JP6935220B2 - Elastic wave elements, filters and multiplexers - Google Patents

Description

The present invention relates to elastic wave devices, filters and multiplexers, for example, elastic wave devices having comb-shaped electrodes, filters and multiplexers.

In a high-frequency communication system represented by a mobile phone, a high-frequency filter or the like is used to remove unnecessary signals other than the frequency band used for communication. An elastic wave element such as a surface acoustic wave (SAW) element is used for a high frequency filter or the like. In the SAW element, an IDT (Interdigital Transducer) having a plurality of electrode fingers is formed on a piezoelectric substrate. The IDT has a pair of comb-shaped electrodes having a plurality of electrode fingers and a bus bar. A ladder type filter (for example, Patent Document 1) is known as a high frequency filter using a surface acoustic wave element. Further, multiple mode filters such as a vertically coupled multiple mode filter are known (for example, Patent Document 2).

Japanese Unexamined Patent Publication No. 2004-146681 Japanese Unexamined Patent Publication No. 5-251988

One of the causes of the loss of the filter using the surface acoustic wave element is the resistance loss of the electrode finger. In order to reduce the resistance loss of the electrode finger, it is conceivable to use a metal having low resistance as the material for forming the electrode finger, to shorten the electrode finger, and to make the electrode finger thicker. However, these affect the characteristics of the filter. Therefore, it is difficult to arbitrarily design the material, length, and thickness of the electrode finger.

The present invention has been made in view of the above problems, and an object of the present invention is to reduce resistance loss.

The present invention comprises a first comb-shaped electrode including a piezoelectric layer, a plurality of first electrode fingers provided on the piezoelectric layer, and a first bus bar connected to the plurality of first electrode fingers. A plurality of second electrode fingers provided on the piezoelectric layer and at least a part thereof alternately provided in the arrangement direction of at least a part of the plurality of first electrode fingers and the plurality of first electrode fingers, and the plurality of first electrode fingers. The first bus bar in an intersecting region where a second comb-shaped electrode including a second bus bar connected to a two-electrode finger, and the plurality of first electrode fingers and the plurality of second electrode fingers overlap in the arrangement direction. A first connection electrode that connects the plurality of first electrode fingers to each other without the intervention of the second electrode finger, and a second connection electrode that connects the plurality of second electrode fingers to each other in the intersection region without the intervention of the second bus bar. The first wiring that electrically connects the first connection electrode and the first bus bar without the intervention of the plurality of first electrode fingers, and the second connection electrode without the intervention of the plurality of second electrode fingers. A second wiring for electrically connecting the second bus bar is provided, and the first connection electrode is an elastic wave element located closer to the second bus bar than the second connection electrode.

In the above configuration, the first connection electrode and the second connection electrode may be configured to extend in the intersection region in the arrangement direction.

In the above configuration, the first connecting electrode is connected to the plurality of first electrode fingers in the tip regions of the plurality of first electrode fingers, and the second connecting electrode is connected to the tip regions of the plurality of second electrode fingers. Can be configured to be connected to the plurality of second electrode fingers.

In the above configuration, the plurality of first electrode fingers and the insulating layer provided on the plurality of second electrode fingers are provided, and the first connecting electrode and the second connecting electrode are provided on the insulating layer. It can be configured as such.

In the above configuration, the plurality of first electrode fingers and the insulating layer provided on the plurality of second electrode fingers are provided, and the first connection electrode is the insulation of the tip region of the plurality of first electrode fingers. The insulating layer is provided on the layer and is connected to the plurality of first electrode fingers through the first opening provided in the insulating layer, and the second connecting electrode is the insulating layer in the tip region of the plurality of second electrode fingers. It can be configured to be provided above and connected to the plurality of second electrode fingers via a second opening provided in the insulating layer.

In the above configuration, the first connection electrode and the second connection electrode may be provided on the plurality of first electrode fingers and the plurality of second electrode fingers without passing through a gap.

In the above configuration, the intersecting region has a central region sandwiched between the tip regions of the plurality of first electrode fingers and the tip regions of the plurality of second electrode fingers, and the tip regions of the plurality of first electrode fingers and the tip regions of the plurality of first electrode fingers. The sound velocity of the elastic wave in the tip region of the plurality of second electrode fingers may be slower than the sound velocity of the elastic wave in the central region.

The present invention is a filter containing the elastic wave element as an IDT.

In the above configuration, the filter may be configured to be a multiple mode filter.

The present invention is a multiplexer including the above filter.

According to the present invention, resistance loss can be reduced.

