JP6701725B2 - Method of manufacturing acoustic wave device - Google Patents

Description

  The present invention relates to a method of manufacturing an elastic wave device and an elastic wave device.

  Conventionally, elastic wave devices have been widely used in mobile phones and the like. Patent Document 1 discloses an example of an elastic wave device. This acoustic wave device is a duplexer having a transmission filter and a reception filter formed on the same piezoelectric substrate. The pass band of the transmission filter is composed of a ladder type filter. The pass band of the reception filter is composed of a plurality of longitudinally coupled resonator type elastic wave filters.

  Further, Patent Document 2 discloses, as an example of an elastic wave device, a ladder type filter in which the duty of a parallel arm resonator is larger than the duty of a series arm resonator. In the ladder type filter, it is described that the frequency band is adjusted by changing the film thickness of the insulating film formed so as to cover the IDT electrode.

JP, 2013-081068, A JP, 2002-217679, A

  In the acoustic wave device as disclosed in Patent Document 1, in order to avoid cost increase, it is required to perform frequency adjustment more simply by collectively performing exposure film formation. However, when the transmission band and the reception filter formed on one chip are largely different in pass band, the frequency dependence of the line width of the electrode finger of the IDT electrode in the transmission filter and the reception filter is different. Even if the frequency adjustment method is applied to simultaneously adjust the line widths of the IDT electrodes of both filters, the frequency intervals of both filters are changed, so that the frequency cannot be easily adjusted.

  An object of the present invention is to provide a method for manufacturing an acoustic wave device and an acoustic wave device that can easily adjust the frequency.

  A method of manufacturing an acoustic wave device according to the present invention includes a step of preparing a piezoelectric substrate, a step of forming a metal film on the piezoelectric substrate, and a step of patterning the metal film by photolithography to form a plurality of IDT electrodes. And a step of forming a plurality of elastic wave element portions having different frequencies, wherein the plurality of elastic wave element portions are formed by collectively performing exposure in a photolithography method, and the plurality of elastic wave element portions are formed. The duty of the IDT electrodes in the plurality of acoustic wave element portions is adjusted so that the frequency dependence of the line widths of the electrode fingers of the IDT electrodes in each portion is uniform.

  In a particular aspect of the method for manufacturing an elastic wave device according to the present invention, the IDT electrode in at least one elastic wave element part having a different frequency from other elastic wave element parts among the plurality of elastic wave element parts. Of the IDT electrode in the other acoustic wave element section is made different. In this case, the frequencies in the pass bands of the plurality of elastic wave element portions can be easily adjusted.

  In another specific aspect of the method for manufacturing an elastic wave device according to the present invention, the plurality of elastic wave element sections are a plurality of elastic wave filter sections, and another elastic wave filter among the plurality of elastic wave filter sections. The duty of the IDT electrode in at least one elastic wave filter portion having a pass band different from that of the other portion is different from the duty of the IDT electrode in the other acoustic wave filter portions. In this case, the frequencies in the passbands of the plurality of elastic wave filter units can be easily adjusted.

  In another specific aspect of the method for manufacturing an elastic wave device according to the present invention, the IDT electrode having a frequency at an end of each pass band in at least two elastic wave filter parts of the plurality of elastic wave filter parts. Align the dependence on the electrode finger line width. In this case, the frequency intervals of the passbands are unlikely to shift.

  In still another specific aspect of the method for manufacturing an elastic wave device according to the present invention, two elastic wave filter parts having different pass bands and a minimum difference between the pass bands among the plurality of elastic wave filter parts. In, the frequency of the end portion of the low-pass side of the pass band in the elastic wave filter portion where the pass band is located on the high band side, and the high band of the pass band in the elastic wave filter portion where the pass band is located on the low band side. The dependence of the frequency of the side end on the line width of the electrode finger of the IDT electrode is made uniform. In this case, it is even more difficult for the frequency intervals of the passbands to differ from each other.

  In another specific aspect of the method for manufacturing an elastic wave device according to the present invention, a multiplexer is formed in which the plurality of elastic wave filter units are commonly connected.

