JP4904737B2 - A method for manufacturing an IC-integrated thin-film vibrating piece. - Google Patents

Description

  The present invention relates to a method of manufacturing a thin film vibrating piece in which an electrode and a piezoelectric thin film are formed on a substrate such as a silicon substrate.

  In general, surface acoustic wave devices that form resonators, filters, and the like are used for communication equipment and various signal processing. As this surface acoustic wave device, a surface acoustic wave device using a thin film vibrating piece in which a piezoelectric thin film such as a ZnO thin film is formed on a substrate such as a silicon substrate has been proposed (for example, Patent Document 1 and Patent Document 1). 2).

  Details of the thin-film vibrating piece will be described with reference to the drawings. FIG. 6 is a front sectional view showing a conventional thin film vibrating piece. As shown in FIG. 6, in the thin film vibrating piece 100, an electrode 102 is formed on a silicon substrate 101, and a piezoelectric thin film 103 is formed on the silicon substrate 101 including the surface of the electrode 102. On the piezoelectric thin film 103, an IDT (interdigital converter, for example, an excitation electrode such as a comb electrode) 105 and a reflector 104 are formed. The IDT 105 and the reflector 104 are connected to the electrode 102 by a connection wiring 106. The electrode 102 is connected to an oscillation circuit (not shown), various signal processing circuits, and the like.

  Next, a method for manufacturing the thin film vibrating piece 100 will be described. First, an electrode 102 made of, for example, conductive aluminum is formed on the silicon substrate 101 by using a vapor deposition method, an etching method, or the like. Next, a piezoelectric thin film 103 such as a ZnO thin film is formed on the silicon substrate 101 including the electrode 102. The piezoelectric thin film 103 is formed by using, for example, a vapor deposition method. Next, in order to improve the film quality of the piezoelectric thin film 103, a high temperature treatment of about 300 ° C. to 500 ° C. is performed. Next, electrodes for exciting surface acoustic waves such as IDT 105 and reflector 104 are formed on the piezoelectric thin film 103.

JP 2000-151451 A Japanese Utility Model Publication No. 3-24719

However, in the conventional method of manufacturing the thin film vibrating piece 100 described above, the electrode 102 constituting the thin film vibrating piece 100 and the piezoelectric thin film 103 formed on the electrode 102 are heated to about 300 ° C. to 500 ° C. in a high temperature treatment process. Heated. Since the electrode 102 and the piezoelectric thin film 103 have different coefficients of thermal expansion, different amounts of deformation are caused by heating. For example, the thermal expansion coefficient of the electrode 102 formed of aluminum is 23.1 × 10 ⁻⁶ / ° C., and the thermal expansion coefficient of the piezoelectric thin film 103 formed of ZnO is 4 × 10 ⁻⁶ / ° C. is there. That is, the electrode 102 is deformed by thermal expansion five times or more as compared with the piezoelectric thin film 103. As described above, since the electrode 102 is deformed more greatly than the piezoelectric thin film 103, the piezoelectric thin film 103 formed on the electrode 102 cannot withstand the deformation, and may be cracked or peeled off. The peeled piezoelectric thin film 103 contaminates the surface of the substrate 101, the piezoelectric thin film 103, and the like, and there is a problem that the excitation electrode is lost due to the contamination.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a method for manufacturing a thin-film vibrating piece capable of performing heating and cooling such as high-temperature treatment without causing cracking and peeling of the piezoelectric thin film. Another object of the present invention is to provide a thin film vibrating piece, a thin film vibrator, and a piezoelectric oscillator.

  In order to solve such a problem, the method for manufacturing a thin-film vibrating piece according to the present invention includes a thin-film vibration in which an electrode part and a piezoelectric thin film having a thermal expansion coefficient different from the thermal expansion coefficient of the electrode part are formed on a substrate. A method of manufacturing a piece, comprising: forming the electrode part on the substrate; forming an amorphous thin film on at least the surface of the electrode part; and the substrate including the surface of the amorphous thin film The method includes a step of forming the piezoelectric thin film and an annealing step of treating the piezoelectric thin film at a high temperature.

