements connected in parallel, the above-described one is provided on one end of the three lower electrodes 303 as shown in FIG. Mo load electrode 315 is formed. Thereafter, the Al electrode material film described above is formed on the entire surface of the substrate 301, and the electrode material film is patterned using a lithography technique, thereby forming an upper electrode 308 as shown in FIG. As a result, nine thin film piezoelectric resonance elements FR301 to FR309 in which the piezoelectric film 307 is sandwiched between the lower electrode 303 and the upper electrode 308 are formed. In FIG. 47, the thin film piezoelectric resonance elements FR301 to FR309 are portions corresponding to a region surrounded by a square. Seven upper electrodes 308 are formed, and one of the seven upper electrodes also serves as a wiring for connecting the thin film piezoelectric resonance element FR302 and the thin film piezoelectric resonance element FR303, and the other upper electrode 308 is a thin film piezoelectric element. It also serves as a wiring for connecting the resonant element FR304 and the thin film piezoelectric resonant element FR305.

  Next, an electrode material film is formed on the entire surface of the substrate 301, and the electrode material film is patterned by using a lithography technique, so that the thin film piezoelectric resonator elements FR301, FR306, FR307, FR308 as shown in FIGS. , Five wiring electrodes 310 respectively connected to the upper electrode 308 of the FR 309 are formed on the side portion of the piezoelectric film 307. These wiring electrodes 310 extend not only on the sides of the piezoelectric film 307 but also on the thermal oxide film 302. 48 is a plan view in one manufacturing process of the thin film piezoelectric resonator according to this embodiment, and FIG. 49 is a sectional view taken along the cutting line AA ′ shown in FIG. Thereafter, the back surface of the silicon substrate 301 is polished so that the thickness of the silicon substrate 301 is 50 μm to 200 μm.

  The subsequent steps are performed using the same steps as in the third embodiment until the metal film 312 is formed and the upper cavity 311 ′ is formed.

  In Example 4 based on the fourth embodiment, the structure shown in FIG. 21 is used for the communication cavity 313 and L / a is 55.

  In the fourth embodiment, the outside of the metal film 312 is sealed with a mold resin as in the case of the first embodiment shown in FIG. In this case, a polyimide mold resin is used, and the wiring electrode 310 is processed so that the surface becomes a wiring electrode metal by the above-described lithography. The mold resin is preferably cured at 300 ° C. for 1 hour in a nitrogen atmosphere.

  As described above, according to the fourth embodiment, since the thin film piezoelectric resonator elements FR301 to FR309 are covered with the convex metal film 312, the resin mold at the time of sealing is performed. However, it is possible to sufficiently prevent the uncured sealing resin from entering the cavity in which the thin film piezoelectric resonator elements FR301 to FR309 are mounted, and the convex metal film 312 and the thin film piezoelectric resonator elements FR301 to FR309 An upper cavity 311 ′ is formed between the thin film piezoelectric resonator elements FR 301 to FR 309 and a filter module composed of these thin film piezoelectric resonator elements FR 301 to FR 309. The size (height) can be greatly reduced compared with the case of covering with.

  (Fifth Embodiment) Next, a thin film piezoelectric resonator according to a fifth embodiment of the present invention will be described with reference to FIGS. 50 and 51 are manufacturing process diagrams of the thin film piezoelectric resonator according to the fifth embodiment. The thin film piezoelectric resonator according to this embodiment is formed in the same manner as the thin film piezoelectric resonator of the first embodiment, and uses the same processes as those of the first embodiment except for the structure of the communication cavity 413. Do it. The communication cavity 413 adopts the structure of FIG. In this embodiment, similarly to the third embodiment, the upper cavity 411 ′ is sealed with a mold resin. In this embodiment, the components corresponding to those of the first embodiment are distinguished by attaching 400 symbols. Here, a manufacturing method of the communication cavity 413 will be described in detail. A resist is applied to the surface of the substrate so as to have a film thickness of 5 μm, and a resist film having a b1 structure is formed by the above-described lithography method in FIG. Next, the substrate is baked on a hot plate at 140 ° C. for 3 minutes. Next, a resist is applied to the surface of the substrate so as to have a film thickness of 5 μm, and a resist film having a b2 structure in FIG.

