JP5206128B2 - Elastic wave device and manufacturing method thereof - Google Patents

Description

  The present invention relates to an acoustic wave device and a manufacturing method thereof, and more particularly to an acoustic wave device including a signal-side probe pad for inspection and a ground-side probe pad and a manufacturing method thereof.

Conventionally, for example, Patent Document 1 discloses a band-pass filter in which a probe pad for inspection is provided in the periphery. FIG. 18 is a schematic plan view of the bandpass filter 100 disclosed in Patent Document 1. As shown in FIG. As shown in FIG. 18, the band pass filter 100 is a ladder type band pass filter, and a plurality of resonators 101 are connected in a ladder type. Inspection probe pads 20-1 to 20-8 are electrically connected to each resonator 101. For example, the probe pad 20-3 and the probe pad 20-6 are electrically connected to the parallel arm resonator 101a. In the band pass filter 100, the probe pad 20-3 and the probe pad 20-6 are arranged separately on both sides of the resonator 101a. Specifically, the probe pad 20-3 is arranged on one side of the propagation direction of the elastic wave of the resonator 101a, whereas the probe pad 20-6 is arranged in the propagation direction of the elastic wave of the resonator 101a. Arranged on the other side.
JP-A-6-177690

  As described above, in the band-pass filter 100 disclosed in Patent Document 1, the pair of probe pads are arranged separately on both sides of the resonator. For this reason, the distance between the pair of probe pads tends to be longer. Therefore, there is a problem that it is difficult to measure the frequency characteristics of the resonator with high measurement accuracy.

  An object of the present invention is to provide an elastic wave device capable of measuring frequency characteristics with high accuracy.

  The acoustic wave device according to the present invention includes a piezoelectric body, an IDT, a first wiring, a second wiring, a first probe pad, and a second probe pad. Each of the IDT, the first wiring, the second wiring, the first probe pad, and the second probe pad is formed on the piezoelectric body. The IDT has first and second comb electrodes interleaved with each other. The first wiring is electrically connected to the first comb electrode. The second wiring is electrically connected to the second comb electrode. The first probe pad is electrically connected to the first wiring. The second probe pad is electrically connected to the second wiring. Both the first probe pad and the second probe pad are disposed on one side in the first direction with respect to the IDT. The first wiring is drawn from the first probe pad to one side in the second direction perpendicular to the first direction, while the second wiring is drawn from the second probe pad to the other side in the second direction. Has been drawn to.

  In a specific aspect of the acoustic wave device according to the present invention, the direction of drawing out the first wiring from the first probe pad and the direction of drawing out the second wiring from the second probe pad are parallel to each other. is there.

  In another specific aspect of the acoustic wave device according to the present invention, the first probe pad and the second probe pad are arranged on an imaginary straight line extending in the second direction.

  In another specific aspect of the acoustic wave device according to the present invention, a third wiring formed on the piezoelectric body, electrically connected to the second comb electrode, and formed on the piezoelectric body. And a third probe pad electrically connected to the third wiring and disposed on one side in the first direction with respect to the IDT, wherein the third wiring is the third probe pad. To the other side in the second direction.

  In still another specific aspect of the acoustic wave device according to the present invention, the first probe pad is a signal-side probe pad, and the second and third probe pads are ground-side probe pads.

  In still another specific aspect of the elastic wave device according to the present invention, the first direction is a direction parallel to or perpendicular to the propagation direction of the elastic wave.

  The elastic wave device according to the present invention may further include a dielectric formed on the piezoelectric body so as to cover the IDT.

  The ladder-type elastic wave filter according to the present invention includes the elastic wave device according to the present invention as at least one of a series arm elastic wave resonator and a parallel arm elastic wave resonator.

  The first method for manufacturing an acoustic wave device according to the present invention relates to a method for manufacturing the acoustic wave device according to the present invention, and includes an IDT, first and second wirings, and first and second on a piezoelectric substrate. Forming a probe pad, and connecting the signal terminal of the frequency characteristic measuring device to one of the first probe pad and the second probe pad, and the first probe pad and the second probe pad And measuring the frequency characteristics by connecting the other of the two to a ground terminal.

  The second method for manufacturing an acoustic wave device according to the present invention includes a step of forming a plurality of sets of IDTs, first and second wires, and first and second probe pads on a piezoelectric wafer formed of a piezoelectric material. The signal terminal of the frequency characteristic measuring device is connected to one of the first probe pad and the second probe pad, and the other of the first probe pad and the second probe pad is connected to the ground terminal. A measuring step of measuring frequency characteristics of at least one of the plurality of sets of IDTs, the first and second wirings, and the first and second probe pads, and a step of cutting the piezoelectric wafer into a plurality of piezoelectric substrates And.

  The method for manufacturing the first and second acoustic wave devices according to the present invention further includes a step of determining whether or not the frequency characteristic measured in the measurement step is within a predetermined frequency characteristic range. There may be.