  According to the method for manufacturing a thin film vibrating piece of the present invention, an amorphous thin film is formed on the surface of an electrode portion formed on a substrate, and a piezoelectric thin film is formed on the surface of the amorphous thin film. That is, an amorphous thin film is formed between the electrode portion and the piezoelectric thin film. An amorphous thin film has a structure in which atomic arrangement is disorderly arranged, so that atoms easily move into gaps, and thus has a tenacious and tough property. Due to the tenacious and tough nature of this amorphous thin film, the difference in deformation between the electrode and piezoelectric thin film with different coefficients of thermal expansion caused by temperature changes such as heating and cooling when the thin film vibrating piece is processed at high temperature To absorb. That is, the amorphous thin film acts as a buffer against deformation due to thermal change, and the deformation of the electrode portion is prevented from affecting the piezoelectric thin film. Therefore, even if the piezoelectric thin film is processed at a high temperature, it is possible to prevent the piezoelectric thin film from being cracked or peeled off due to a difference in deformation due to a difference in thermal expansion coefficient between the electrode portion and the piezoelectric thin film. As a result, it is possible to prevent occurrence of defects in the excitation electrode due to the peeled piezoelectric thin film contaminating the surface of the substrate or the piezoelectric thin film.

  The thermal expansion coefficient of the amorphous thin film is preferably smaller than the thermal expansion coefficient of the electrode part.

  In this way, the amount of deformation of the amorphous thin film, which is relatively small due to heating and cooling for high temperature treatment, is transmitted to the piezoelectric thin film as compared with the electrode portion. The effect of deformation is reduced. That is, it is possible to provide a thin-film vibrating piece in which the piezoelectric thin film is not easily cracked or peeled off due to a large deformation amount of the electrode portion.

  The thin-film vibrating piece of the present invention is manufactured using the above-described method for manufacturing a thin-film vibrating piece.

  According to the thin film vibrating piece of the present invention, even when the thin film vibrating piece is processed at a high temperature, the piezoelectric thin film is cracked or peeled off due to a difference in deformation due to a difference in thermal expansion coefficient between the electrode portion and the piezoelectric thin film. It is possible to provide a thin-film vibrating piece that does not cause the problem.

  The thin-film vibrator of the present invention includes a cage and a thin-film vibrating piece manufactured using the above-described method for manufacturing a thin-film vibrating piece connected to the holder.

  According to the thin film vibrator of the present invention, even if the thin film vibrator is processed at a high temperature, a difference in deformation due to a difference in thermal expansion coefficient between the electrode portion of the thin film vibrating piece used and the piezoelectric thin film is caused. It is possible to provide a thin film vibrator that does not cause cracking or peeling of the piezoelectric thin film.

  The piezoelectric oscillator of the present invention includes a cage, a thin-film vibrating piece manufactured using the method for manufacturing a thin-film vibrating piece connected to the cage, and at least connected to the cage and the thin-film vibrating piece. And a circuit unit having a function of exciting the thin-film vibrating piece.

  According to the piezoelectric oscillator of the present invention, even if the piezoelectric oscillator is processed at a high temperature, the piezoelectric body caused by the difference in deformation due to the difference in thermal expansion coefficient between the electrode portion of the thin film vibrating piece used and the piezoelectric thin film It is possible to provide a piezoelectric oscillator that does not cause cracking or peeling of the thin film.

The best mode of a method for manufacturing a thin film vibrating piece, a thin film vibrating piece, a thin film vibrator, and a piezoelectric oscillator according to the present invention will be described below with reference to the drawings.
(First embodiment)

  As a first embodiment, a manufacturing method of a thin film vibrating piece according to the present invention and a thin film vibrating piece using the manufacturing method will be described with reference to the drawings. FIG. 1 shows a thin film surface acoustic wave resonator element as an example of the thin film resonator element of the present invention, in which (a) is a plan view and (b) is a front sectional view. FIG. 2 is a process flow diagram showing a method of manufacturing a thin film surface acoustic wave resonator element as an example of the thin film resonator element of the present invention.

First, the configuration of the thin film surface acoustic wave resonator element 10 will be described. As shown in FIG. 1, for example, a PAD electrode 12 using, for example, aluminum (Al), copper (Cu), or the like as an electrode portion is formed on a substrate 11 such as silicon (Si). The PAD electrode 12 of this example is made of aluminum (Al) and has a thickness of about 0.6 μm. For example, a silicon oxide (SiO ₂ ) thin film (hereinafter referred to as an amorphous thin film) is formed on the substrate 11 where the PAD electrode 12 is not formed and on the upper surface of a wiring or the like extending from the PAD electrode 12 (not shown). , “SiO ₂ thin film”) 13 is formed. The SiO ₂ thin film 13 is formed with a thickness of about 1 μm. On the SiO ₂ thin film 13, for example, a zinc oxide (ZnO) thin film (hereinafter referred to as “ZnO thin film”) 14 as a piezoelectric thin film is formed. The ZnO thin film 14 is formed with a thickness of about 2 μm.