  In Example 5 based on this embodiment, L / a was 13, and the ratio of the recess to the cross-sectional area was 95%.

  As described above, according to the fifth embodiment, since the thin film piezoelectric resonator elements FR401 to FR409 are covered with the convex metal film 412, the resin mold at the time of sealing is performed. However, it is possible to sufficiently prevent the uncured sealing resin from entering the cavity in which the thin film piezoelectric resonator elements FR401 to FR409 are mounted. The convex metal film 412 and the thin film piezoelectric resonator elements FR401 to FR409 An upper cavity 411 ′ is formed between the thin film piezoelectric resonator elements FR 401 to FR 409 and a filter module composed of the thin film piezoelectric resonator elements FR 401 to FR 409. The size (height) can be greatly reduced compared to the case of covering with a package.

  (Sixth Embodiment) Next, a thin film piezoelectric resonator according to a sixth embodiment of the present invention will be described with reference to FIGS. 52 and 53 are manufacturing process diagrams of the thin film piezoelectric resonator according to the sixth embodiment. The thin film piezoelectric resonator according to this embodiment is formed in the same manner as the thin film piezoelectric resonator of the third embodiment, and uses the same steps as those of the third embodiment except for the structure of the communication cavity 513. Do it. However, in FIG. 52 and FIG. 53, the constituent elements are denoted by reference numerals in the 500s so as to be distinguished from the third embodiment. Thin film piezoelectric resonant elements FR501 to FR509 are formed in the same arrangement as in the third embodiment. The communication cavity 513 has the structure shown in FIG. In this embodiment, as in the fifth embodiment, the upper cavity 511 ′ is sealed with a mold resin.

  In Example 6 based on the sixth embodiment, the structure shown in FIG. 21 was used, and L / a was 5.

  As described above, according to the sixth embodiment, since the thin film piezoelectric resonant element is covered with the convex metal film 512, the thin film can be obtained even if resin molding is performed during sealing. It is possible to sufficiently prevent uncured sealing resin from entering the cavity in which the piezoelectric resonator elements FR501 to FR509 are mounted, and between the convex metal film 512 and the thin film piezoelectric resonator elements FR501 to FR509. The upper cavity 511 'is formed, and it is possible to prevent the high frequency characteristics such as the thin film piezoelectric resonator element and the filter module composed thereof from being deteriorated. The size (height) can be greatly reduced.

  (Seventh Embodiment) Next, a thin film piezoelectric resonator according to a seventh embodiment of the present invention will be described with reference to FIGS. 54 and 55 are manufacturing process diagrams of the thin film piezoelectric resonator according to the seventh embodiment. The thin film piezoelectric resonator according to this embodiment is formed in the same manner as the thin film piezoelectric resonator of the third embodiment, and uses the same processes as those of the third embodiment except for the structure of the communication cavity 613. Do it. However, in FIGS. 54 and 55, the components are denoted by reference numerals in the 600s so as to be distinguished from the third embodiment. Thin film piezoelectric resonant elements FR601 to FR609 are formed in the same arrangement as in the third embodiment. The communication cavity 613 has the structure shown in FIG. In this embodiment, as in the fifth embodiment, the upper cavity 611 'is sealed with a mold resin.

  In Example 7 based on this 7th Embodiment, the structure shown in FIG. 19 was used for the communication cavity 613, L / a was 8, and the ratio to the cross-sectional area of a convex part was 30%.

  As described above, according to the seventh embodiment, since the thin film piezoelectric resonator elements FR601 to FR609 are covered with the convex metal film 612, resin molding is performed at the time of sealing. However, it is possible to sufficiently prevent the uncured sealing resin from entering the cavity in which the thin film piezoelectric resonator elements FR601 to FR609 are mounted, and the convex metal film 612 and the thin film piezoelectric resonator elements FR601 to FR609 An upper cavity 611 'is formed between the thin film piezoelectric resonator element and the high frequency characteristics such as a thin film piezoelectric resonator element and a filter module composed of these elements can be prevented, and even when packaged, it is covered with a conventional ceramic package The size (height) can be greatly reduced compared to.