  In still another specific aspect of the method for manufacturing an elastic wave device according to the present invention, the plurality of elastic wave element portions are a plurality of elastic wave resonator portions, and among the plurality of elastic wave resonator portions, another A duty of the IDT electrode in at least one elastic wave resonator portion having a resonance frequency different from that of the elastic wave resonator portion is made different from a duty of the IDT electrode in another elastic wave resonator portion.

  An elastic wave device according to the present invention includes a piezoelectric substrate, and a plurality of elastic wave element portions that are formed on the piezoelectric substrate and each have an IDT electrode and have different frequencies. The duty of the IDT electrode is adjusted.

  In a particular aspect of the elastic wave device according to the present invention, among the plurality of elastic wave element parts, the duty of the IDT electrode in at least one elastic wave element part having a frequency different from that of other elastic wave element parts is , Different from the duty of the IDT electrode in the other acoustic wave device section. In this case, the frequencies in the pass bands of the plurality of elastic wave element portions can be easily adjusted.

  In another specific aspect of the elastic wave device according to the present invention, the plurality of elastic wave element sections are a plurality of elastic wave filter sections, and among the plurality of elastic wave filter sections, other elastic wave filter sections are provided. The duty of the IDT electrode in at least one elastic wave filter unit having a different pass band is different from the duty of the IDT electrode in the other elastic wave filter units. In this case, the frequencies in the passbands of the plurality of elastic wave filter units can be easily adjusted.

  In another specific aspect of the acoustic wave device according to the present invention, an electrode finger of the IDT electrode having a frequency at an end of each pass band in at least two acoustic wave filter units among the plurality of acoustic wave filter units. Depends on the line width of. In this case, the frequency intervals of the passbands are unlikely to shift.

  In still another specific aspect of the elastic wave device according to the present invention, among the plurality of elastic wave filter parts, two elastic wave filter parts having different pass bands and a minimum difference between the pass bands are passed. The frequency of the low-frequency side end of the pass band in the elastic wave filter unit whose band is located on the high band side, and the high band side end of the pass band in the elastic wave filter unit whose pass band is located on the low band side. The dependence of the frequency of the part on the line width of the electrode finger of the IDT electrode is uniform. In this case, it is even more difficult for the frequency intervals of the passbands to differ from each other.

  In another specific aspect of the elastic wave device according to the present invention, a multiplexer is formed in which the plurality of elastic wave filter units are commonly connected.

  In still another specific aspect of the elastic wave device according to the present invention, the plurality of elastic wave element units are a plurality of elastic wave resonator units, and another elastic wave resonance unit of the plurality of elastic wave resonator units is used. The duty of the IDT electrode in at least one elastic wave resonator portion having a resonance frequency different from that of the child portion is different from the duty of the IDT electrodes in the other acoustic wave resonator portions. In this case, the frequency of each elastic wave resonator section can be easily adjusted.

  ADVANTAGE OF THE INVENTION According to this invention, the manufacturing method of an elastic wave apparatus and the elastic wave apparatus which can adjust frequency easily can be provided.

It is a circuit diagram of the elastic wave device which concerns on the 1st Embodiment of this invention. It is a schematic plan view which shows the electrode structure of the series arm resonator connected to the input terminal in the 1st Embodiment of this invention. FIG. 3 is a schematic plan view showing an electrode configuration of first and second longitudinally coupled resonator type elastic wave filters according to the first embodiment of the present invention. (A)-(d) is a typical front sectional view for explaining the manufacturing method of the elastic wave device concerning a 1st embodiment of the present invention. The frequency with respect to the line width of the electrode finger of each IDT electrode in the first band pass filter when the duty of each IDT electrode of the first band pass filter in the first embodiment of the present invention is set to 0.55. It is a figure which shows the dependency of. The frequency with respect to the line width of the electrode finger of each IDT electrode in the second band pass filter when the duty of each IDT electrode of the second band pass filter in the first embodiment of the present invention is set to 0.65. It is a figure which shows the dependency of. It is a figure which shows the relationship of the frequency dependence with respect to the line width of the electrode finger of each IDT electrode in the 1st, 2nd band pass filter of the 1st Embodiment of this invention, and the duty of each IDT electrode. .. It is a schematic diagram of the multiplexer which concerns on the 2nd Embodiment of this invention. It is a circuit diagram of an elastic wave device according to a third embodiment of the present invention.

