JP2016072808A - Duplexer and method of manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a duplexer capable of easily adjusting a fractional bandwidth of first and second band pass filters and also achieving miniaturization.SOLUTION: A duplexer 1 has a structure in which a low acoustic velocity film 5 and a piezoelectric film 6 are laminated on a high acoustic velocity film 4. An IDT electrode 7 for constituting a first band pass filter and an IDT electrode 8 for constituting a second band pass filter are formed on one surface of the piezoelectric film 6. A thickness of the piezoelectric film 6 on a portion where the first band pass filter is formed is different from a thickness of the piezoelectric film 6 on a portion where the second band pass filter is formed.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a duplexer having a structure in which a low sound velocity film and a high sound velocity material are laminated on a piezoelectric film, and a manufacturing method thereof.

  Conventionally, duplexers using surface acoustic wave elements have been widely used in mobile phones and the like. Patent Document 1 below discloses a surface acoustic wave device in which a plurality of surface acoustic wave elements are formed on the same piezoelectric substrate. The surface acoustic wave propagation direction in at least one surface acoustic wave element is different from the surface acoustic wave propagation directions of other surface acoustic wave elements. Thereby, the specific bandwidth is made different.

  Patent Document 2 below discloses a surface acoustic wave device in which a high sound velocity film, a low sound velocity film, and a piezoelectric film are laminated in this order on a support substrate. Patent Document 3 below discloses a surface acoustic wave device in which a plurality of surface acoustic wave elements are formed in the same piezoelectric substrate. In Patent Document 3, a dielectric layer is disposed between the piezoelectric substrate and the IDT electrode. The film thickness of the dielectric layer in at least one surface acoustic wave element is made different from the film thickness of the dielectric layers of other surface acoustic wave elements. Thereby, the specific bandwidth is changed.

WO13 / 061926 WO12 / 086639 JP 2012-169707 A

  In the surface acoustic wave device described in Patent Document 1, since a plurality of surface acoustic wave elements having different propagation directions of surface acoustic waves are formed, it is difficult to reduce the size. The surface acoustic wave device described in Patent Document 2 does not describe a configuration in which the specific bandwidth is different among a plurality of elastic elements.

  On the other hand, in patent document 3, it can adjust to the direction which makes a specific bandwidth small by changing the film thickness of a dielectric material layer. However, it cannot be adjusted in the direction of increasing the specific bandwidth. Therefore, the design range is limited and the Q value cannot be increased.

  An object of the present invention is to provide a duplexer that can easily adjust the specific bandwidth of the first and second band-pass filters and can be downsized.

  The present invention is a duplexer having a piezoelectric film, and is laminated on the high-sonic material, a high-sonic material having a bulk wave sound velocity propagating faster than the acoustic velocity of the elastic wave propagating through the piezoelectric film, A low acoustic velocity film having a lower bulk acoustic velocity than the bulk acoustic velocity propagating through the piezoelectric membrane, the piezoelectric film laminated on the low acoustic velocity film, and formed on one surface of the piezoelectric membrane, A first electrode constituting a first band-pass filter, and a second electrode formed on one surface of the piezoelectric film and constituting a second band-pass filter; A duplexer, wherein a thickness of the piezoelectric film in a portion where the first band-pass filter is configured is different from a thickness of the piezoelectric film in a portion where the second band-pass filter is configured. .

  In a specific aspect of the duplexer according to the present invention, the piezoelectric film in a portion where the first bandpass filter is configured, and the piezoelectric film in a portion which configures the second bandpass filter, Are connected. In this case, the piezoelectric film in the portion where the first and second band pass filters are formed can be formed by the same process.

  In another specific aspect of the duplexer according to the present invention, the piezoelectric film in a portion where the first band-pass filter is formed and the piezoelectric film in a portion which forms the second band-pass filter Are connected through a step.

  In still another specific aspect of the duplexer according to the present invention, at least one of the low-sonic film and the high-sonic material in a portion constituting the first band-pass filter is the second band-pass. It is different from the thickness of at least one of the low sound velocity film and the high sound velocity material in the portion constituting the mold filter.