  (Eighth Embodiment) Next, a thin film piezoelectric resonator according to an eighth embodiment of the present invention will be described with reference to FIGS. 56 and 57 are manufacturing process diagrams of the thin film piezoelectric resonator according to the eighth embodiment. The thin film piezoelectric resonator according to this embodiment is formed in the same manner as the thin film piezoelectric resonator of the fifth embodiment, and uses the same processes as those of the fifth embodiment except for the structure of the communication cavity 713. Do it. However, in FIGS. 56 and 57, the components are denoted by reference numerals in the 700s so as to be distinguished from the fifth embodiment. Thin film piezoelectric resonant elements FR701 to FR709 are formed in the same arrangement as in the fifth embodiment. The communication cavity 713 has the structure shown in FIG. In this embodiment, as in the fourth embodiment, the upper cavity 711 'is sealed with a mold resin.

  In Example 8 based on the eighth embodiment, the structure shown in FIG. 21 was used for the communication cavity 713, and L / a was 150.

  As described above, according to the eighth embodiment, since the thin film piezoelectric resonant element is covered with the convex metal film 712, the thin film can be formed even if resin molding is performed during sealing. It is possible to sufficiently prevent uncured sealing resin from entering the cavity in which the piezoelectric resonant elements FR701 to FR709 are mounted, and between the convex metal film 712 and the thin film piezoelectric resonant elements FR701 to FR709. The upper cavity 711 ′ is formed, and it is possible to prevent deterioration of high frequency characteristics such as a thin film piezoelectric resonator element and a filter module composed of these, and even if packaged, it is compared with a case where it is covered with a conventional ceramic package. The size (height) can be greatly reduced.

  (Ninth Embodiment) Next, a thin film piezoelectric resonator according to a ninth embodiment of the present invention will be described with reference to FIGS. 58 and 59 are manufacturing process diagrams of the thin-film piezoelectric resonator according to the ninth embodiment. The thin film piezoelectric resonator according to this embodiment is formed in the same manner as the thin film piezoelectric resonator of the fourth embodiment, and uses the same steps as those of the fourth embodiment except for the structure of the communication cavity 813. Do it. In FIG. 58 and FIG. 59, however, the structural elements are shown with reference numerals in the 800s to distinguish them from the fourth embodiment. Thin film piezoelectric resonator elements FR801 to FR809 are formed in the same arrangement as in the fourth embodiment. The communication cavity 813 has the structure shown in FIG. In this embodiment, similarly to the fourth embodiment, the upper cavity 811 ′ is sealed with a mold resin.

  In Example 9 based on the ninth embodiment, the structure of FIG. 19 was used for the communication cavity 813, L / a was 100, and the proportion of the convex portion in the cross-sectional area was 45%.

  As described above, according to the ninth embodiment, since the thin film piezoelectric resonator elements FR801 to FR809 are covered with the convex metal film 812, resin molding is performed at the time of sealing. However, it is possible to sufficiently prevent the uncured sealing resin from entering the cavity in which the thin film piezoelectric resonator elements FR801 to FR809 are mounted, and the convex metal film 812 and the thin film piezoelectric resonator elements FR801 to FR809, An upper cavity 811 'is formed between them, and it is possible to prevent the high frequency characteristics from deteriorating, such as a thin film piezoelectric resonator element and a filter module comprising these, and even when packaged, it is covered with a conventional ceramic package The size (height) can be greatly reduced compared to.

  (Tenth Embodiment) Next, a thin film piezoelectric resonator according to a tenth embodiment of the present invention will be described with reference to FIGS. 60 and 61 are manufacturing process diagrams of the thin film piezoelectric resonator according to the tenth embodiment. The thin film piezoelectric resonator according to this embodiment is formed in the same manner as the thin film piezoelectric resonator of the fourth embodiment, and uses the same steps as those of the fourth embodiment except for the structure of the communication cavity 913. Do it. However, in FIGS. 60 and 61, the components are denoted by reference numerals 900 in order to distinguish them from the fourth embodiment. Thin film piezoelectric resonant elements FR901 to FR909 are formed in the same arrangement as in the fourth embodiment. The communication cavity 913 has the structure shown in FIG. In this embodiment, as in the fourth embodiment, the upper cavity 911 ′ is sealed with a mold resin.