  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 the present specification is an exemplification, and a partial replacement or combination of the configurations is possible between different embodiments.

  FIG. 1 is a circuit diagram of an elastic wave device according to a first embodiment of the present invention.

  The elastic wave device according to the present embodiment is the duplexer 1 shown in FIG. The duplexer 1 has a first band-pass filter 2a as a plurality of elastic wave filter units and a second band-pass filter 2b having a different pass band from the first band-pass filter 2a. The duplexer 1 has an antenna terminal 4 connected to the antenna. The first and second band pass filters 2a and 2b are commonly connected to the antenna terminal 4.

The first and second band pass filters 2a and 2b are formed on the same piezoelectric substrate. In this embodiment, the piezoelectric substrate is made of LiTaO ₃ . The piezoelectric substrate may be made of a piezoelectric single crystal such as LINbO ₃ or an appropriate piezoelectric ceramic.

  The duplexer 1 is a duplexer whose pass band is located at Band4. More specifically, the first band-pass filter 2a is a transmission filter having a pass band of 1710 MHz or more and 1755 MHz or less. The second bandpass filter 2b is a reception filter having a passband of 2110 MHz or more and 2155 MHz or less.

  The first band pass filter 2a is a ladder filter having a plurality of elastic wave resonators. More specifically, the first bandpass filter 2 a has an input terminal 3. The first band pass filter 2a includes series arm resonators S1a, S1b, S2a, S2b, S3a, S3b, S4, S5a to S5c connected in series between the input terminal 3 and the antenna terminal 4. Have. Further, the first band pass filter 2a also has parallel arm resonators P1a, P1b, P2a, P2b, P3, P4a, P4b.

  The series arm resonators S1a, S1b, S2a, S2b, S3a, S3b, S4, S5a to S5c and the parallel arm resonators P1a, P1b, P2a, P2b, P3, P4a, P4b as the elastic wave resonators are respectively It has an IDT electrode. The duty of each IDT electrode is 0.5. The details of the first band-pass filter 2a will be described later.

  The second bandpass filter 2 b has an output terminal 5. The second band pass filter 2b has first and second longitudinally coupled resonator type elastic wave filters 6a and 6b connected in parallel with each other between the antenna terminal 4 and the output terminal 5. The first and second longitudinally coupled resonator type elastic wave filters 6a and 6b are 3IDT type longitudinally coupled resonator type elastic wave filters, respectively. The duty of each IDT electrode of the first and second longitudinally coupled resonator type elastic wave filters 6a and 6b is set to 0.651. As described above, the duty of each IDT electrode of the second band pass filter 2b is different from the duty of each IDT electrode of the first band pass filter 2a. The details of the second band-pass filter 2b will be described later.

  The feature of this embodiment is that the first and second band-pass filters 2a and 2b have the same frequency dependence with respect to the line width of the electrode finger of each IDT electrode. This is because the duty of each IDT electrode of 2a and 2b is different. This makes it possible to easily adjust the frequencies in the pass bands of the first and second band pass filters 2a and 2b. This will be described below together with the details of the configuration of the duplexer 1 and the manufacturing method.

  As shown in FIG. 1, in the first bandpass filter 2a, the parallel arm resonators P1a and P1b are provided between the connection point between the series arm resonator S1b and the series arm resonator S2a and the ground potential. Are connected in series with each other. Parallel arm resonators P2a and P2b are connected in series with each other between a connection point between the series arm resonator S2b and the series arm resonator S3a and the ground potential. The parallel arm resonator P3 is connected between the connection point between the series arm resonator S3b and the series arm resonator S4 and the ground potential. Parallel arm resonators P4a and P4b are connected in series with each other between the ground potential and the connection point between the series arm resonator S4 and the series arm resonator S5a.

  The parallel arm resonators P1b, P2b, P3 and P4b are commonly connected to the ground potential. The first inductor L1 is connected in parallel with the series arm resonators S1a and S1b. One end of the first inductor L1 is connected to the input terminal 3. The other end of the first inductor L1 is connected to the end of the series arm resonator S1b on the series arm resonator S2a side. The inductance of the first inductor L1 is 2.6 nH. The circuit configuration of the first bandpass filter 2a is not particularly limited.