  The first and second methods of manufacturing an elastic wave device according to the present invention include a frequency characteristic of the elastic wave device according to the frequency characteristic measured in the measurement step, and a target frequency characteristic of the predetermined elastic wave device. A step of reducing the thickness of the IDT may be further provided so as to reduce the difference between the thickness and the IDT.

  The first and second methods of manufacturing an acoustic wave device according to the present invention are performed prior to the measurement step, and a dielectric formation step of forming a dielectric so as to cover the IDT, and frequency characteristics measured in the measurement step A step of adjusting the thickness of the dielectric so that the difference between the frequency characteristic of the elastic wave device according to the frequency characteristic and a target frequency characteristic of the predetermined elastic wave device is reduced. There may be.

  In the acoustic wave device according to the present invention, since both the first probe pad and the second probe pad are arranged on one side in the first direction with respect to the IDT, the first probe pad and the second probe pad Since the distance between the probe pad and the probe pad can be shortened, the frequency characteristic can be measured with high accuracy. In addition, the first wiring is drawn from the first probe pad to one side in the second direction perpendicular to the first direction, while the second wiring is drawn from the second probe pad in the second direction. Since it is pulled out to the other side, it is possible to reduce the variation in the measurement of the frequency characteristic caused by the variation in the contact position of the signal terminal and the ground terminal with respect to the first and second probe pads, so that the measurement of the frequency characteristic can be performed with higher accuracy. Is possible.

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

(First embodiment)
FIG. 1 is a schematic plan view of a boundary acoustic wave resonator 1 according to the first embodiment. 2 and 3 are cross-sectional views of the boundary acoustic wave resonator 1. However, in FIG. 1, the dielectric 20 is not shown.

  As shown in FIGS. 2 and 3, the boundary acoustic wave resonator 1 includes a piezoelectric body 10. The main surface 10a of the piezoelectric body 10 includes the IDT 11, the grating reflectors 12a and 12b, the first to third wirings 13 to 15, and the first to third probe pads 16 to 18 shown in FIG. Is formed. As shown in FIGS. 2 and 3, a dielectric 20 is formed on the main surface 10 a of the piezoelectric body 10. The dielectric 20 is formed so as to cover substantially the entire main surface 10 a, and the IDT 11 and the grating reflectors 12 a and 12 b are covered with the dielectric 20. As shown in FIG. 2, openings 20 a to 20 c are formed in portions corresponding to the positions of the first to third probe pads 16 to 18 of the dielectric 20. The first to third probe pads 16 to 18 are exposed from the dielectric 20 through the openings 20a to 20c.

The material of each of the piezoelectric body 10 and the dielectric body 20 is not particularly limited as long as it is a combination that generates a boundary acoustic wave at the boundary between the piezoelectric body 10 and the dielectric body 20. For example, the dielectric 20 _is, SiO 2, SiON, or may be formed of SiN or the like. The piezoelectric body 10 may be made of, for example, LiNbO ₃ , LiTaO ₃ , Ta ₂ O ₅ , Nb ₂ O ₅ or the like.

  Further, the thicknesses of the piezoelectric body 10 and the dielectric body 20 are not particularly limited, and are appropriately set according to the characteristics of the boundary acoustic wave resonator 1.

  As shown in FIG. 1, the IDT 11 includes a first comb electrode 21 and a second comb electrode 22. The first comb electrode 21 and the second comb electrode 22 are interleaved with each other. Specifically, each of the first comb electrode 21 and the second comb electrode 22 includes bus bars 21a and 22a and one or a plurality of electrode fingers 21b and 22b connected to the bus bars 21a and 22a. The electrode fingers 21b of the first comb electrode 21 and the electrode fingers 22b of the second comb electrode 22 are alternately arranged in the elastic wave propagation direction Y.

The first grating reflectors 12a is disposed on the _{Y 1} side in the propagation direction Y of the acoustic wave IDT 11. On the other hand, the second grating reflectors 12b is disposed on the _{Y 2} side in the propagation direction Y of the acoustic wave IDT 11.

  The materials of the IDT 11, the first to third wirings 13 to 15 and the first to third probe pads 16 to 18 are not particularly limited as long as they are conductive materials. Each of the IDT 11, the first to third wirings 13 to 15 and the first to third probe pads 16 to 18 is, for example, one of Pt, Au, Cu, Ag, Al, W, or Pt, Au, It is formed of an alloy obtained by adding other elements to Cu, Ag, Al, and W. The IDT 11, the first to third wirings 13 to 15, and the first to third probe pads 16 to 18 may be formed of different materials. However, from the viewpoint of ease of manufacture, the IDT 11, the first to third wirings 13 to 15, and the first to third probe pads 16 to 18 are preferably formed of the same material.

  The first comb electrode 21 is electrically connected to the first probe pad 16 via the first wiring 13. On the other hand, the second comb electrode 22 is electrically connected to the second probe pad 17 via the second wiring 14 and also connected to the third probe pad 18 via the third wiring 15. Are also electrically connected.