  In Example 10 based on the tenth embodiment, the structure shown in FIG. 20 was used for the communication cavity 913, L / a was 125, and the proportion of the recess in the cross-sectional area was 60%.

  As described above, according to the tenth embodiment, since the thin film piezoelectric resonator elements FR901 to FR909 are covered with the convex metal film 912, resin molding is performed at the time of sealing. However, it is possible to sufficiently prevent the uncured sealing resin from entering the cavity in which the thin film piezoelectric resonator elements FR901 to FR909 are mounted, and the convex metal film 912 and the thin film piezoelectric resonator elements FR901 to FR90 An upper cavity 911 ′ is formed between them, and it is possible to prevent the high frequency characteristics such as the thin film piezoelectric resonator element and the filter module composed of these elements from being deteriorated. The size (height) can be greatly reduced compared to.

  (Eleventh Embodiment) Next, a thin film piezoelectric resonator according to an eleventh embodiment of the present invention will be described with reference to FIGS. 62 and 63 are manufacturing process diagrams of the thin film piezoelectric resonator according to the eleventh embodiment. The thin film piezoelectric resonator according to this embodiment is formed in the same manner as the thin film piezoelectric resonator according to the fifth embodiment, and uses the same steps as those of the fifth embodiment except for the structure of the communication cavity 1013. Do it. However, in FIGS. 62 and 63, the components are denoted by reference numerals in the 1000s so as to be distinguished from the fifth embodiment. Thin film piezoelectric resonant elements FR1001 to FR1009 are formed in the same arrangement as in the fifth embodiment. The communication cavity 1013 has the structure shown in FIG. In this embodiment, similarly to the fifth embodiment, the upper cavity 1011 ′ is sealed with a mold resin.

  In Example 11 based on the eleventh embodiment, the structure of FIG. 19 was used for the communication cavity 1013, and L / a was 200.

  As described above, according to the eleventh embodiment, since the thin film piezoelectric resonator elements FR1001 to Fr1009 are covered with the convex metal film 1012, the resin mold at the time of sealing is performed. However, it is possible to sufficiently prevent the uncured sealing resin from entering the cavity in which the thin film piezoelectric resonator elements FR1001 to FR1009 are mounted, and the convex metal film 1012 and the thin film piezoelectric resonator elements FR1001 to FR1009. An upper cavity 1011 'is formed between them, and it is possible to prevent the high frequency characteristics such as the thin-film piezoelectric resonator element and the filter module composed thereof from being deteriorated, and even if packaged, it is covered with a conventional ceramic package. Compared to the case, the size (height) can be greatly reduced.

  (Twelfth Embodiment) Next, a thin film piezoelectric resonator according to a twelfth embodiment of the present invention will be described with reference to FIGS. 64 and 65 are manufacturing process diagrams of the thin film piezoelectric resonator according to the twelfth embodiment. The thin film piezoelectric resonator according to this embodiment is formed in the same manner as the thin film piezoelectric resonator of the fifth embodiment, and uses the same processes as those of the fifth embodiment except for the structure of the communication cavity 1113. Do it. However, in FIG. 64 and FIG. 65, the constituent elements are denoted by reference numerals in the 1100 series so as to be distinguished from the fifth embodiment. Thin film piezoelectric resonator elements FR1101 to FR1109 are formed in the same arrangement as in the fifth embodiment. The communication cavity 1113 has the structure shown in FIG. In this embodiment, as in the fifth embodiment, the upper cavity 1111 ′ is sealed with a mold resin.

  In Example 12 based on the twelfth embodiment, the structure shown in FIG. 21 was used for the communication cavity 1113, and L / a was 3.

  As described above, according to the twelfth embodiment, since the thin film piezoelectric resonator elements FR1101 to FR1109 are covered with the convex metal film 1112, the resin mold at the time of sealing is performed. However, it is possible to sufficiently prevent the uncured sealing resin from entering the cavity in which the thin film piezoelectric resonator elements FR1101 to FR1109 are mounted, and the convex metal film 1112 and the thin film piezoelectric resonator elements FR1101 to FR1109 An upper cavity 1111 'is formed between the thin film piezoelectric resonator element and the high frequency characteristics such as a thin film piezoelectric resonator element and a filter module composed of these elements can be prevented, and even when packaged, it is covered with a conventional ceramic package The size (height) can be greatly reduced compared to.