  In another specific aspect of the duplexer according to the present invention, a support substrate is further provided, and the high sound velocity material is formed on the support substrate.

  In another specific aspect of the duplexer according to the present invention, the high sonic material is a single high sonic support substrate.

  A duplexer manufacturing method according to the present invention is a duplexer manufacturing method configured according to the present invention, comprising: a step of laminating a low-sonic film on a high-sonic material; and a piezoelectric film on the low-sonic film. A step of forming, a step of applying a resist on the piezoelectric film, a step of etching the piezoelectric film, removing the resist after the etching, and a relatively thick portion on the piezoelectric film, Providing a relatively thin portion, and forming the first and second electrodes on one surface of the piezoelectric film.

  In a specific aspect of the method for manufacturing a duplexer according to the present invention, prior to the formation of the piezoelectric film, at least one of the low-sonic film and the high-sonic material includes a portion in which the first band-pass filter is configured. The method further includes the step of making the thickness different from the portion where the second band-pass filter is formed.

  In another specific aspect of the method for manufacturing a duplexer according to the present invention, the method further includes a step of preparing a support substrate and a step of laminating the high sonic material on the support substrate.

  In another specific aspect of the method of manufacturing a duplexer according to the present invention, a high sonic support substrate is prepared as the high sonic material, and the low sonic film is laminated on the high sonic support substrate.

  According to the duplexer and the manufacturing method thereof according to the present invention, the laminated structure including the high sound velocity material and the low sound velocity film is used, and not only the miniaturization can be achieved, but also the first and second band pass filters can be realized. The specific bandwidth can be easily adjusted.

It is a typical front sectional view of the duplexer concerning a 1st embodiment of the present invention. It is a circuit diagram of a duplexer of a 1st embodiment of the present invention. It is a figure which shows the attenuation amount-frequency characteristic of the duplexer of the 1st Embodiment of this invention, and a comparative example. It is a figure which shows the impedance Smith chart of the antenna end of the duplexer of the 1st Embodiment of this invention and a comparative example. It is a figure which shows the impedance Smith chart of the receiving end of the duplexer of the 1st Embodiment of this invention and a comparative example. (A)-(d) is each typical sectional drawing for demonstrating 2nd Embodiment of the manufacturing method of the duplexer of this invention. It is typical sectional drawing for demonstrating 2nd Embodiment of the manufacturing method of the duplexer of this invention. (A)-(c) is each typical sectional drawing for demonstrating 3rd Embodiment of the manufacturing method of the duplexer of this invention. (A) And (b) is each typical sectional drawing for demonstrating 3rd Embodiment of the manufacturing method of the duplexer of this invention. (A) And (b) is each typical sectional drawing for demonstrating 3rd Embodiment of the manufacturing method of the duplexer of this invention. (A)-(c) is each typical sectional drawing for demonstrating 4th Embodiment of the manufacturing method of the duplexer of this invention. (A) And (b) is each typical sectional drawing for demonstrating 4th Embodiment of the manufacturing method of the duplexer of this invention. (A) And (b) is each typical sectional drawing for demonstrating 4th Embodiment of the manufacturing method of the duplexer of this invention. It is a typical front sectional view of the duplexer concerning the modification of a 1st embodiment.

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

  It should be pointed out that each embodiment described in this specification is an exemplification, and a partial replacement or combination of configurations is possible between different embodiments.

  FIG. 1 is a schematic front sectional view of a duplexer according to a first embodiment of the present invention, and FIG. 2 is a circuit diagram of the duplexer.

The duplexer 1 has a support substrate 2. On the support substrate 2, a low acoustic velocity film 3, a high acoustic velocity film 4, a low acoustic velocity film 5, and a piezoelectric film 6 are laminated in this order. The piezoelectric film 6 is made of LiTaO ₃ . However, the piezoelectric film 6 may be made of another piezoelectric single crystal such as LiNbO ₃ .