  In the second band-pass filter 2b, between the first and second longitudinally coupled resonator type elastic wave filters 6a, 6b and the antenna terminal 4, elastic wave resonators S11a to S11c for characteristic adjustment are mutually provided. It is connected in series. Between the connection point 6x1 between the first and second longitudinally coupled resonator type elastic wave filters 6a and 6b and the output terminal 5 and the ground potential, the elastic wave resonators P11a and P11b for characteristic adjustment are also provided. They are connected in series with each other. The second inductor L2 is connected between the connection point 6x2 between the first and second longitudinally coupled resonator type elastic wave filters 6a and 6b and the output terminal 5 and the ground potential. A capacitance C is connected between the output terminal 5 and the first and second longitudinally coupled resonator type elastic wave filters 6a and 6b, the elastic wave resonator P11a and the second inductor L2. The inductance of the second inductor L2 is 4.7 nH, and the capacitance of the capacitance C is 100 pF. The circuit configuration of the second bandpass filter 2b is not particularly limited.

  On the other hand, a third inductor L3 for impedance adjustment is connected between the antenna terminal 4 and the ground potential. The inductance of the third inductor L3 is 2.2 nH. Note that the third inductor L3 may not be provided.

  Specifically, each acoustic wave resonator in the first embodiment has a configuration shown in FIG. 2 below. Note that FIG. 2 shows the configuration of the series arm resonator S1a as a representative.

  FIG. 2 is a schematic plan view showing an electrode configuration of the series arm resonator connected to the input terminal in the first embodiment.

  The series arm resonator S1a has an IDT electrode 8aA provided on a piezoelectric substrate. Reflectors 10A are provided on both sides of the IDT electrode 8aA in the elastic wave propagation direction. The series arm resonators S1b, S2a, S2b, S3a, S3b, S4, S5a to S5c and the parallel arm resonators P1a, P1b, P2a, P2b, P3, P4a, P4b shown in FIG. 1 are the same as the series arm resonator S1a. It has a similar configuration. The elastic wave resonators S11a to S11c, P11a, P11b also have the same configuration as the series arm resonator S1a.

  On the other hand, the first and second longitudinally coupled resonator type elastic wave filters 6a and 6b have the configuration shown in FIG. 3 below.

  FIG. 3 is a schematic plan view showing an electrode configuration of the first and second longitudinally coupled resonator type elastic wave filters according to the first embodiment.

  The first longitudinally coupled resonator type elastic wave filter 6a has IDT electrodes 8bA1 to 8bA3. Reflectors 10Ba are provided on both sides of the IDT electrodes 8bA1 to 8bA3 in the elastic wave propagation direction. Similarly, the second longitudinally coupled resonator type elastic wave filter 6b has IDT electrodes 8bB1 to 8bB3. Reflectors 10Bb are provided on both sides of the IDT electrodes 8bB1 to 8bB3 in the elastic wave propagation direction.

  Although not shown in FIG. 3, the IDT electrode 8bA1 of the first longitudinally coupled resonator type elastic wave filter 6a has a first narrow pitch portion on the IDT electrode 8bA2 side. The IDT electrode 8bA2 has a second narrow pitch portion and a third narrow pitch portion on the IDT electrode 8bA1 side and the IDT electrode 8bA3 side. The IDT electrode 8bA3 has a fourth narrow pitch portion on the IDT electrode 8bA2 side. Similarly, the IDT electrodes 8bB1 to 8bB3 of the second longitudinally coupled resonator type elastic wave filter 6b also have first to fourth narrow pitch portions.

  In this embodiment, each IDT electrode of each acoustic wave resonator is formed as shown in Table 1 below, although not particularly limited thereto. Although not particularly limited, each IDT electrode of each longitudinally coupled resonator type elastic wave filter is formed as shown in Table 2 below. Each IDT electrode in the first and second band pass filters is made of Al. Each IDT electrode may be made of an appropriate metal other than Al. Further, each reflector is formed as shown in Table 1 and Table 2, although not particularly limited. Each reflector is made of the same material as each IDT electrode.

  Hereinafter, an example of a method of manufacturing the duplexer 1, which is the elastic wave device of the first embodiment, will be described.