  On the upper surface of the ZnO thin film 14, comb-tooth electrodes 16a and 16b constituting the excitation electrode 16 for exciting the surface acoustic wave, reflection electrodes 17a and 17b constituting the reflector 17, and bus bars 18a, 18b, 19a and 19b are formed. Has been. Each of the comb-tooth electrodes 16a and 16b is formed in a comb-like shape by providing a plurality of comb-tooth electrodes, and the comb-tooth electrodes 16a and the comb-tooth electrodes 16b are alternately arranged in a propagation direction (left-right direction in the drawing) of the surface acoustic wave at regular intervals. Has been. And the comb-tooth electrode 16a is connected by the bus-bar 18a, and the comb-tooth electrode 16b is connected by the bus-bar 18b, and the excitation electrode 16 is comprised. A plurality of the reflective electrodes 17a and 17b are arranged at the predetermined intervals in the propagation direction. The reflective electrode 17a is connected to the bus bar 19a and the reflective electrode 17b is connected to the bus bar 19b to constitute a reflector (so-called grating reflector) 17. Is done. The reflection electrodes 17a and 17b are respectively arranged on both sides in the propagation direction of the arrangement region of the comb electrodes 16a and 16b.

The ZnO thin film 14 is provided with six openings 15. The opening 15 is formed so as to penetrate the portion of the ZnO thin film 14 and the SiO ₂ thin film 13 facing the PAD electrode 12. Therefore, the end surfaces of the SiO ₂ thin film 13 and the ZnO thin film 14 are exposed on the inner wall surface of the opening 15. By forming the opening 15, the PAD electrode 12 is exposed on the upper surface of the thin film surface acoustic wave vibrating piece 10. The number of openings 15 is determined by the number of PAD electrodes 12 that need to be exposed, and the number thereof may be any number. The PAD electrode 12 is used, for example, to connect the thin film surface acoustic wave vibrating piece 10 to an element other than the thin film surface acoustic wave vibrating piece 10 by connection means such as wire bonding (not shown). The PAD electrode 12 can also be used for connection with the excitation electrode 16, the reflector 17, and the like.

  In addition, although the board | substrate 11 demonstrated silicon (Si) as an example, it is not restricted to this. For example, it may be composed of a semiconductor substrate made of a compound semiconductor (GaAs, GaP, InP, SiGe, ZnS, etc.), a glass substrate, a quartz substrate, a ceramic substrate, or the like.

  Moreover, although the zinc oxide (ZnO) thin film was demonstrated as an example as a piezoelectric material thin film, it is not restricted to this. For example, various piezoelectric thin films that can excite surface acoustic waves such as AlN, PZT (Pb—Zr—Ti), CdS, ZnS, Bi—Pb—O, LiNbO 3, TaNbO 3, and KNbO 3 may be used.

Moreover, although the silicon oxide (SiO ₂ ) thin film has been described as an example of the amorphous thin film, the present invention is not limited to this. For example, sapphire, titanium oxide (TiO ₂ ), or the like can be used.

When the SiO ₂ thin film 13 is not provided on the entire surface of the substrate 11, the ZnO thin film 14 is formed on the substrate 11 and the upper surface of the SiO ₂ thin film 13. Further, the ZnO thin film 14 may not be provided on the entire surface of the substrate 11.

  Next, a manufacturing method of the thin film surface acoustic wave resonator element 10 will be described along a process flow shown in FIG. First, as shown in FIG. 2A, a PAD electrode 12 as an electrode portion is formed on the upper surface of the substrate 11 with a thickness of about 0.6 μm. The PAD electrode 12 is formed by forming an aluminum (Al) thin film on the upper surface of the substrate 11 by vapor deposition or the like, and forming the aluminum thin film by photolithography or the like. Although not shown in the figure, electrodes other than the PAD electrode 12 such as wirings and connection electrodes as electrode portions are formed at the same time.