FIG. 1 is a plan view of the filter according to the first embodiment. 2 (a) and 2 (b) are a cross-sectional view taken along the line AA and a cross-sectional view taken along the line BB of FIG. 3 (a) to 3 (c) are cross-sectional views taken along the line CC of FIG. 4 (a) to 4 (c) are cross-sectional views showing a method for manufacturing the filter according to the first embodiment, and FIGS. 4 (d) to 4 (f) are FIGS. 4 (a) to 4 (f), respectively. c) is a cross-sectional view taken along the line AA. 5 (a) to 5 (c) are cross-sectional views showing a method for manufacturing the filter according to the first embodiment, and FIGS. 5 (d) to 5 (f) are FIGS. 5 (a) to 5 (f), respectively. c) is a cross-sectional view taken along the line AA. FIG. 6A is a diagram showing the speed of sound of a surface acoustic wave in the Y direction of the surface acoustic wave element according to the first embodiment, and FIG. 6B is a cross-sectional view taken along the line EE of FIG. FIG. 7 is a plan view of the surface acoustic wave element according to the first modification of the first embodiment. FIG. 8 is a plan view of the surface acoustic wave element according to the second modification of the first embodiment. FIG. 9 is a cross-sectional view of the surface acoustic wave element according to the third modification of the first embodiment. FIG. 10A is a plan view of the surface acoustic wave element according to the second embodiment, and FIG. 10B is a circuit diagram of the filter using the second embodiment. FIG. 11 is a circuit diagram of the duplexer according to the first modification of the second embodiment.

Examples of the present invention will be described below with reference to the drawings.

FIG. 1 is a plan view of the filter according to the first embodiment. 2 (a) and 2 (b) are a cross-sectional view taken along the line AA and a cross-sectional view taken along the line BB of FIG. The arrangement direction of the electrode fingers 25a and 25b is the X direction, the stretching direction of the electrode fingers 25a and 25b is the Y direction, and the normal direction of the upper surface of the piezoelectric layer 10 is the Z direction. The X-direction, Y-direction, and Z-direction do not necessarily correspond to the X-axis direction, Y-axis direction, and Z-axis direction of the crystal orientation.

As shown in FIGS. 1 to 2 (b), the metal film 12 is formed on the piezoelectric layer 10. The metal film 12 forms the IDTs 31 to 33 and the reflector 34 arranged in the X direction. An insulating layer 14 is provided on the piezoelectric layer 10 so as to cover the IDTs 31 to 33 and the reflector 34. Connection electrodes 16a and 16b are provided on the insulating layer 14. The insulating layer 14 is provided with an opening 24. The connecting electrodes 16a (and 16b) and the plurality of electrode fingers 25a (and 25b) are connected via an opening.

IDTs 31 to 33 have a pair of comb-shaped electrodes 26a and 26b, respectively. The comb-shaped electrode 26a has a plurality of electrode fingers 25a and a bus bar 27a to which the plurality of electrode fingers 25a are connected. The comb-shaped electrode 26b has a plurality of electrode fingers 25b and a bus bar 27b to which the plurality of electrode fingers 25b are connected. The electrode fingers 25a and 25b are provided substantially alternately. The electrode fingers 25a and 25b mainly excite surface acoustic waves propagating in the X direction. The pitch λ of the electrode fingers 25a or 25b is approximately the wavelength of the surface acoustic wave. The region where the electrode fingers 25a and 25b overlap when viewed from the X direction is the intersection region 35. The tips of the electrode fingers 25a and 25b in the Y direction of the crossing region 35 are the tip regions 38a and 38b, respectively. The region between the tip regions 38a and 38b is the central region 36.

The connection electrode 16a includes the connection electrodes 21a, 22a and 23a, and the connection electrode 16b includes the connection electrodes 21b, 22b and 23b. The electrode fingers 25a of the IDTs 31, 32 and 33 are connected to the connecting electrodes 21a, 22a and 23a in the tip region 38a, respectively. The connection electrodes 21a, 22a and 23a are not connected to each other. The electrode fingers 25b of the IDTs 31, 32 and 33 are connected to the connecting electrodes 21b, 22b and 23b in the tip region 38b, respectively. The connection electrodes 21b, 22b and 23b are not connected to each other.

The input terminal Tin is electrically connected to the bus bar 27a of the IDT 32 and the connection electrode 22a via the wiring 18a. The bus bar 27b of the IDT 32 is electrically connected to the ground via the wiring 18b. The output terminal Tout is electrically connected to the bus bars 27b of the IDTs 31 and 33 and the connection electrodes 21b and 23b via the wiring 18c. The bus bar 27a of the IDT 31 is electrically connected to the ground via the wiring 18d. The connection electrode 21a is electrically connected to the ground via the wiring 18e. The bus bar 27a and the connection electrode 22b of the IDT 33 are electrically connected to the ground via the wiring 18f. The connection electrode 23a is electrically connected to the ground via the wiring 18g.