  In the first to twelfth embodiments, the 3.5-stage RF filter having nine thin film piezoelectric resonator elements FR has been described as an example. However, the thin film piezoelectric resonator according to the present invention is not limited to this. It is not something that can be done. For example, as shown in FIG. 66, a thin film piezoelectric resonance element 51, a load capacitor 52, a varicap 53, a feedback resistor 54, a damping resistor 55, and an amplifier 56 are combined to be used as a voltage controlled oscillator 50 of a mobile communication device. be able to.

  In the first to twelfth embodiments, the convex metal film x12 is made of a laminated film made of Ti / Au, a laminated film made of Ti / Ni-B / Au, or made of Ti / Pd / Au. A laminated film made of Ti / Ni / Au, a laminated film made of Ti / Ta / Au, a laminated film made of Ti / Mo / Au, or made of Ti / Pd / Cu / Au Laminated film, Ti / Pd / Cu / Ni / Au laminated film, Ti / Ni / Sn laminated film, Cr / Cu / Au laminated film, Al / Ni laminated film, Ti / Au / Laminated film made of Ti, laminated film made of Ti / Ni / Au / Ti, laminated film made of Ti / Ta / Au / Ta, laminated film made of Ti / Pd / Au / Ti, made of Ti / Mo / Au / Ti Laminated film, Ti / Pd / Cu Laminated film made of Au / Ti, laminated film made of Ti / Pd / Cu / Ni / Au / Ti, laminated film made of Al / Ni / Ti, laminated film made of Ti / Pd / Ni, or Al / Ni / Cu Any of the laminated films made of / AuTi may be used. This makes it possible to withstand use in various atmospheres.