  In the present embodiment, an example in which the first probe pad 16 is a signal-side probe pad and the second and third probe pads 17 and 18 are ground-side probe pads will be described. However, the first probe pad 16 may be a ground-side probe pad, and the second and third probe pads 17 and 18 may be signal-side probe pads.

In the present embodiment, it is arranged on the X ₁ side of the perpendicular direction perpendicular X to the propagation direction Y of the elastic wave of all the first to third probe pads 16 to 18 IDT 11. More specifically, the first to third probe pads 16 to 18, located on the _{X 1} side of the IDT 11, are arranged on an imaginary straight line L extending in the propagation direction Y of the elastic wave.

  Here, “the first to third probe pads 16 to 18 are arranged on a virtual straight line” means that all of the first probe pad 16, the second probe pad 17, and the third probe pad 18 are present. Means that there is a virtual straight line L that passes through the center of the first probe pad 16, the second probe pad 17, and the third probe pad 18. It is not always necessary to have a virtual straight line that passes through the centers of the first probe pad 16, the second probe pad 17, and the third probe pad 18.

First wiring 13 is routed to the Y ₂ side of the propagation direction Y of the elastic wave from the bus bar 21a of the first comb electrode 21. The first wiring 13 is connected to the first probe pad 16 via the Y ₂ side of the first probe pad 16. A connection portion 13 a of the first wiring 13 with the first probe pad 16 extends from the first probe pad 16 to the Y ₂ side in the elastic wave propagation direction Y. In other words, the first wiring 13 is drawn to the Y ₂ side of the propagation direction Y of the elastic wave from the first probe pad 16.

The second wire 14, are routed to the Y ₂ side of the propagation direction Y of the elastic wave from the bus bar 22a of the second comb electrode 22. The second wiring 14 is connected to the second probe pad 17 via the Y ₂ side of the second grating reflector 12 b and the Y ₁ side of the second probe pad 17. A connection portion 14 a of the second wiring 14 with the second probe pad 17 extends from the second probe pad 17 to the Y ₁ side in the elastic wave propagation direction Y. In other words, the second wire 14 is drawn to the Y ₁ side of the propagation direction Y of the elastic wave from the second probe pad 17.

Third wire 15, are routed to the Y ₁ side of the propagation direction Y of the elastic wave from the bus bar 22a of the second comb electrode 22. The third wiring 15 is connected to the third probe pad 18 via the Y ₁ side of the first grating reflector 12 a and the Y ₁ side of the third probe pad 18. A connection portion 15 a of the third wiring 15 with the third probe pad 18 extends from the third probe pad 18 to the Y ₁ side in the elastic wave propagation direction Y. In other words, the third wire 15 is drawn to the Y ₁ side of the propagation direction Y of the elastic wave from the second probe pad 17.

  In the present embodiment, the connection portion 13a of the first wiring 13, the connection portion 14a of the second wiring 14, and the connection portion 15a of the third wiring 15 are formed in parallel to each other.

As described above, in the present embodiment, as shown in FIG. 1, all of the first to third probe pads 16 to 18 are arranged on the X ₁ side of the IDT 11. For this reason, for example, compared with the case where the first probe pad 16 that is a signal side probe pad and the second and third probe pads 17 and 18 that are ground side probe pads are arranged separately on both sides of the IDT 11. Thus, the electrode distance between the first probe pad 16 and the second and third probe pads 17 and 18 can be shortened. Therefore, the frequency characteristic can be measured with high accuracy.

  In particular, in the present embodiment, the first to third probe pads 16 to 18 are arranged on a virtual straight line L extending in the elastic wave propagation direction Y. For this reason, the electrode distance between the first probe pad 16 and the second and third probe pads 17 and 18 can be further shortened. Therefore, the frequency characteristic can be measured with higher accuracy.

  Incidentally, for example, as shown in FIG. 4, connection portions 113 a to 115 a of the first to third wirings 113 to 115 to the first to third probe pads 116 to 118 are connected to the first to third probe pads 116 to 116. It is also conceivable to pull out from 118 in the vertical direction Y. However, when the connection portions 113a to 115a are pulled out from the first to third probe pads 116 to 118 in the vertical direction Y, as described below, signal terminals for the first to third probe pads 116 to 118 and As the contact position of the ground terminal varies, the measured frequency characteristics tend to vary.

  In FIG. 4, the elastic wave propagation direction is X. The direction in which the connecting portions 113a to 115a are pulled out from the probe pads 116 to 118 is Y.