  The low sound velocity films 3 and 5 are made of an appropriate material whose bulk wave sound velocity is lower than that of the bulk wave propagating through the piezoelectric film 6. In the present embodiment, the low acoustic velocity films 3 and 5 are made of silicon oxide.

  The material constituting the low acoustic velocity films 3 and 5 is not limited to silicon oxide, and glass, silicon oxynitride, tantalum oxide, a compound obtained by adding fluorine, carbon, or boron to silicon oxide, or the like can be used.

  The high acoustic velocity film 4 is made of an appropriate material whose propagating bulk wave acoustic velocity is higher than the acoustic velocity of elastic waves propagating through the piezoelectric film 6. In the present embodiment, the high acoustic velocity film 4 is made of silicon nitride. However, the high sound velocity film 4 is made of silicon nitride, aluminum nitride, aluminum oxide, silicon carbide, silicon oxynitride, DLC film, diamond, or an appropriate material mainly composed of these materials. Also good.

  The high acoustic velocity film 4 is laminated on the surface of the low acoustic velocity film 5 opposite to the piezoelectric film 6. Therefore, elastic waves are less likely to leak below the high sound velocity film 4. Thereby, the Q value is increased.

  IDT electrodes 7 and 8 are formed on the piezoelectric film 6. The duplexer 1 includes a transmission filter 11 as a first band-pass filter and a reception filter 12 as a second band-pass filter. The transmission filter 11 and the reception filter 12 have a plurality of elastic wave resonators. In FIG. 1, an IDT electrode 7 of one acoustic wave resonator constituting the transmission filter 11 is illustrated as the first electrode. Similarly, the IDT electrode 8 of one of the acoustic wave resonators constituting the reception filter 12 is illustrated as the second electrode.

  The feature of the present embodiment is that in the structure in which the low sound velocity film 5 and the high sound velocity film 4 are laminated below the piezoelectric film 6, the thickness of the piezoelectric film 6 differs between the transmission filter 11 and the reception filter 12. There is to be. More specifically, the thickness of the piezoelectric film 6 in the portion where the transmission filter 11 is configured is thicker than the thickness of the piezoelectric film 6 in the portion where the reception filter 12 is configured.

  Accordingly, in the portion where the transmission filter 11 is configured, the upper surface 6 a of the piezoelectric film 6 is located higher than the upper surface 6 b of the piezoelectric film 6 in the portion configuring the reception filter 12. The upper surface 6a and the upper surface 6b are connected via the level | step difference 6c.

  The step 6c is inclined so that the height gradually decreases from the upper surface 6a to the upper surface 6b. That is, the step 6c is formed by the inclined surface. But the level | step difference 6c may be formed of the surface extended in the direction orthogonal to upper surface 6a, 6b.

  In the duplexer 1, the thickness of the piezoelectric film 6 in the portion where the transmission filter 11 is configured is thicker than the thickness of the piezoelectric film 6 in the portion where the reception filter 12 is configured. The width and the specific bandwidth of the reception filter 12 can be made different. Therefore, it has a laminated structure in which the high sound velocity film 4, the low sound velocity film 5, and the piezoelectric film 6 are laminated, and not only can the size be reduced, but also the relative bandwidth of the transmission filter 11 and the reception filter 12 can be easily adjusted. Is possible.

  The circuit configuration of the duplexer 1 will be described with reference to FIG.

  The duplexer 1 has an antenna terminal 14 connected to the antenna 13. An inductor L1 is connected between the antenna terminal 14 and the ground potential. A transmission filter 11 and a reception filter 12 are connected to the antenna terminal 14. More specifically, the transmission filter 11 is connected between the antenna terminal 14 and the transmission terminal 15. A reception filter 12 is connected between the antenna terminal 14 and the reception terminal 16.