The top view which shows an example of a structure of the thin film piezoelectric resonance element used in embodiment of this invention. Sectional drawing in the cutting line AA 'in FIG. The top view which shows another example of a structure of the thin film piezoelectric resonance element used in embodiment of this invention. FIG. 4 is a cross-sectional view taken along a cutting line AA ′ in FIG. 3. The top view which shows another example of a structure of the thin film piezoelectric resonance element used in embodiment of this invention. FIG. 6 is a cross-sectional view taken along a cutting line AA ′ in FIG. 5. 1 is a plan view of a thin film piezoelectric resonance device according to a first embodiment of the present invention. FIG. 8 is a cross-sectional view taken along a cutting line AA ′ in FIG. 7. The top view which shows the manufacturing process (1) of the thin film piezoelectric resonance apparatus by the 1st Embodiment of this invention. The top view which shows the manufacturing process (2) of the thin film piezoelectric resonance apparatus by the 1st Embodiment of this invention. The top view which shows the manufacturing process (3) of the thin film piezoelectric resonance apparatus by the 1st Embodiment of this invention. The top view which shows the manufacturing process (4) of the thin film piezoelectric resonance apparatus by the 1st Embodiment of this invention. The top view which shows the manufacturing process (5) of the thin film piezoelectric resonance apparatus by the 1st Embodiment of this invention. FIG. 14 is a cross-sectional view taken along a cutting line AA ′ in FIG. 13. Sectional drawing which shows the manufacturing process (6) of the thin film piezoelectric resonance apparatus by the 1st Embodiment of this invention. Sectional drawing which shows the manufacturing process (7) of the thin film piezoelectric resonance apparatus by the 1st Embodiment of this invention. The top view which shows the manufacturing process (8) of the thin film piezoelectric resonance apparatus by the 1st Embodiment of this invention. FIG. 18 is a cross-sectional view taken along a cutting line AA ′ in FIG. 17. The top view and sectional drawing of an example of the communication cavity employ | adopted in the manufacturing process (8) of the thin film piezoelectric resonance apparatus by the 1st Embodiment of this invention. The top view and sectional drawing of another example of the communication cavity employ | adopted in the manufacturing process (8) of the thin film piezoelectric resonance apparatus by the 1st Embodiment of this invention. The top view and sectional drawing of another example of the communication cavity employ | adopted in the manufacturing process (8) of the thin film piezoelectric resonance apparatus by the 1st Embodiment of this invention. The top view which shows the manufacturing process (9) of the thin film piezoelectric resonance apparatus by the 1st Embodiment of this invention. FIG. 23 is a cross-sectional view taken along a cutting line AA ′ in FIG. 22. The top view which shows the manufacturing process (10) of the thin film piezoelectric resonance apparatus by the 1st Embodiment of this invention. FIG. 25 is a cross-sectional view taken along a cutting line AA ′ in FIG. 24. Sectional drawing which shows the manufacturing process (11) of the thin film piezoelectric resonance apparatus by the 1st Embodiment of this invention. The circuit diagram of RF filter which employ | adopted the thin film piezoelectric resonance apparatus of the said 1st Embodiment. The top view which shows the manufacturing process (1) of the thin film piezoelectric resonance apparatus by the 2nd Embodiment of this invention. FIG. 29 is a cross-sectional view taken along a cutting line AA ′ in FIG. 28. The figure top view which shows the manufacturing process (2) of the thin film piezoelectric resonance apparatus by the 2nd Embodiment of this invention. FIG. 31 is a cross-sectional view taken along a cutting line AA ′ in FIG. 30. The top view which shows the manufacturing process (1) of the thin film piezoelectric resonance apparatus by the 3rd Embodiment of this invention. FIG. 33 is a cross-sectional view taken along a cutting line AA ′ in FIG. 32. The top view which shows the manufacturing process (2) of the thin film piezoelectric resonance apparatus by the 3rd Embodiment of this invention. The top view which shows the manufacturing process (3) of the thin film piezoelectric resonance apparatus by the 3rd Embodiment of this invention. The top view which shows the manufacturing process (4) of the thin film piezoelectric resonance apparatus by the 3rd Embodiment of this invention. The top view which shows the manufacturing process (5) of the thin film piezoelectric resonance apparatus by the 3rd Embodiment of this invention. The top view which shows the manufacturing process (6) of the thin film piezoelectric resonance apparatus by the 3rd Embodiment of this invention. The top view which shows the manufacturing process (7) of the thin film piezoelectric resonance apparatus by the 3rd Embodiment of this invention. FIG. 40 is a cross-sectional view taken along a cutting line AA ′ in FIG. 39. The top view which shows the manufacturing process (1) of the thin film piezoelectric resonance apparatus by the 4th Embodiment of this invention. FIG. 42 is a cross-sectional view taken along a cutting line AA ′ in FIG. 41. The top view which shows the manufacturing process (2) of the thin film piezoelectric resonance apparatus by the 4th Embodiment of this invention. The top view which shows the manufacturing process (3) of the thin film piezoelectric resonance apparatus by the 4th Embodiment of this invention. The top view which shows the manufacturing process (4) of the thin film piezoelectric resonance apparatus by the 4th Embodiment of this invention. The top view which shows the manufacturing process (5) of the thin film piezoelectric resonance apparatus by the 4th Embodiment of this invention. The top view which shows the manufacturing process (6) of the thin film piezoelectric resonance apparatus by the 4th Embodiment of this invention. The top view which shows the manufacturing process (7) of the thin film piezoelectric resonance apparatus by the 4th Embodiment of this invention. FIG. 49 is a cross-sectional view taken along a cutting line AA ′ in FIG. 48. The