For example, the signal terminal of the frequency measuring device (not shown) is brought into contact with the position P _1-1 of the first probe pad 116 shown in FIG. 4 and the ground terminal is connected to the position P _2-1 of the second probe pad 117 and the first position. When the probe terminal 118 is in contact with the position P _3-1 of the third probe pad 118, the signal terminal is brought into contact with P _1-2 shifted to the Y ₂ side from the position P _1-1 by the distance l, and the ground terminal is positioned. The electrode distance between the signal terminal and the IDT 111 is compared with the case where P _2-1 and the position P _3-1 are brought into contact with P _2-2 and P _3-2 which are shifted to the Y ₂ side by the distance l, respectively. Does not substantially change, whereas the electrode distance between the ground terminal and the IDT 111 changes. Specifically, the electrode distance between the ground terminal in contact with the second probe pad 117 and the IDT 111 is shortened by about l, whereas the ground in contact with the third probe pad 118. The electrode distance between the terminal and the IDT 111 is increased by about l. Therefore, the parasitic inductance between the ground terminal in contact with the second probe pad 117 and the IDT 111 is increased, while the parasitic inductance between the ground terminal in contact with the third probe pad 118 and the IDT 111 is increased. Decrease. Thus, since the parasitic inductance between the signal terminal and the ground terminal varies depending on the contact position between the signal terminal and the ground terminal, the measured frequency characteristics tend to vary.

In contrast, in the present embodiment, while the first wiring 13 are drawn out from the first probe pad 16 on the Y ₂ side, each of the second and third wiring 14, 15 the second and third It is drawn to _{Y 1} side from the probe pads 17, 18. Therefore, _P 1-1 the contact position between the signal terminals and the ground terminals shown in FIG. _{1, P 2-1,} P 1-2 from _{P 3-1, P 2-2,} was changed to _{P 3-2} In this case, the electrode distance between the signal terminal and the IDT 11 is shortened by the distance l, while the electrode distance between the ground terminal and the IDT 11 is increased by the distance l. Therefore, since the parasitic inductance between the signal terminal and the IDT 11 is reduced by a magnitude corresponding to the distance l, the parasitic inductance between the ground terminal and the IDT 11 is increased by a magnitude corresponding to the distance l. The parasitic inductance between the ground terminal and the ground terminal does not substantially change as a whole. Therefore, the contact position between the signal terminals and the ground terminal _{P 1-1, P 2-1, P} 1-2 from _{P 3-1,} P _2-2, even when the change to _{P 3-2} The frequency characteristics to be measured are less likely to vary.

  In particular, in the present embodiment, since the connecting portion 13a, the connecting portion 14a, and the connecting portion 15a are parallel to each other, the electrode distance between the signal terminal and the ground terminal is further suppressed, and the measurement variation of the frequency characteristics is reduced. Occurrence is suppressed more effectively.

  Note that one signal-side probe pad and one ground-side probe pad may be provided, but at least one of the signal-side probe pad and the ground-side probe pad may be provided. In this embodiment, since a plurality of ground-side probe pads are provided, the ground in frequency characteristic measurement is further strengthened.

  The boundary acoustic wave resonator 1 of the present embodiment may be used alone or in combination. For example, as shown in FIG. 5, a ladder-type elastic wave filter 2 may be configured using the boundary acoustic wave resonator 1 shown in FIG. 1 as a series arm boundary acoustic wave resonator and a parallel arm boundary acoustic wave resonator. . As shown in FIG. 5, the resonance frequency may be measured by providing a probe pad only for one series arm boundary acoustic wave resonator. Even in the ladder-type elastic wave filter 2 including the boundary acoustic wave resonator 1 as the serial arm boundary acoustic wave resonator and the parallel arm boundary acoustic wave resonator, the frequency characteristics can be performed with high accuracy as described above.

  In addition, although the boundary acoustic wave resonator 1 was mentioned as an example of the elastic wave apparatus which implemented this invention, the elastic wave apparatus of this invention is not limited to a boundary acoustic wave apparatus, A surface acoustic wave apparatus may be sufficient. . Specifically, for example, the dielectric 20 may not be provided.

  The elastic wave device of the present invention may use any kind of boundary acoustic wave or surface acoustic wave.

(Manufacturing method of boundary acoustic wave resonator 1)
Although the manufacturing method of the boundary acoustic wave resonator 1 is not specifically limited, For example, it can manufacture in the following procedures.

  For example, as shown in FIG. 6, first, in step S <b> 1, the IDT 11, the first to third wirings 13 to 15, and the first to third probe pads 16 to 18 are formed on the piezoelectric body 10.

  Next, in step S <b> 2, the dielectric 20 is formed on the piezoelectric body 10.

  Next, in step S3, frequency characteristics are measured. Specifically, with the signal terminal of the frequency measuring device in contact with the first probe pad 16, the ground terminal of the frequency measuring device is in contact with each of the second and third probe pads 17, 18, The frequency characteristic of the boundary acoustic wave resonator 1 is measured.

  In the present embodiment, “frequency characteristics” refers to all characteristics related to frequency. The frequency characteristic includes, for example, a resonance frequency and an anti-resonance frequency when the elastic wave device is a resonator as in this embodiment, and a center frequency when the elastic wave device is a filter. It is.