  The transmission filter 11 includes series arm resonators S1 to S5 and parallel arm resonators P1 to P4. That is, in the series arm connecting the transmission terminal 15 and the antenna terminal 14, the series arm resonators S1 to S5 are connected to each other in series. An inductor L2 is connected between the series arm resonator S1 and the transmission terminal 15. The parallel arm resonator P1 is connected between a connection point between the series arm resonators S1 and S2 and the ground potential. One end of the parallel arm resonator P2 is connected to a connection point between the series arm resonators S2 and S3. One end of the parallel arm resonator P3 is connected to a connection point between the series arm resonators S3 and S4. One end of the parallel arm resonator P4 is connected to a connection point between the series arm resonators S4 and S5. The other ends of the parallel arm resonators P2 to P4 are connected in common and connected to the ground potential via the inductor L3.

  The transmission filter 11 is a ladder-type elastic wave filter having the series arm resonators S1 to S5 and the parallel arm resonators P1 to P4.

  The reception filter 12 includes a 5IDT type longitudinally coupled resonator type elastic wave filter 17. Elastic wave resonators 18 and 19 are connected between the longitudinally coupled resonator type acoustic wave filter 17 and the antenna terminal 14. An elastic wave resonator 20 is connected between a connection point between the elastic wave resonators 18 and 19 and a ground potential. An elastic wave resonator 21 is connected between the output terminal of the longitudinally coupled resonator type elastic wave filter 17 and the ground potential.

  Next, based on a specific experimental example, it will be described that according to the above embodiment, the specific bandwidth of the transmission filter 11 and the reception filter 12 can be easily adjusted and impedance matching can be satisfactorily performed.

  Based on the following design parameters, a Band4 duplexer was fabricated as the duplexer 1 of the above embodiment. The transmission frequency band of Band4 is 1710 to 1755 MHz, and the reception frequency band is 2101 to 2155 MHz. In Band 4, the frequency difference between the transmission band and the reception band is wide. That is, the center frequency of the transmission band is 1732.5 MHz, and the center frequency of the reception band is separated from 2132.5 MHz.

Laminated structure in transmission filter 11: LiTaO ₃ film (thickness 600 nm) / SiO ₂ film (thickness 570 nm) / SiN film (thickness 1800 nm) / SiO ₂ film (thickness 2000 nm) / Si substrate Laminated structure in reception filter 12: LiTaO ₃ film (Thickness 490 nm) / SiO ₂ film (thickness 570 nm) / SiN film (thickness 1800 nm) / SiO ₂ film (thickness 2000 nm) / Si substrate

  For comparison, a duplexer of a comparative example was manufactured in the same manner as in the above embodiment, except that the laminated structure in the reception filter was the same as that of the transmission filter.

  FIG. 3 shows the attenuation-frequency characteristics of the duplexers of the above embodiment and the comparative example. FIG. 4 shows an impedance Smith chart at the antenna end of the duplexer of the embodiment and the comparative example, and FIG. 5 shows an impedance Smith chart at the receiving end. 3 to 5, the solid line indicates the result of the embodiment, and the broken line indicates the result of the comparative example.

  The design parameters of the transmission filter and the reception filter are as shown in Tables 1 to 3 below.

  Table 1 shows design parameters of the serial arm resonators S1 to S5 and the parallel arm resonators P1 to P4 of the transmission filter.

  Table 2 shows design parameters of the 5IDT type longitudinally coupled resonator type elastic wave filter 17. The first to fifth IDTs are first to fifth IDTs arranged in order along the surface acoustic wave propagation direction.

  Table 3 below shows design parameters of the acoustic wave resonators 18 to 21 used in the reception filter.

  As can be seen from FIG. 3, in the comparative example, the waveform is broken in the pass band of the reception filter. Further, as apparent from FIG. 4, in the impedance Smith chart at the antenna end, the portion surrounded by the broken line swells, and it can be seen that the impedance matching is shifted.

  In Band4, as described above, since the center frequency of the transmission band and the center frequency of the reception band are separated, the electrode finger pitch of the IDT electrode in the transmission filter and the electrode finger pitch of the IDT electrode in the reception filter This is probably because of That is, since the electrode finger pitch is greatly different, there is a difference between the specific bandwidth of the transmission filter and the specific bandwidth of the reception filter. Further, in the structure in which the high acoustic velocity film 4 and the low acoustic velocity film 5 are laminated, the specific bandwidth is determined by the normalized film thickness H / λ of the laminated structure. The width is reduced, making impedance matching difficult.