  4A to 4D are schematic front cross-sectional views for explaining the method of manufacturing the acoustic wave device according to the first embodiment.

  As shown in FIG. 4A, a piezoelectric substrate 7 is prepared. Next, the metal film 8A is formed on the piezoelectric substrate 7. A plurality of IDT electrodes are formed by patterning this metal film 8A by photolithography.

  More specifically, next, a photosensitive material layer 9 made of a photoresist or the like is laminated on the metal film 8A. Next, as shown in FIG. 4B, the photosensitive material layer 9 is exposed to light to form a reaction portion 9 a in the photosensitive material layer 9. At this time, the exposure for forming all the elastic wave resonators in the duplexer 1 of this embodiment is collectively performed. Thereby, productivity can be effectively increased.

  A pattern A schematically shown in FIG. 4B is a pattern for forming the IDT electrode of the acoustic wave resonator in the first bandpass filter 2a shown in FIG. The pattern B is a pattern for forming the IDT electrode of the longitudinally coupled resonator type elastic wave filter in the second band pass filter 2b.

  At this time, patterns A and B are formed so that the duty of each IDT electrode of the first and second band pass filters 2a and 2b is made different. More specifically, the patterns A and B are formed so that the frequency dependences of the line widths of the electrode fingers of the IDT electrodes of the first and second band pass filters 2a and 2b are uniform.

  Next, as shown in FIG. 4C, the reaction part 9a of the photosensitive material layer 9 is removed by a developing solution or the like. Thereby, the photosensitive material layer 9 is patterned.

  Next, the portion of the metal film 8A exposed from the photosensitive material layer 9 is removed by etching to form the IDT electrodes 8a and 8b shown in FIG. 4D. Next, the photosensitive material layer 9 is removed. As a result, each acoustic wave resonator is formed, and the first and second band pass filters 2a and 2b shown in FIG. 1 are formed.

  A lift-off method may be used when forming the first and second band pass filters 2a and 2b.

  Here, using FIGS. 5 to 7, patterns A and B are formed so that the frequency dependences of the line widths of the electrode fingers of the IDT electrodes in the first and second band pass filters 2a and 2b are equalized. The method for doing so will be described more specifically. The results shown in FIGS. 5 to 7 are the results of the first and second band pass filters 2a and 2b in which the IDT electrodes and the reflectors are formed as shown in Tables 1 and 2 above. is there.

  FIG. 5 shows the line width of the electrode finger of each IDT electrode in the first band pass filter when the duty of each IDT electrode of the first band pass filter in the first embodiment is 0.55. It is a figure which shows the dependence of a frequency. FIG. 6 shows the line width of the electrode finger of each IDT electrode in the second band pass filter when the duty of each IDT electrode of the second band pass filter in the first embodiment is 0.65. It is a figure which shows the dependence of a frequency. FIG. 7 is a diagram showing the relationship between the frequency dependence of the line width of the electrode finger of each IDT electrode and the duty of each IDT electrode in the first and second bandpass filters of the first embodiment. is there.

  5 and 6 each show the above dependency of the frequency at a constant duty, and FIG. 7 shows the above dependency of the frequency at a plurality of duties.

  In addition, in FIG. 7, a square plot and a solid line C show the result in the first band-pass filter. The triangular plot and dashed line D show the results for the second bandpass filter. An alternate long and short dash line E indicates the above dependency when the duty of each IDT electrode in the first band pass filter is 0.5.

  As shown in FIG. 5, it can be seen that the frequency decreases as the line width of the electrode finger of the IDT electrode in the first bandpass filter increases. This relationship can be expressed as the following Expression 1 where the frequency is y and the line width of the electrode finger of the IDT electrode is x.

  y=−86.533x+1844.1...Equation 1

  Similarly, the relationship between the line width of the electrode finger of the IDT electrode and the frequency in the second bandpass filter shown in FIG. 6 can be expressed by the following Expression 2.

  y=-140.6x+2152 Formula 2

  On the other hand, FIG. 7 shows the results of obtaining the dependence of the frequency on the line width of the electrode finger of each IDT electrode in the first and second band pass filters by varying the duty of each IDT electrode. Note that FIG. 5 and FIG. 7 show the above-mentioned dependence of the frequency at the end portion on the high frequency side of the pass band of the first band pass filter. FIG. 6 and FIG. 7 show the above-mentioned dependence of the frequency at the lower end of the pass band of the second band pass filter.