  In step S4, the quality of the manufactured boundary acoustic wave resonator 1 is determined. Specifically, it is determined whether or not the measurement result of the frequency characteristic in step S3 is within the range of the frequency characteristic predetermined as the target frequency characteristic of the boundary acoustic wave resonator 1. When the measurement result of the frequency characteristic is within a predetermined frequency characteristic range, it is determined as a non-defective product. If the measurement result of the frequency characteristic is not within the predetermined frequency characteristic range, it is determined as a defective product.

  As described above, since the boundary acoustic wave resonator 1 can measure the frequency characteristics with high accuracy regardless of the contact position of the signal terminal and the ground terminal, according to the manufacturing method, the quality of the boundary acoustic wave resonator 1 is acceptable. Can be reliably determined.

(Second Embodiment)
In the first embodiment, the manufacturing method in the case where the boundary acoustic wave resonators 1 are manufactured one by one has been described. However, for example, as shown in FIG. 7, a plurality of boundary acoustic wave resonators 1 may be manufactured simultaneously using a piezoelectric wafer.

  In the example shown in FIG. 7, first, in step S10, a piezoelectric wafer 30 (see FIG. 8) formed of a piezoelectric material is prepared.

  Next, in step S11, as shown in FIG. 8, a plurality of sets of IDT 11, first to third wirings 13 to 15 and first to third probe pads 16 to 18 are formed on the piezoelectric wafer 30 in a matrix form. To form.

  Next, in step S <b> 12, a dielectric is formed on the piezoelectric wafer 30. As a result, the plurality of boundary acoustic wave resonators 1 are integrally formed.

  Next, in step S <b> 13, frequency characteristics are measured for at least one boundary acoustic wave resonator 1. Specifically, with the signal terminal of the frequency measuring device in contact with the first probe pad 16, the ground terminal of the frequency measuring device is in contact with each of the second and third probe pads 17, 18, The frequency characteristic of at least one boundary acoustic wave resonator 1 is measured.

  Next, in step S14, the quality of the boundary acoustic wave resonator 1 is determined. Specifically, it is determined whether or not the measurement result of the frequency characteristic in step S13 is within the range of the frequency characteristic predetermined as the target frequency characteristic of the boundary acoustic wave resonator 1. When the measurement result of the frequency characteristic is within a predetermined frequency characteristic range, it is determined as a non-defective product. If the measurement result of the frequency characteristic is not within the predetermined frequency characteristic range, it is determined as a defective product.

  If it is determined that the product is non-defective in step S14, the process proceeds to step S15. In step S15, the piezoelectric body 30 shown in FIG. 1 is formed by cutting the piezoelectric wafer 30 along the cut line C.

  On the other hand, if it is determined that the product is defective in step S14, the process proceeds to step S16 and is discarded or collected.

  As in this embodiment, by measuring the frequency characteristics before the piezoelectric wafer 30 is cut, it is not always necessary to measure the frequency characteristics for each boundary acoustic wave resonator 1, and the piezoelectric wafer 30 is formed on the piezoelectric wafer 30. By measuring the frequency characteristics of only one boundary acoustic wave resonator 1 among the plurality of boundary acoustic wave resonators 1, it is possible to determine whether all the boundary acoustic wave resonators 1 are good or bad. Therefore, the frequency characteristic measurement process can be simplified, and the boundary acoustic wave resonator 1 can be manufactured more easily.

(Third embodiment)
In the first and second embodiments, the example in which the quality determination of the boundary acoustic wave resonator 1 is performed using the measured frequency characteristics has been described. However, steps other than pass / fail judgment may be performed using the measurement result of the frequency characteristics. For example, as shown in FIG. 9, the frequency characteristics may be adjusted using the measured frequency characteristics.

  In the example illustrated in FIG. 9, as in the second embodiment, after performing Step S <b> 10 and Step S <b> 11 and before performing Step S <b> 12, the frequency characteristics in a state where the dielectric 20 is not formed in Step S <b> 20. Measure. That is, the frequency characteristic is measured in the state of the surface acoustic wave device.

  Next, in step S21, the thickness of the IDT 11 is adjusted. Specifically, the thickness that reduces the difference between the frequency characteristic of the boundary acoustic wave resonator 1 corresponding to the frequency characteristic measured in step S20 and the target frequency characteristic of the boundary acoustic wave resonator 1 determined in advance. Thus, the thicknesses of the first and second comb electrodes 21 and 22 constituting the IDT 11 are reduced. A method for reducing the thickness of the IDT 11 is not particularly limited. For example, the thickness of the IDT 11 can be reduced by etching or polishing.

  In the present specification, the “frequency characteristic of the elastic wave device according to the measured frequency characteristic” refers to the frequency characteristic of the elastic wave device estimated from the measurement result of the frequency characteristic. For this reason, the frequency characteristic of the boundary acoustic wave resonator 1 according to the frequency characteristic measured in step S20 refers to the frequency characteristic of the boundary acoustic wave resonator 1 estimated from the frequency characteristic measured in step S20.