Next, as shown in FIG. 2B, a SiO ₂ thin film 13 is formed so as to cover the upper surface of the substrate 11 and the PAD electrode 12. The SiO ₂ thin film 13 is formed using a sputtering method, a vapor deposition method, or the like. The SiO ₂ thin film 13 is desirably formed with a thickness of about 0.1 to ₂ μm, but in this example, it is formed with a thickness of 1 μm. The thickness of the SiO ₂ thin film 13 represents the thickness from the surface of the PAD electrode 12.

Next, as shown in FIG. 2C, a ZnO thin film 14 is formed on the upper surface of the SiO ₂ thin film 13. The ZnO thin film 14 is formed using a sputtering method, a vapor deposition method, or the like. The ZnO thin film 14 is formed with an appropriate thickness according to its material and crystallinity. For example, the thickness is generally about 0.1 to 5 μm, and in this example, the thickness is 2 μm.

  Here, the reason why it is desirable that the thickness of the piezoelectric thin film taking the ZnO thin film 14 as an example is within a predetermined range will be described. If the piezoelectric thin film is too thin, the surface acoustic wave propagation mode is easily affected by the lower layer, and the surface of the piezoelectric thin film (upper surface in the illustrated example) has insufficient crystallinity or has sufficient piezoelectric characteristics. May not show the correct size. Usually, it is desirable that the thickness of the piezoelectric thin film be one or more wavelengths of the excited surface acoustic wave. Conversely, if the piezoelectric thin film is too thick, the manufacturing process takes time and the manufacturing cost increases, so that the merit of the thin film surface acoustic wave device is reduced.

  Then, in order to improve the film quality of the formed ZnO thin film 14, a high temperature process of about 300 ° C. to 500 ° C. is performed. This high temperature treatment can be performed using a so-called lamp annealing method or the like in which the ZnO thin film 14 is irradiated with lamp light to bring the ZnO thin film 14 into a high temperature state.

  Next, as shown in FIG. 2D, for example, an aluminum (Al) thin film 20 for forming the excitation electrode 16 and the reflector 17 is formed on the upper surface of the ZnO thin film 14. The aluminum (Al) thin film 20 is formed using a sputtering method, a vapor deposition method, or the like.

Next, as shown in FIG. 2E, the excitation electrode 16 and the reflector 17 are formed. The excitation electrode 16 and the reflector 17 are formed using a photolithography method using a mask made of a resist or the like (not shown). Next, the ZnO thin film 14 and the SiO ₂ thin film 13 corresponding to the PAD electrode 12 are removed, and an opening 15 for exposing the PAD electrode 12 is formed. The opening 15 is formed using a photolithography method or the like as described above. Therefore, the end surfaces of the SiO ₂ thin film 13 and the ZnO thin film 14 are exposed on the inner wall surface of the opening 15.

Here, the SiO ₂ thin film 13 will be described in detail. The SiO ₂ thin film 13 is provided in order to prevent the ZnO thin film 14 from being affected by the deformation of the PAD electrode 12 due to heating and cooling during the high temperature treatment described above. Next, the thickness of the SiO ₂ thin film 13 including the relationship with the thickness of the ZnO thin film 14 will be described. Hereinafter, the thicknesses of the SiO ₂ thin film 13 and the ZnO thin film 14 are referred to as “film thickness”. The thermal expansion coefficient of each thin film is shown below. The thermal expansion coefficient (α1) of SiO ₂ forming the SiO ₂ thin film 13 is 0.55 × 10 ⁻⁶ / ° C. The thermal expansion coefficient (α3) of ZnO forming the ZnO thin film 14 is 4 × 10 ⁻⁶ / ° C. For reference, the thermal expansion coefficient (α2) of aluminum (Al) forming the PAD electrode 12 is 23.1 × 10 ⁻⁶ / ° C.

First, the relationship between the film thickness and the deformation amount due to thermal expansion and contraction (hereinafter referred to as “deformation amount”) will be described, and the setting of the film thicknesses of the SiO ₂ thin film 13 and the ZnO thin film 14 will be described.
The deformation amount of the ZnO thin film 14 and the deformation amount of the SiO ₂ thin film 13 are hZ × α3 × ΔT and hS × α1 × ΔT, respectively. In order to make the deformation amount of the ZnO thin film 14 smaller than the deformation amount of the SiO ₂ thin film 13, it is necessary to satisfy hZ × α3 × ΔT <hS × α1 × ΔT. For that purpose, hS> hZ × α3 / α1 (1). Substituting numerical values for α3 and α1 in equation (1) results in hS> hZ × α3 / α1≈7 (2).
The thickness of the ZnO thin film 14 is hZ, the thickness of the SiO ₂ thin film 13 is hS, the difference between the normal temperature and the heating temperature: ΔT, the thermal expansion coefficient of ZnO: α3, and the thermal expansion coefficient of SiO ₂ : α1.