The piezoelectric layer 10 is, for example, a lithium tantalate substrate or a lithium niobate substrate. The piezoelectric layer 10 may be bonded on a sapphire substrate, an alumina substrate, a spinel substrate, or a silicon substrate. The metal film 12 is, for example, a copper film or an aluminum film (a film containing copper or aluminum as a main component). The metal film 12 may include a film of another metal below and / or above the copper film or the aluminum film. The insulating layer 14 is, for example, a silicon oxide film or a silicon nitride film. The connection electrodes 16a and 16b are, for example, a copper layer, a gold layer, an aluminum layer or a silver layer (a film containing copper, gold, aluminum or silver as a main component). The connecting electrodes 16a and 16b may include a film of another metal below and / or above a low resistance layer such as a copper layer, a gold layer, an aluminum layer or a silver layer. The input terminal Tin and the output terminal Tout are pads provided on the piezoelectric layer 10, for example. The input terminal Tin, the output terminal Tout, and the wirings 18a to 18g are metal layers such as a gold layer, a copper layer, or an aluminum layer.

In the vertically coupled double mode filter, the elastic waves excited by the three IDTs 31 to 33 are reflected by the reflector 34. As a result, the energy of the elastic wave is confined in IDT 31 to 33. A bandpass filter is formed by utilizing two vibration modes of primary and tertiary generated by acoustic coupling between IDT 31 and 33.

3 (a) to 3 (c) are cross-sectional views taken along the line CC of FIG. 3 (a) to 3 (c) show three types of examples of the cross-sectional shape of the filter in the first embodiment. As shown in FIG. 3A, the insulating layer 14 is thinner than the metal film 12. The upper surface of the insulating layer 14 is formed with irregularities corresponding to the irregularities of the metal film 12. The connection electrode 16a is connected to the electrode finger 25a through the opening 24 of the insulating layer 14. In FIG. 3A, the insulating layer 14 functions as a protective film such as IDT.

As shown in FIG. 3B, the insulating layer 14 is thicker than the metal film 12. The upper surface of the insulating layer 14 is flat. Other configurations are the same as those in FIG. 3 (a). In FIG. 3B, the insulating layer 14 functions as a temperature compensation film. The temperature coefficient of the elastic modulus of the insulating layer 14 is inversely the same as the temperature coefficient of the elastic modulus of the piezoelectric layer 10. For example, when the piezoelectric layer 10 is a lithium niobate substrate or a lithium tantalate substrate, a silicon oxide film (which may contain an element such as fluorine) is used as the insulating layer 14. As a result, the temperature coefficient of frequency can be brought close to zero.

As shown in FIG. 3C, the connection layer 17 is provided in the opening 24 of the insulating layer 14. The connecting layer 17 is a metal layer such as a gold layer, a copper layer or an aluminum layer. The connection electrode 16a is connected to the electrode finger 25a via the connection layer 17. Other configurations are the same as those in FIG. 3B, and the description thereof will be omitted. As shown in FIGS. 3A and 3B, the connection electrodes 16a and 16b may be directly connected to the electrode finger 25a. As shown in FIG. 3C, the connection electrodes 16a and 16b may be connected to the electrode finger 25a via the connection layer 17.

[Manufacturing method of Example 1]
The manufacturing method of Example 1 will be described by taking the cross-sectional structure of FIG. 3A as an example. 4 (a) to 4 (c) and 5 (a) to 5 (c) are cross-sectional views showing a method for manufacturing the filter according to the first embodiment, FIGS. 4 (d) to 4 (f). 5 (d) to 5 (f) are cross-sectional views taken along the line AA of FIGS. 4 (a) to 4 (c) and 5 (a) to 5 (c), respectively. 4 (a) to 4 (c) and 5 (a) to 5 (c) correspond to the range D of FIG.

As shown in FIGS. 4 (a) and 4 (d), the metal film 12 is formed on the piezoelectric layer 10. The metal film 12 is formed by, for example, a vapor deposition method and a lift-off method, or a sputtering method and an etching method. The metal film 12 forms the electrode fingers 25a and 25b. The electrode fingers 25a and 25b are provided alternately in the X direction. The insulating layer 14 is formed on the metal film 12. The insulating layer 14 is formed by, for example, a CVD (Chemical Vapor Deposition) method or a sputtering method. In the case of FIG. 3B, after the insulating layer 14 is formed thick, the upper surface of the insulating layer 14 is flattened by a CMP (Chemical Mechanical Polishing) method. In FIG. 4A, the metal film 12 is shown by a solid line through the insulating layer 14.

As shown in FIGS. 4 (b) and 4 (e), the mask layer 50 is formed on the piezoelectric layer 10 so as to cover the metal film 12 and the insulating layer 14. An opening 52 is provided in the mask layer 50 on the electrode finger 25a in the tip region 38a. No opening 52 is provided on the electrode finger 25b. The mask layer 50 is, for example, a photoresist, and the mask layer 50 having an opening 52 is formed by coating, exposing, and developing the photoresist. In FIG. 4B, the metal film 12 is shown by a broken line through the mask layer 50 and the insulating layer 14.