  Subsequently, in step S12, the dielectric 20 is formed. Next, in step S22, the piezoelectric wafer 30 is cut, and a plurality of boundary acoustic wave resonators 1 are completed.

  As in the present embodiment, by adjusting the thickness of the IDT 11 according to the measurement result of the frequency characteristics, the yield rate of the boundary acoustic wave resonator 1 can be increased. As a result, the cost of the boundary acoustic wave resonator 1 can be reduced.

(Fourth embodiment)
In the third embodiment, the example in which the frequency characteristic is adjusted by adjusting the thickness of the IDT 11 has been described. However, in the present invention, the frequency characteristic adjustment method is not particularly limited. For example, as shown in FIG. 10, the frequency characteristics may be adjusted by adjusting the thickness of the dielectric 20.

  Specifically, as shown in FIG. 10, after performing Steps S10 to S13 as in the second embodiment, the thickness of the dielectric 20 is adjusted in Step S31. Specifically, the thickness that reduces the difference between the frequency characteristic of the boundary acoustic wave resonator 1 corresponding to the frequency characteristic measured in step S13 and the target frequency characteristic of the boundary acoustic wave resonator 1 determined in advance. Thus, the thickness of the dielectric 20 is adjusted. The method for adjusting the thickness of the dielectric 20 is not particularly limited. When the thickness of the dielectric 20 is reduced, it can be performed by etching or polishing. The thickness of the dielectric 20 can be increased by further forming a dielectric on the dielectric 20.

  Next, in step S22, the piezoelectric wafer 30 is cut, and a plurality of boundary acoustic wave resonators 1 are completed.

  After the formation of the dielectric 20 as in the present embodiment, the frequency characteristics of the boundary acoustic wave resonator 1 manufactured more accurately are predicted by measuring the frequency characteristics of the boundary acoustic wave resonator. Therefore, the yield rate of the boundary acoustic wave resonator 1 can be further increased. As a result, the cost of the boundary acoustic wave resonator 1 can be further reduced.

(First modification)
In the above embodiment, the first and second probe pads 16, 17 has been described an example in which are arranged on X ₁ side of the vertical direction X with respect to IDT 11, for example, as shown in FIG. 11, the first The second probe pads 16 and 17 may be arranged on one side of the elastic wave propagation direction Y with respect to the IDT 11.

(Second modification)
In the above embodiment, the example in which the first to third wirings 13 to 15 and the grating reflectors 12a and 12b are not electrically connected has been described. However, at least one of the first to third wirings 13 to 15 is described. May be electrically connected to the grating reflectors 12a and 12b. For example, as shown in FIG. 12, the second wiring 14 may be formed via the grating reflector 12b.

(Third Modification)
In the above embodiment, the example in which the connection portions 13a, 14a, and 15a are formed in parallel to each other has been described. However, as shown in FIG. 13, the connecting portion 13a and the connecting portion 14a may be formed so as not to be parallel to each other.

(Example)
As shown in FIG. 1, an IDT 11 made of Au, first to third wirings 13 to 15 and first to third probe pads 16 to 18 are formed on a piezoelectric body 10 made of LiNbO _3. A dielectric 20 made of SiO ₂ was formed, and the boundary acoustic wave resonator 1 according to the example was completed.

  In the boundary acoustic wave resonator 1 according to the example, the signal terminal and the ground terminal were brought into contact with the centers of the first to third probe pads 16 to 18 to measure impedance and phase. The measurement result of the impedance is shown by a solid line with reference numeral 40 in FIG. The measurement result of the phase is shown by a solid line denoted by reference numeral 41 in FIG.

In the boundary acoustic wave resonator 1 according to the example, the signal terminal and the ground terminal were brought into contact with each other at a position shifted by 50 μm from the center to the Y ₁ side in the Y direction, and the impedance and the phase were measured. The measurement result of the impedance is shown by a one-dot broken line denoted by reference numeral 42 in FIG. The measurement result of the phase is shown by a one-dot broken line denoted by reference numeral 43 in FIG.

In the boundary acoustic wave resonator 1 according to the embodiment, it was conducted at a position shifted by 50μm in Y ₂ side of the Y direction from the center signal terminals, the measurement of contacting the ground terminal impedance and phase. The measurement result of the impedance is shown by a dotted line denoted by reference numeral 44 in FIG. The measurement result of the phase is indicated by a dotted line denoted by reference numeral 45 in FIG.

Further, in the boundary acoustic wave resonator 1 according to the embodiment, the signal terminal at a position shifted by 50μm in X ₁ side of the X direction from the center, the measurement of the impedance and phase by contacting the ground terminal was performed. Furthermore, in the boundary acoustic wave resonator 1 according to the embodiment, the signal terminal at a position shifted by 50μm in X ₂ side in the X direction from the center, the measurement of the impedance and phase by contacting the ground terminal was performed. A result is shown in FIG. 15 with the result at the time of making a signal terminal and a ground terminal contact the center of the 1st-3rd probe pads 16-18. In FIG. 15, three graphs are displayed as a single graph overlapping each other.