From the formula (2), if the thickness of the SiO ₂ thin film 13 is about 7 times the thickness of the ZnO thin film 14, it has a sufficient effect to reduce the deformation amount of the ZnO thin film 14. You can see that For example, if the thickness (hZ) of the ZnO thin film 14 is 0.1 μm, the thickness (hS) of the SiO ₂ thin film 13 is desirably about 0.7 μm. However, even if the SiO ₂ thin film 13 is formed between the ZnO thin film 14 and the PAD electrode 12 by a numerical value smaller than the numerical value obtained by the above-described calculation formula, there is an effect of reducing the deformation amount. is doing. In the first embodiment, the thickness of the SiO ₂ thin film 13 is 1 μm and the thickness of the ZnO thin film 14 is 2 μm. However, problems such as cracking and peeling did not occur.

According to the manufacturing method of the thin film surface acoustic wave resonator element 10 of the first embodiment and the thin film surface acoustic wave resonator element 10 manufactured by the manufacturing method, the SiO ₂ thin film 13 includes the ZnO thin film 14, the PAD electrode 12, Is formed between. This makes it possible to prevent the ZnO thin film 14 from being affected by the deformation amount of the PAD electrode 12 due to heating, cooling, etc. during the high-temperature treatment described above. This will be described in detail below. PAD electrode 12, since the connection with the SiO ₂ thin film 13, SiO ₂ thin film 13 is influenced by the large amount of deformation of the PAD electrode 12. SiO ₂ forming the SiO ₂ thin film 13 is an amorphous film. As shown in the schematic diagram of the atomic arrangement in the amorphous thin film in FIG. 3, the amorphous thin film has a structure in which the atomic arrangement is disorderly arranged, so that the atoms 80 easily move to the gap 85, and therefore, the tenacious toughness. It has unique properties. Due to the tenacity of the amorphous thin film, the SiO ₂ thin film 13 is not broken even if a large amount of deformation occurs in the PAD electrode 12, and cracking, peeling, and the like do not occur.

The thermal expansion coefficient (α1) of the SiO ₂ thin film 13 is configured to be smaller than the thermal expansion coefficient (α2) of the PAD electrode 12. Since the ZnO thin film 14 is in contact with one surface of the SiO ₂ thin film 13, the ZnO thin film 14 is not affected by the large deformation amount of the PAD electrode 12, and is affected by the deformation amount of the SiO ₂ thin film 13 smaller than the deformation amount of the PAD electrode 12. It will be. Therefore, the ZnO thin film 14 is hardly cracked or peeled off. In other words, the provision of the SiO ₂ thin film 13 has a so-called relaxation effect that prevents the large deformation amount of the PAD electrode 12 from affecting the ZnO thin film 14. This relaxation effect can prevent cracking, peeling and the like of the ZnO thin film 14. In addition, it is possible to prevent occurrence of defects in the excitation electrode 16 due to the peeled ZnO thin film 14 contaminating the surface of the substrate 11 or the ZnO thin film 14.
(Second embodiment)

  As a second embodiment of the present invention, a thin film vibrator using a thin film vibrating piece will be described with reference to the drawings. FIG. 4 is a schematic front sectional view of the thin film vibrator as the second embodiment.

  As shown in FIG. 4, a thin film vibrator 30 of the present invention includes a thin film surface acoustic wave resonator element 10 as a thin film resonator element, a package 42 as a holder for storing the thin film surface acoustic wave resonator element 10, and a package. It is comprised from the cover body 41 which seals 42 opening parts. A connection electrode layer 44 is formed on the bottom surface of the recess of the package 42 made of ceramic or the like. The connection electrode layer 44 is provided with a gold layer (not shown) on the surface, and is joined to a bump 43 which is a connection portion of the thin film surface acoustic wave vibrating piece 10. Although not shown, the connection electrode layer 44 is also connected to an external terminal provided outside the package 42. A lid body 41 is fixed to the upper surface of the package 42 in which the thin film surface acoustic wave resonator element 10 is accommodated by using, for example, seam welding or metal heat fusion. With the lid 41, the opening of the package 42 is sealed.