On the other hand, as can be seen from FIG. 3, in the above embodiment, it can be seen that the waveform does not collapse in the pass band of the reception filter. This is because the thickness of the laminated structure in the reception filter is set as described above, that is, the thickness of the piezoelectric film 6 made of LiTaO ₃ is changed to 490 nm. Since the center frequency of the transmission filter is 0.81 times the center frequency of the reception filter, the LiTaO ₃ film thickness is 600 nm × 0.81 = 490 nm. Therefore, it can be considered that the specific bandwidth of the reception filter can be designed to be equivalent to that of the transmission filter, thereby improving the characteristics of the reception filter.

  Further, as is apparent from FIGS. 4 and 5, in the embodiment, it can be seen that the impedance matching at the antenna end and the receiving end is also good.

In this experimental example, the standardized film thickness of LiTaO ₃ was designed to be the same for the transmission filter and the reception filter. That is, although the actual film thickness of the piezoelectric film 6 was varied, the normalized film thicknesses of the piezoelectric film part in the transmission filter and the piezoelectric film part in the reception filter were designed to be the same.

  However, in the present invention, not only the thickness of the piezoelectric film but also the thicknesses of the low sound velocity film and the high sound velocity film may be made different between the transmission filter and the reception filter. That is, at least one of the low sound speed film and the high sound speed film in the part constituting the first band pass filter is used, and the low sound speed film and the high sound speed film in the part constituting the second band pass filter are used. The thickness may be different from at least one of the thicknesses. Thereby, adjustment of temperature characteristics and suppression of harmonics can be realized.

  In the above embodiment, the low sound velocity film 3 is further laminated below the high sound velocity film 4, but the lower sound velocity film 3 may be omitted.

  Here, an example of the manufacturing method of the duplexer 1 of the said embodiment is demonstrated. A low sonic film 3, a high sonic film 4, and a low sonic film 5 are formed on the support substrate 2 by a film forming method such as sputtering. Next, after the piezoelectric film 6 is formed, an area mask is arranged in the region where the transmission filter is configured, and milling is performed by irradiating the piezoelectric film 6 with a laser beam on the region where the reception filter is configured To do. In this way, the thickness of the piezoelectric film 6 can be reduced on the side where the reception filter is configured. That is, it is possible to obtain the piezoelectric film 6 in which the upper surface 6a and the upper surface 6b of FIG. 1 are connected via the step 6c. Finally, IDT electrodes 7 and 8 are formed by a photolithography method or the like. In this way, the duplexer 1 can be obtained.

  Next, a second embodiment of the duplexer manufacturing method of the present invention will be described with reference to FIGS.

As shown in FIG. 6A, a low acoustic velocity film 3 made of SiO _{2 is} formed on a support substrate 2 made of Si by a thin film forming method such as sputtering. Next, as shown in FIG. 6B, a high-velocity film 4 made of SiN is formed by a thin film forming method such as sputtering.

Further, as shown in FIG. 6C, a SiO ₂ film 5a is formed on the high sound velocity film 4. On the other hand, a piezoelectric film 6 made of LiTaO ₃ having a SiO ₂ film 5b laminated on one side is prepared. The piezoelectric film 6 is laminated on the SiO ₂ film 5a from the SiO ₂ film 5b side. In this way, the laminate shown in FIG. 6 (d) is obtained.

  Thereafter, the piezoelectric film 6 is polished, and a mask M is disposed on the portion where the transmission filter is formed as shown in FIG. Next, the laser beam is irradiated as indicated by an arrow to mill the piezoelectric film 6 in the portion where the reception filter is formed. Thereby, an upper surface 6b and a step 6c which are lower than the upper surface 6a are formed. Thereafter, the IDT electrodes 7 and 8 shown in FIG. 1 are formed by photolithography. In this way, the piezoelectric film 6 having portions with different thicknesses can be formed.