  As a comparative example, a boundary acoustic wave resonator having the same structure as that of the above example was manufactured except that the first to third wirings had the shape shown in FIG.

  In the boundary acoustic wave resonator according to the comparative example, the impedance and the phase were measured by bringing the signal terminal and the ground terminal into contact with the centers of the first to third probe pads. The measurement result of the impedance is shown by a solid line denoted by reference numeral 50 in FIG. The measurement result of the phase is shown by a solid line denoted by reference numeral 51 in FIG.

In the boundary acoustic wave resonator of the comparative example, the signal terminal at a position shifted by 50μm in Y ₁ side of the Y-direction from the center, the measurement of contacting the ground terminal impedance and phase were performed. The measurement result of the impedance is shown by a one-dot broken line denoted by reference numeral 52 in FIG. The measurement result of the phase is shown by a one-dot broken line denoted by reference numeral 53 in FIG.

In the boundary acoustic wave resonator of the comparative example, the signal terminal at a position shifted by 50μm in Y ₂ side of the Y-direction from the center, the measurement of contacting the ground terminal impedance and phase were performed. The measurement result of the impedance is shown by a dotted line denoted by reference numeral 54 in FIG. The measurement result of the phase is shown by a dotted line denoted by reference numeral 55 in FIG.

Moreover, was performed in a boundary acoustic wave resonator of the comparative example, the signal terminal at a position shifted by 50μm in X ₁ side of the X direction from the center, the measurement of the impedance and phase by contacting a ground terminal. Furthermore, was carried out in a boundary acoustic wave resonator of the comparative example, the signal terminal at a position shifted by 50μm in X ₂ side in the X direction from the center, the measurement of the impedance and phase by contacting a ground terminal. The results are shown in FIG. 17 together with the results when the signal terminal and the ground terminal are brought into contact with the centers of the first to third probe pads. In FIG. 17, three graphs are displayed as a single graph overlapping each other.

  As shown in FIG. 16, in the boundary acoustic wave resonator according to the comparative example, the measurement result changes greatly when the contact position of the probe pad is shifted in the Y direction. In such a boundary acoustic wave resonator, it can be seen that the measurement result does not change greatly even if the contact position of the probe pad is shifted in the Y direction. From this result, the drawing direction of the first wiring 13 from the first probe pad 16 and the drawing direction of the second and third wirings 14 and 15 from the second and third probe pads 17 and 18 are determined. It can be seen that the measurement variation due to the variation in the Y direction of the contact position of the probe pad can be reduced by reversing.

  As shown in FIGS. 15 and 17, when the contact position of the probe pad was shifted in the X direction, there was no substantial change in the measurement results in both the example and the comparative example. From this result, the drawing direction of the first wiring 13 from the first probe pad 16 and the drawing direction of the second and third wirings 14 and 15 from the second and third probe pads 17 and 18 are determined. When reversed, it was confirmed that the measurement variation due to the variation in the X-direction of the contact position of the probe pad did not substantially occur.

1 is a schematic plan view of a boundary acoustic wave resonator according to a first embodiment. However, the dielectric is not shown. It is the II-II arrow line view in FIG. It is an III-III arrow line view in FIG. The first to third wiring is a schematic plan view of the first to third probe boundary acoustic wave resonator drawn in X ₂ side from the pad. However, the dielectric is not shown. It is a schematic circuit diagram of a ladder type elastic wave filter provided with the boundary acoustic wave resonator of a 1st embodiment as a series arm resonator and a parallel arm resonator. It is a flowchart showing the manufacturing process of the boundary acoustic wave resonator in 1st Embodiment. It is a flowchart showing the manufacturing process of the boundary acoustic wave resonator in 2nd Embodiment. It is a schematic plan view showing a part of a piezoelectric wafer on which an IDT, first to third wirings, and first to third probe pads are formed. It is a flowchart showing the manufacturing process of the boundary acoustic wave resonator in 3rd Embodiment. It is a flowchart showing the manufacturing process of the boundary acoustic wave resonator in 4th Embodiment. It is a schematic plan view of the boundary acoustic wave resonator which concerns on a 1st modification. However, the dielectric is not shown. It is a schematic plan view of the boundary acoustic wave resonator which concerns on a 2nd modification. However, the dielectric is not shown. It is a schematic plan view of the boundary acoustic wave resonator which concerns on a 3rd modification. However, the dielectric is not shown. It is a graph showing the measurement result of the impedance and phase in the boundary acoustic wave resonator which concerns on an Example. It is a graph showing the measurement result of the impedance and phase in the boundary acoustic wave resonator which concerns on an Example. It is a graph showing the measurement result of the impedance and phase in the boundary acoustic wave resonator which concerns on a comparative example. It is a graph showing the measurement result of the impedance and phase in the boundary acoustic wave resonator which concerns on a comparative example. 6 is a schematic plan view of a bandpass filter disclosed in Patent Document 1. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Elastic boundary wave resonator 2 ... Ladder type | mold elastic wave filter 10 ... Piezoelectric body 10a ... Main surface 11 ... IDT
12a ... 1st grating reflector 12b ... 2nd grating reflector 13 ... 1st wiring 13a ... Connection part 14 ... 2nd wiring 14a ... Connection part 15 ... 3rd wiring 15a ... Connection part 16 ... 1st Probe pad 17 ... second probe pad 18 ... third probe pad 20 ... dielectric 20a-20c opening 21 ... comb electrode 21a ... bus bar 21b ... electrode finger 22 ... comb electrode 22a ... bus bar 22b ... electrode finger 30 ... Piezoelectric wafer