In addition, since the thin film surface acoustic wave vibrating piece 10 used in the second embodiment has the same configuration as that described in the first embodiment, detailed description thereof is omitted in the second embodiment. In the thin film surface acoustic wave resonator element 10, a PAD electrode 32 as an electrode portion is formed on a substrate 31. Further, an amorphous thin film, for example, silicon oxide (on the upper surface of the wiring 31 extended from the PAD electrode 32 (not shown) or the other electrode is formed on the substrate 31 where the PAD electrode 32 is not formed. A SiO ₂ ) thin film (hereinafter referred to as “SiO ₂ thin film”) 33 is formed. On the SiO ₂ thin film 33, for example, a zinc oxide (ZnO) thin film (hereinafter referred to as “ZnO thin film”) 34 as a piezoelectric thin film is formed. On the upper surface of the ZnO thin film 34, an excitation electrode 36 for exciting a surface acoustic wave and a reflector 37 are formed. Further, the ZnO thin film 34 is provided with an opening 35. The opening 35 is formed so as to penetrate the portion of the ZnO thin film 34 and the SiO ₂ thin film 33 facing the PAD electrode 32. By forming the opening 35, the PAD electrode 32 is exposed on the upper surface of the thin film surface acoustic wave vibrating piece 10.

According to the thin film vibrator 30 shown in the second embodiment, the thin film surface acoustic wave resonator element 10 described in the first embodiment is housed. For this reason, even if the thin film vibrator 30 is processed at a high temperature, the ZnO thin film 34 is caused by a difference in deformation due to a difference in thermal expansion coefficient between the PAD electrode 32 and the ZnO thin film 34 of the thin film surface acoustic wave resonator element 10. It is possible to prevent cracking and peeling. Accordingly, it is possible to provide a thin film vibrator 30 having a so-called high stability in which there is no defect such as the excitation electrode 36 due to the cracking or peeling of the ZnO thin film 34 or there is little change in characteristics.
(Third embodiment)

  As a third embodiment of the present invention, a piezoelectric oscillator using a thin film vibrating piece will be described with reference to the drawings. FIG. 5 is a schematic front sectional view of a piezoelectric oscillator as a third embodiment.

  As shown in FIG. 5, the piezoelectric oscillator 50 of the present invention includes a thin film surface acoustic wave device 1000 as a thin film vibrating piece, a package 62 as a holder for housing the thin film surface acoustic wave device 1000, and an opening of the package 62. It is comprised from the cover body 61 which seals a part. A connection electrode layer 67 is formed on the bottom surface of the recess of the package 62 made of ceramic or the like. The connection electrode layer 67 is provided with a gold layer (not shown) on the surface, and is joined to a bump 63 which is a connection portion of the thin film surface acoustic wave device 1000. The connection electrode layer 67 is also connected to an external terminal provided outside the package 62 (not shown). A lid 61 is fixed to the upper surface of the package 62 in which the thin film surface acoustic wave device 1000 is accommodated, for example, using seam welding, metal heat fusion, or the like. With the lid 61, the opening of the package 62 is sealed.

In the thin film surface acoustic wave device 1000, for example, a PAD electrode 52 made of, for example, aluminum (Al), copper (Cu), or the like as an electrode portion is formed on a substrate 51 such as silicon (Si). Further, an amorphous thin film, for example, silicon oxide (on the upper surface of the PAD electrode 52 (not shown) or the upper surface of another electrode on the substrate 51 where the PAD electrode 52 is not formed. A SiO ₂ ) thin film (hereinafter referred to as “SiO ₂ thin film”) 53 is formed. On the SiO ₂ thin film 53, for example, a zinc oxide (ZnO) thin film (hereinafter referred to as “ZnO thin film”) 54 as a piezoelectric thin film is formed. On the upper surface of the ZnO thin film 54, an excitation electrode 56 and a reflector 57 for exciting the surface acoustic wave are formed. Further, the ZnO thin film 54 is provided with an opening 55. The opening 55 is formed so as to penetrate the ZnO thin film 54 and the SiO ₂ thin film 53 at a portion facing the PAD electrode 52. Since the opening 55 is formed, the PAD electrode 52 is exposed on the upper surface of the thin film surface acoustic wave device 1000.