top view which shows the manufacturing process of the thin film piezoelectric resonance apparatus by the 5th Embodiment of this invention. FIG. 51 is a cross-sectional view taken along a cutting line AA ′ in FIG. 50. The top view which shows the manufacturing process of the thin film piezoelectric resonance apparatus by the 6th Embodiment of this invention. FIG. 53 is a cross-sectional view taken along a cutting line AA ′ in FIG. 52. The top view which shows the manufacturing process of the thin film piezoelectric resonance apparatus by the 7th Embodiment of this invention. FIG. 55 is a cross-sectional view taken along a cutting line AA ′ in FIG. 54. The top view which shows the manufacturing process of the thin film piezoelectric resonance apparatus by the 8th Embodiment of this invention. FIG. 57 is a cross-sectional view taken along a cutting line AA ′ in FIG. 56. The top view which shows the manufacturing process of the thin film piezoelectric resonance apparatus by the 9th Embodiment of this invention. FIG. 59 is a cross-sectional view taken along a cutting line AA ′ in FIG. 58. The top view which shows the manufacturing process of the thin film piezoelectric resonance apparatus by the 10th Embodiment of this invention. FIG. 61 is a cross-sectional view taken along a cutting line AA ′ in FIG. 60. The top view which shows the manufacturing process of the thin film piezoelectric resonance apparatus by the 11th Embodiment of this invention. FIG. 63 is a cross-sectional view taken along a cutting line AA ′ in FIG. 62. The top view which shows the manufacturing process of the thin film piezoelectric resonance apparatus by the 12th Embodiment of this invention. FIG. 65 is a cross-sectional view taken along a cutting line AA ′ in FIG. 64. The circuit diagram of the voltage controlled oscillator using the thin film piezoelectric resonance apparatus of this invention. Sectional drawing which shows the thin film piezoelectric resonance apparatus of a prior art example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Silicon substrate 2 Thermal oxide film 3 Lower electrode 4 Cavity 5 Adhesive resin 6 Silicon substrate 7 Piezoelectric film 8 Upper electrode 9 Insulating film (SiNx film)
10 Wiring electrode 11 Upper cavity 12 Convex metal film 13 Connection cavity 14 Insulating film (TEOS film)
FR1 to FR9 Thin film piezoelectric resonator element 101 Silicon substrate 102 Thermal oxide film 103 Lower electrode 104 Cavity 105 Adhesive resin 106 Silicon substrate 107 Piezoelectric film 108 Upper electrode 109 Insulating film (SiNx film)
110 Wiring electrode 111 Upper cavity 112 Convex resin film 113 Connection cavity 114 Insulating film (TEOS film)
FR101 to FR109 Thin film piezoelectric resonance element 201 Silicon substrate 202 Thermal oxide film 203 Lower electrode 204 Cavity 207 Piezoelectric film 208 Upper electrode 209 Insulating film (SiNx film)
210 Wiring electrode 211 Upper cavity 212 Convex metal film 213 Connection cavity 214 Insulating film (TEOS film)
220 Etching holes FR201 to FR209 Thin film piezoelectric resonator 301 Silicon substrate 302 Thermal oxide film 303 Lower electrode 304 Cavity 307 Piezoelectric film 308 Upper electrode 309 Insulating film (SiNx film)
310 Wiring electrode 311 Upper cavity 312 Convex metal film 313 Connection cavity 314 Insulating film (TEOS film)
321 Low acoustic impedance film 322 High acoustic impedance film FR301 to FR309 Thin film piezoelectric resonator element 401 Silicon substrate 402 Thermal oxide film 403 Lower electrode 404 Cavity 405 Adhesive resin 406 Silicon substrate 407 Piezoelectric film 408 Upper electrode 409 Insulating film (SiNx film)
410 Wiring electrode 411 Upper cavity 412 Convex metal film 413 Connection cavity 414 Insulating film (TEOS film)
FR401 to FR409 Thin film piezoelectric resonance element 501 Silicon substrate 502 Thermal oxide film 503 Lower electrode 504 Cavity 507 Piezoelectric film 508 Upper electrode 509 Insulating film (SiNx film)
510 Wiring electrode 511 Upper cavity 512 Convex metal film 513 Connection cavity 514 Insulating film (TEOS film)
520 Etching holes FR501 to FR509 Thin film piezoelectric resonance element 601 Silicon substrate 602 Thermal oxide film 603 Lower electrode 604 Cavity 607 Piezoelectric film 608 Upper electrode 609 Insulating film (SiNx film)
610 Wiring electrode 611 Upper cavity 612 Convex metal film 613 Connection cavity 614 Insulating film (TEOS film)
620 Etching holes FR601 to FR609 Thin film piezoelectric resonator element 701 Silicon substrate 702 Thermal oxide film 703 Lower electrode 704 Cavity 705 Adhesive resin 706 Silicon substrate 707 Piezoelectric film 708 Upper electrode 709 Insulating film (SiNx film)
710 Wiring electrode 711 Upper cavity 712 Convex metal film 713 Connection cavity 714 Insulating film (TEOS film)
FR701 to FR709 Thin film piezoelectric resonance element 801 Silicon substrate 802 Thermal oxide film 803 Lower electrode 804 Cavity 807 Piezoelectric film 808 Upper electrode 809 Insulating film (SiNx film)
810 Wiring electrode 811 Upper cavity 812 Convex metal film 813 Connection cavity 814 Insulating film (TEOS film)
821 Low acoustic impedance film 822 High acoustic impedance film FR801 to FR809 Thin film piezoelectric resonator element 901 Silicon substrate 902 Thermal oxide film 903 Lower electrode 904 Cavity 907 Piezoelectric film 908 Upper electrode 909 Insulating film (SiNx film)
910 Wiring electrode 911 Upper cavity 912 Convex metal film 913 Connection cavity 914 Insulating film (TEOS film)
921 Low acoustic impedance film 922 High acoustic impedance film FR901 to FR909 Thin film piezoelectric resonator element 1001 Silicon substrate 1002 Thermal oxide film 1003 Lower electrode 1004 Cavity 1005 Adhesive resin 1006 Silicon substrate 1007 Piezoelectric film 1008 Upper electrode 1009 Insulating film (SiNx film)
1010 Wiring electrode 1011 Upper cavity 1012 Convex metal film 1013 Connection cavity 1014 Insulating film (TEOS film)
FR1001 to FR1009 Thin film piezoelectric resonance element 1101 Silicon substrate 1102 Thermal oxide film 1103 Lower electrode 1104 Cavity 1105 Adhesive resin 1106 Silicon substrate 1107 Piezoelectric film 1108 Upper electrode 1109 Insulating film (SiNx film)
1110 Wiring electrode 1111 Upper cavity 1112 Convex metal film 1113 Connection cavity 1114 Insulating film (TEOS film)
FR1101 to FR1109 Thin Film Piezoelectric Resonator