FIGS. 8A to 8C, FIGS. 9A and 9B, and FIGS. 10A and 10B are diagrams for explaining the third embodiment of the duplexer manufacturing method of the present invention. It is typical sectional drawing. As shown in FIG. 8A, a low acoustic velocity film 3 made of SiO _{2 is} formed on the support substrate 2 by sputtering or the like. Next, as shown in FIG. 8B, a high sonic film 4 made of SiN is formed on the low sonic film 3 made of SiO ₂ . Further, a resist layer 22 is formed in a region where the transmission filter is configured.

  Next, as shown by an arrow in FIG. 8C, etching is performed so that the thickness of the high-velocity film 4 is reduced in the portion where the reception filter is formed. Thereafter, the resist layer 22 is removed.

Next, a low sonic film 5 made of SiO _{2 is} formed on the high sonic film 4 by sputtering or the like. As shown in FIG. 9A, the thickness of the high acoustic velocity film 4 as a base is reduced on the receiving filter side. Therefore, a step is formed on the surface of the low acoustic velocity film 5 made of SiO ₂ . Next, the upper surface of the low acoustic velocity film 5 is flattened by CMP polishing or the like. Thereafter, as shown in FIG. 9B, a piezoelectric film 6 made of LiTaO ₃ having a SiO ₂ film 5c laminated on one side is laminated on the low sound velocity film 5 from the SiO ₂ film 5c side. Thereby, the laminated body shown to Fig.10 (a) is obtained.

  Next, as shown in FIG. 10B, as in the case of the second embodiment, the area mask 24 is arranged on the portion where the transmission filter is configured. In this state, a laser beam is irradiated to mill the piezoelectric film 6. In this way, a structure in which the upper surface 6a and the upper surface 6b at a position lower than the upper surface 6a are connected via the step 6c is obtained.

  Since the process as described above is performed, the thickness of the low sound velocity film 5 in the transmission filter is made thinner than the thickness of the low sound velocity film 5 in the reception filter. Thereby, the temperature characteristic can be adjusted.

  On the other hand, in the film thickness of the high sound speed film, the film thickness of the high sound speed film in the transmission filter is thicker than the film thickness of the high sound speed film in the reception filter. However, the difference in the film thickness of the high sound velocity film does not affect the difference in the film thickness of the low sound velocity film 5.

  A fourth embodiment of the duplexer manufacturing method of the present invention will be described with reference to FIGS. 11 (a) to 11 (c) to 13 (a) and 13 (b).

First, as shown in FIG. 11A, an SiO ₂ film 5d is formed on the piezoelectric film 6. Thereafter, as shown in FIG. 11A, the resist layer 25 is placed on the side where the reception filter is formed on the SiO ₂ film 5d, and etching is performed as indicated by an arrow. Thereby, the thickness of the portion of the SiO ₂ film 5d that is not covered with the resist layer 25 can be made relatively thin. Next, the resist layer 25 is removed, and a high sound velocity film 4 made of SiN is formed by sputtering or the like as shown in FIG.

Further, as shown in FIG. 11C, an SiO ₂ film 3a is formed on the high sound velocity film 4 made of SiN. In both the high sound velocity film 4 and the SiO ₂ film 3a, the upper surface is lower on the side where the transmission filter is configured than on the side where the reception filter is configured.

Next, as shown in FIG. 12A, the upper surface of the SiO ₂ film 3a is planarized by CMP polishing.

On the other hand, as shown in FIG. 12B, a SiO ₂ film 3b is formed on the support substrate 2. Next, as shown in FIG. 13A, the laminate shown in FIG. 12A is bonded onto the support substrate 2 so that the SiO ₂ film 3a contacts the SiO ₂ film 3b. This joining can be performed by heat treatment or the like. Thereafter, as shown in FIG. 13B, the area mask 24 is disposed on the area where the transmission filter is formed, and the piezoelectric film 6 is milled as indicated by an arrow. In this way, the piezoelectric film 6 in which the upper surface 6a and the upper surface 6b are connected via the step 6c can be formed.

  In the third and fourth embodiments, after the piezoelectric film 6 is processed as described above, an IDT electrode may be formed by a well-known photolithography method.