  A circuit 64 having at least a function of exciting a surface acoustic wave is formed in a region close to the other surface of the substrate 51 where the PAD electrode 52 is provided or on the surface of the substrate (also referred to as a surface layer portion). The circuit 64 can be easily formed by using an ordinary monolithic semiconductor circuit manufacturing process technology or a hybrid circuit manufacturing process technology. The circuit 64 is connected to the bump 63, the PAD electrode 52, the excitation electrode 56, the reflector 57, and the like by connection wiring 65. Of the connection wiring 65, connection wiring to the excitation electrode 56 and the reflector 57 is not shown. The surfaces of the circuit 64 and the connection wiring 65 are covered with an insulating layer 66. The bump 63 is formed so as to be exposed on the insulating layer 66.

According to the piezoelectric oscillator 50 of the third embodiment described above, the SiO ₂ thin film 53 is formed between the ZnO thin film 54 and the PAD electrode 52 in the thin film surface acoustic wave device 1000 housed in the package 62. Yes. This makes it possible to prevent the ZnO thin film 54 from being affected by the deformation amount of the PAD electrode 52 due to thermal changes such as heating and cooling during the high-temperature treatment described above. Since this description is the same as that of the first embodiment, a description thereof will be omitted. Therefore, even if the piezoelectric oscillator 50 is processed at a high temperature, the ZnO thin film 54 is cracked due to the difference in deformation due to the difference in thermal expansion coefficient between the PAD electrode 52 and the ZnO thin film 54 of the thin film surface acoustic wave device 1000. It is possible to prevent peeling. Accordingly, it is possible to provide a piezoelectric oscillator 50 having a so-called high stability in which there is no defect such as the excitation electrode 56 due to the cracking or peeling of the ZnO thin film 54 or there is little change in characteristics.

  In the above-described third embodiment, the configuration in which the surface acoustic wave excitation portion and the circuit portion are provided in one substrate has been described. However, the surface acoustic wave excitation portion and the circuit portion are separately provided. It may be configured to be formed on the substrate and housed in a package.

The thin film surface acoustic wave vibration piece of 1st embodiment is shown, (a) is a top view, (b) is a front sectional view. The process flowchart which shows the manufacturing method of a thin film surface acoustic wave vibration piece. The schematic diagram of the atomic arrangement | sequence in an amorphous thin film. FIG. 6 is a schematic front sectional view of a thin film vibrator as a second embodiment. FIG. 6 is a schematic front sectional view of a piezoelectric oscillator as a third embodiment. FIG. 6 is a front sectional view showing a conventional thin film vibrating piece.

Explanation of symbols

10 ... thin film surface acoustic wave resonator element, 11, 31, 51 ... substrate, PAD electrode as 12, 32, 52 ... electrode portion, 13,33,53 ... SiO ₂ thin film as amorphous thin film, 14, 34, 54: ZnO thin film as a piezoelectric thin film, 15, 35, 55 ... opening, 16, 36, 56 ... excitation electrode, 16a, 16b ... comb electrode, 17, 37, 57 ... reflector, 17a, 17b ... reflection Electrode, 18a, 18b, 19a, 19b ... busbar, 20 ... aluminum thin film, 30 ... thin film vibrator, 41, 61 ... lid, 42, 62 ... package as cage, 43, 63 ... bump, 44, 67 ... Connection electrode layer, 64 ... circuit, 65 ... connection wiring, 66 ... insulating layer, 80 ... atoms, 85 ... gap, 1000 ... thin film surface acoustic wave device.

Claims (1)

An IC integrated thin film vibration in which an electrode part and a piezoelectric thin film having a thermal expansion coefficient different from the thermal expansion coefficient of the electrode part are formed on a substrate having a circuit part having a function of exciting at least surface acoustic waves A method of manufacturing a piece,
Forming the electrode part connected to the circuit part on the substrate;
Forming an amorphous thin film having a thermal expansion coefficient smaller than that of the electrode part on at least the surface of the electrode part;
Forming the piezoelectric thin film on the substrate including the surface of the amorphous thin film;
An annealing process for treating the piezoelectric thin film at 300 to 500 ° C .;
Forming an excitation electrode connected to the electrode portion on the surface of the piezoelectric thin film;
Removing the piezoelectric thin film and the amorphous thin film at a portion corresponding to the electrode part, and forming an opening for exposing the electrode part. Manufacturing method.

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