Claims (12)

A piezoelectric body;
An IDT formed on the piezoelectric body and having first and second comb electrodes interleaved with each other;
A first wiring formed on the piezoelectric body and electrically connected to the first comb electrode;
A second wiring formed on the piezoelectric body and electrically connected to the second comb electrode;
A first probe pad formed on the piezoelectric body and electrically connected to the first wiring;
A second probe pad formed on the piezoelectric body and electrically connected to the second wiring;
Both the first probe pad and the second probe pad are arranged on one side in the first direction with respect to the IDT,
The first wiring is drawn from the first probe pad to one side in a second direction perpendicular to the first direction, while the second wiring is drawn from the second probe pad to the first probe pad. A third wiring that is drawn out to the other side in the direction of 2 and formed on the piezoelectric body, and is electrically connected to the second comb electrode, and formed on the piezoelectric body. And a third probe pad electrically connected to the third wiring and disposed on one side in the first direction with respect to the IDT, wherein the third wiring An elastic wave device drawn out from the third probe pad to the other side in the second direction .   The elastic wave according to claim 1, wherein a direction in which the first wiring is drawn out from the first probe pad and a direction in which the second wiring is drawn out from the second probe pad are parallel to each other. apparatus.   The acoustic wave device according to claim 1 or 2, wherein the first probe pad and the second probe pad are arranged on an imaginary straight line extending in the second direction. The elastic wave device according to any one of claims 1 to 3, wherein the first probe pad is a signal-side probe pad, and the second and third probe pads are ground-side probe pads. The elastic wave device according to any one of claims 1 to 4 , wherein the first direction is a direction parallel to or perpendicular to a propagation direction of the elastic wave. The elastic wave device according to any one of claims 1 to 5 , further comprising a dielectric formed on the piezoelectric body so as to cover the IDT. A ladder-type elastic wave filter comprising the elastic wave device according to any one of claims 1 to 6 as at least one of a series arm elastic wave resonator and a parallel arm elastic wave resonator. It is a manufacturing method of the elastic wave device according to any one of claims 1 to 6 ,
Forming the IDT, the first and second wirings, and the first and second probe pads on the piezoelectric substrate;
A signal terminal of a frequency characteristic measuring device is connected to one of the first probe pad and the second probe pad, and the other of the first probe pad and the second probe pad is connected to a ground terminal. A method of manufacturing an acoustic wave device, comprising: a measurement step of measuring frequency characteristics by connecting to the device. It is a manufacturing method of the elastic wave device according to any one of claims 1 to 6 ,
Forming a plurality of sets of the IDT, the first and second wirings, and the first and second probe pads on a piezoelectric wafer formed of a piezoelectric material;
A signal terminal of a frequency characteristic measuring device is connected to one of the first probe pad and the second probe pad, and the other of the first probe pad and the second probe pad is connected to a ground terminal. And measuring a frequency characteristic of at least one of the plurality of sets of the IDT, the first and second wirings, and the first and second probe pads;
And a step of cutting the piezoelectric wafer into a plurality of the piezoelectric substrates. The measured measured frequency characteristics in the step further comprises the step of determining whether it is within a range of predetermined frequency characteristics, method for manufacturing the acoustic wave device according to claim 8 or 9. The IDT has a thickness that reduces a difference between a frequency characteristic of the elastic wave device according to the frequency characteristic measured in the measurement step and a predetermined frequency characteristic of the elastic wave device. The method for manufacturing an acoustic wave device according to any one of claims 8 to 10 , further comprising a step of reducing the thickness. A dielectric forming step that is performed prior to the measuring step and forms a dielectric so as to cover the IDT;
The dielectric material has a thickness that reduces a difference between a frequency characteristic of the elastic wave device corresponding to the frequency characteristic measured in the measurement step and a predetermined frequency characteristic of the elastic wave device. method of manufacturing thick further comprising the step of adjusting the acoustic wave device according to any one of claims 8-10.

Images