Claims (5)

A thin-film piezoelectric resonator comprising a first substrate having a through-hole, and a lower electrode, a piezoelectric film, and an upper electrode formed in this order on the opening of the through-hole on the surface of the first substrate; A sealing body formed above the thin film piezoelectric resonator element,
The communication cavity formed by the gap between the thin film piezoelectric resonance element and the sealing body and connected to the through hole is a folded pattern in which the ratio of the maximum internal radius to the total extension is 3 or more and 200 or less. A thin film piezoelectric resonance device characterized by the above. A thin-film piezoelectric resonator comprising a substrate having a multilayer surface of a low acoustic impedance film and a high impedance film on its surface, and a lower electrode, a piezoelectric film and an upper electrode formed in this order on the multilayer film And a sealing body formed above the thin film piezoelectric resonance element,
The communication cavity whose one end communicates with the gap formed by the thin film piezoelectric resonator element and the sealing body and whose other end is closed by the sealing body has a ratio between its maximum internal radius and its total extension. A thin-film piezoelectric resonance device, wherein the thin-film piezoelectric resonator has a folded pattern of 3 or more and 200 or less.   In the place where the convex or concave three-dimensional structure is formed on the inner wall surface of the communication cavity, the ratio of the area of the three-dimensional structure portion of the convex or concave structure to the maximum cross-sectional area of the communication cavity is 30. The thin film piezoelectric resonance device according to claim 1, wherein the thin film piezoelectric resonance device is equal to or greater than% and equal to or less than 95%.   4. The thin film piezoelectric resonator according to claim 1, further comprising: a second substrate disposed on the back surface of the substrate so as to cover the opening of the through hole on the back surface of the first substrate. A wiring electrode is formed on the first substrate so as not to interfere with the communication cavity along the side of the piezoelectric film and the upper surface of the first substrate, and the wiring electrode is connected to the upper electrode. The thin film piezoelectric resonance device according to claim 1, wherein the thin film piezoelectric resonance device is provided.

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