  As shown in FIG. 7, it can be seen that as the duty of each IDT electrode in the first bandpass filter increases, the frequency dependence of the line width of the electrode finger of the IDT electrode decreases. This relationship can be expressed as in the following Expression 3 when the frequency dependence of the line width of the electrode finger of the IDT electrode is y and the duty is x. Similarly, the relationship between the frequency dependence and the duty with respect to the line width of the electrode finger of the IDT electrode in the second bandpass filter can be expressed by the following Expression 4.

y=376.5x−274.8 Equation 3
y=1059.5x−776.8 Equation 4

  Here, for example, at the intersection of the solid line C and the broken line D in FIG. 7 and the alternate long and short dash line E, the above-mentioned dependences in the first and second band pass filters are both -88.55. I have them all. More specifically, the above dependency on the frequency of the high band side end of the pass band of the first band pass filter and the frequency of the low band side end of the pass band of the second band pass filter. The above-mentioned dependency in 1 is aligned.

  In FIG. 7, the pattern A shown in FIG. 4B is formed so that the duty is equivalent to the portion where the alternate long and short dash line E and the solid line C intersect. Similarly, the pattern B is formed so that the duty is equivalent to the portion where the alternate long and short dash line E and the broken line D intersect. More specifically, the patterns A and B are formed so that the duty of each IDT electrode in the first and second band pass filters is 0.5 and 0.651, respectively.

  The duty of each IDT electrode in the first and second band-pass filters is not limited to the above value, and may be set to an appropriate value with which the frequency dependence of the line width of the electrode finger of the IDT electrode is uniform. ..

  Even if the line width of the electrode fingers of each IDT electrode deviates from the design value due to the variation in exposure in the process shown in FIG. The line widths of are likewise displaced. Since the dependence of the frequency on the line width of the electrode finger of each IDT electrode is uniform, the pass bands of the first and second band pass filters are similarly displaced. Therefore, the gap between the frequencies of the passbands of the first and second bandpass filters is unlikely to occur. Therefore, it is possible to easily adjust the frequencies in the pass bands of the first and second band pass filters.

  In the duplexer 1 of the present embodiment shown in FIG. 1, the pass band of the second band pass filter 2b is located higher than the pass band of the first band pass filter 2a. At this time, as described above, the above dependency at the high band side end of the pass band of the first band pass filter 2a and the low band side end of the pass band of the second band pass filter 2b. It is preferable to match the above dependency in. As a result, the gap between the frequencies of the passbands of the first and second bandpass filters 2a and 2b is further unlikely to occur.

  However, the above-mentioned dependences of specific frequencies other than the end portions in the pass bands of the first and second band pass filters 2a and 2b may be made uniform.

  FIG. 8 is a schematic diagram of a multiplexer according to the second embodiment.

  The multiplexer 11 has first to third band-pass filters 12a to 12c as a plurality of elastic wave filter units commonly connected to the antenna terminal 4. Each of the first to third band pass filters 12a to 12c has an IDT electrode. The pass band of the first band pass filter 12a is located higher than the pass band of the second band pass filter 12b. The pass band of the second band pass filter 12b is located higher than the pass band of the third band pass filter 12c.

  Similar to the first embodiment, in the first to third band pass filters 12a to 12c, the duty of each IDT electrode is different so that the dependence of the frequency on the line width of the electrode finger of each IDT electrode is uniform. ing. Therefore, it is possible to easily adjust the frequencies in the pass bands of the first to third band pass filters 12a to 12c.

  The number of bandpass filters in the multiplexer 11 is not particularly limited, and four or more bandpass filters may be commonly connected.

  The multiplexer 11 can be manufactured by providing the first to third band pass filters 12a to 12c by the same method as the method of manufacturing the duplexer 1 of the first embodiment. At this time, the dependence of the frequencies of the end portions of the pass bands in at least two band pass filters among the first to third band pass filters 12a to 12c on the line width of the electrode fingers of the IDT electrodes is made uniform. Is preferred. As a result, the frequency intervals of the passbands are unlikely to shift.