  As in the modification shown in FIG. 14, the low sound velocity film 5 and the piezoelectric film 6 may be laminated on the support substrate 31 made of a high sound velocity material. As such a high sound speed material, an appropriate high sound speed material such as the material constituting the high sound speed film 4 described above may be used.

  In the above embodiment, the transmission filter 11 is a ladder type filter and the reception filter 12 has the longitudinally coupled resonator type elastic wave filter 17. However, the first and second band pass in the duplexer of the present invention are described. The circuit configuration of the mold filter is not particularly limited. That is, the first and second band-pass filters can be configured by various conventionally known elastic wave filters.

1 ... duplexer 2 ... supporting substrate 3,5 ... low acoustic velocity film 3a, 3b, 5a~5d ... SiO ₂ film 4 ... high acoustic velocity film 6 ... piezoelectric film 6a, 6b ... top 6c ... step 7, 8 ... IDT electrodes 11 ... Transmission filter 12 ... Reception filter 13 ... Antenna 14 ... Antenna terminal 15 ... Transmission terminal 16 ... Reception terminal 17 ... Vertical coupled resonator type elastic wave filters 18-21 ... Acoustic wave resonator 22 ... Resist layer 24 ... Area mask 25 ... Resist Layer 31 ... support substrate L1-L3 ... inductor M ... mask P1-P4 ... parallel arm resonator S1-S5 ... series arm resonator

Claims (10)

A duplexer having a piezoelectric film,
A high sound velocity material having a bulk wave sound velocity propagating higher than the sound velocity of the elastic wave propagating through the piezoelectric film;
A low-velocity film laminated on the high-velocity material, and having a bulk wave sound velocity propagating lower than a bulk wave sound velocity propagating through the piezoelectric film;
The piezoelectric film laminated on the low sound velocity film;
A first electrode formed on one surface of the piezoelectric film and constituting a first band-pass filter;
A second electrode that is formed on one surface of the piezoelectric film and forms a second bandpass filter;
The duplexer, wherein a thickness of the piezoelectric film in a portion where the first band-pass filter is configured is different from a thickness of the piezoelectric film in a portion where the second band-pass filter is configured.   2. The duplexer according to claim 1, wherein the piezoelectric film in a portion in which the first band-pass filter is configured and the piezoelectric film in a portion in which the second band-pass filter is configured are continuous. .   The piezoelectric film in a portion where the first band-pass filter is formed and the piezoelectric film in a portion which forms the second band-pass filter are connected via a step. The duplexer described.   At least one of the low sound velocity film and the high sound velocity material in the portion constituting the first band pass filter is the low sound velocity membrane in the portion constituting the second band pass filter and The duplexer according to any one of claims 1 to 3, wherein the duplexer is different from a thickness of at least one of the high sound velocity materials.   The duplexer according to claim 1, further comprising a support substrate, wherein the high sound velocity material is formed on the support substrate.   The duplexer according to claim 1, wherein the high sound velocity material is a single high sound velocity support substrate. It is a manufacturing method of the duplexer of any one of Claims 1-6,
A process of laminating a low-sonic film on a high-sonic material;
Forming a piezoelectric film on the low sound velocity film;
Applying a resist on the piezoelectric film;
Etching the piezoelectric film;
Removing the resist after the etching and providing the piezoelectric film with a relatively thick portion and a relatively thin portion;
Forming a first electrode and a second electrode on one surface of the piezoelectric film.   Prior to the formation of the piezoelectric film, in at least one of the low sound velocity film and the high sound velocity material, a portion in which the first band-pass filter is formed and a portion in which the second band-pass filter is formed The method for manufacturing a duplexer according to claim 7, further comprising a step of varying the thickness. Preparing a support substrate;
The duplexer manufacturing method according to claim 7, further comprising a step of laminating the high acoustic velocity material on the support substrate.   The duplexer manufacturing method according to any one of claims 7 to 9, wherein a high sonic support substrate is prepared as the high sonic material, and the low sonic film is laminated on the high sonic support substrate.

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