  More preferably, it is desirable that the band-pass filters having the smallest difference between the pass bands have the same dependency as in the first embodiment. More specifically, the frequency of the low band side end of the pass band of the first band pass filter 12a and the frequency of the high band side end of the pass band of the second band pass filter 12b Align the above dependencies. In addition, the above-mentioned dependence between the frequency of the low band side end of the pass band of the second band pass filter 12b and the frequency of the high band side end of the pass band of the third band pass filter 12c. Align. This makes it even more difficult for the frequency intervals of the passbands to shift.

  FIG. 9 is a circuit diagram of an elastic wave device according to the third embodiment.

  The elastic wave device 21 of the present embodiment is a ladder-type filter having a series arm resonators S21 to S23 and parallel arm resonators P21 and P22 as a plurality of elastic wave resonator portions.

  More specifically, the series arm resonators S21 to S23 are connected in series between the input terminal 23 and the output terminal 24. The parallel arm resonator P21 is connected between the connection point between the series arm resonator S21 and the series arm resonator S22 and the ground potential. The parallel arm resonator P22 is connected between the connection point between the series arm resonator S22 and the series arm resonator S23 and the ground potential.

  The series arm resonators S21 to S23 and the parallel arm resonators P21 and P22 each have an IDT electrode. The duty of each IDT electrode is different so that the series arm resonators S21 to S23 and the parallel arm resonators P21 and P22 have the same dependence of the resonance frequency on the line width of the electrode finger of each IDT electrode. Therefore, the resonance frequency of each elastic wave resonator portion can be easily adjusted.

  The dependency of each acoustic wave resonator section may be the dependency of a specific frequency other than the resonance frequency on the line width of the electrode finger of each IDT electrode.

  The elastic wave device 21 is not limited to the ladder type filter, and may be any elastic wave filter having a plurality of elastic wave resonator portions having the same dependency.

1... Duplexer 2a, 2b... 1st, 2nd band pass type filter 3... Input terminal 4... Antenna terminal 5... Output terminal 6a, 6b... 1st, 2nd longitudinal coupling resonator type elastic wave filter 6x1, 6x2 ... Connection point 7... Piezoelectric substrate 8A... Metal films 8a, 8b, 8aA, 8bA1-8bA3, 8bB1-8bB3... IDT electrode 9... Photosensitive material layer 9a... Reaction parts 10A, 10Ba, 10Bb... Reflector 11... Multiplexer 12a... 12c... 1st-3rd band pass type filter 21... Elastic wave device 23... Input terminal 24... Output terminal C... Capacitance L1, L2, L3... 1st-3rd inductor S1a, S1b, S2a, S2b, S3a , S3b, S4, S5a to S5c, S21 to S23... Series arm resonators S11a to S11c... Acoustic wave resonators P1a, P1b, P2a, P2b, P3, P4a, P4b, P21, P22... Parallel arm resonators P11a, P11b. ...Elastic wave resonator

Claims (2)

A step of preparing a piezoelectric substrate,
Forming a metal film on the piezoelectric substrate,
Patterning the metal film by photolithography to form a plurality of IDT electrodes to form a plurality of acoustic wave element portions having different frequencies;
Equipped with
The plurality of acoustic wave element portions are formed by collectively performing exposure in a photolithography method,
The plurality of elastic wave element portions are a plurality of elastic wave filter portions,
Of the plurality of elastic wave filter units, in the two elastic wave filter units having different pass bands and the smallest difference between the pass bands, the IDT in the elastic wave filter unit having the pass band located on the high frequency side. By making the duty of the electrode different from the duty of the IDT electrode in the elastic wave filter unit whose pass band is located on the low frequency side, the low pass band of the elastic wave filter unit whose pass band is located on the high frequency side is obtained. The dependence of the frequency of the end portion on the band side and the frequency of the end portion on the high band side of the pass band in the elastic wave filter section where the pass band is located on the low band side on the line width of the electrode finger of the IDT electrode is shown. A method for manufacturing an elastic wave device.   The method for manufacturing an elastic wave device according to claim 1, wherein a multiplexer is formed in which the plurality of elastic wave filter units are commonly connected.

Images