As shown in FIGS. 4 (c) and 4 (f), the mask layer 50 is used as a mask, and the insulating layer 14 in the opening 52 is removed by, for example, a dry etching method. If the insulating layer 14 is a silicon oxide film, using a fluorine-based gas CF ₄ system and the like as the etching gas. As a result, the opening 24 is formed in the insulating layer 14, and the upper surface of the electrode finger 25a is exposed from the opening 24.

As shown in FIGS. 5 (a) and 5 (d), the mask layer 50 is removed. As shown in FIGS. 5B and 5E, the mask layer 54 is formed on the piezoelectric layer 10 so as to cover the metal film 12 and the insulating layer 14. An opening 56 is provided in the mask layer 54 on the tip region 38a. The mask layer 54 is, for example, a photoresist, and the mask layer 54 having an opening 56 is formed by applying, exposing, and developing the photoresist. In FIG. 5B, the metal film 12 is shown by a broken line through the mask layer 54 and the insulating layer 14. In FIG. 5 (e), the mask layer 54 is not shown because it is a cross-sectional view taken along the line AA.

As shown in FIGS. 5 (c) and 5 (f), the connection electrodes 16a (and 16b) are formed in the opening 56 of the mask layer 54 and on the mask layer 54. The connection electrode 16a is formed by, for example, a vapor deposition method. At this time, the connection electrode 16a is formed along the unevenness of the upper surface of the insulating layer 14. For example, the vapor-deposited atoms are made to fly from a direction slightly inclined from the Z direction. By lifting off the mask layer 54, the mask layer 54 and the metal film on the mask layer 54 are removed. The connection electrode 16a may be formed by using a sputtering method and an etching method, or may be formed by using a plating method. The connection electrode 16a is preferably formed by a vapor deposition method and a lift-off method so as not to damage the insulating layer 14. As described above, the connection electrode 16a is formed in the tip region 38a. In FIG. 5C, the metal film 12 and the opening 24 are shown by broken lines through the connection electrode 16a and the insulating layer 14.

[Issues when no connection electrode is provided]
In an elastic surface wave element not provided with connecting electrodes 16a and 16b, in order to reduce the resistance loss of the electrode fingers 25a and 25b, the metal film 12 is a film mainly composed of copper or aluminum having low electrical resistance. It is conceivable to use an alloy film containing copper or aluminum or a laminated film containing these films or an alloy film. Further, in order to increase the cross-sectional area of the electrode fingers 25a and 25b, it is conceivable to thicken the metal film 12 and / or thicken the electrode fingers 25a and 25b. Further, it is conceivable to shorten the electrode fingers 25a and 25b.

The weight of the electrode fingers 25a and 25b affects the propagation of elastic waves as a mass effect. Therefore, it is difficult to arbitrarily design the material and film thickness of the electrode fingers 25a and 25b. Further, since the wavelength of the elastic wave corresponds to the pitch of the electrode fingers 25a and 25b, it is difficult to arbitrarily set the width of the electrode fingers 25a and 25b. Since the opening length (the length of the intersection region 35 in the Y direction) affects the impedance, it is difficult to arbitrarily design the lengths of the electrode fingers 25a and 25b. As described above, it is difficult to arbitrarily design the material and / or structure of the electrode fingers 25a and 25b. Therefore, it is difficult to reduce the resistance loss. In particular, as the frequency of the filter or the like becomes higher, the wavelength of the elastic wave becomes shorter, so that the electrode fingers 25a and 25b become thinner. Therefore, the resistance loss becomes large.

[Effect of Example 1]
According to the first embodiment, the comb-shaped electrode 26a (first comb-shaped electrode) includes a plurality of electrode fingers 25a (first electrode finger) and a bus bar 27a (with the first bus bar). The comb-shaped electrode 26b (second comb-shaped electrode) includes a plurality of electrode fingers 25b (second electrode finger) and a bus bar 27b (second bus bar). At least a part of the plurality of electrode fingers 25b is provided alternately with at least a part of the plurality of electrode fingers 25a in the X direction. The connection electrode 16a (first connection electrode) connects a plurality of electrode fingers 25a to each other in the intersecting region 35 without passing through the bus bar 27a. The connection electrode 16b (second connection electrode) connects a plurality of electrode fingers 25b to each other in the intersecting region 35 without passing through the bus bar 27b. Thereby, the resistance loss due to the electrode fingers 25a and 25b can be reduced.

The connection electrodes 16a and 16b extend in the crossing region 35 in the X direction. Thereby, the connection electrodes 16a and 16b can connect the electrode fingers 25a or 25b at a short distance.

The connection electrode 16a is connected to the plurality of electrode fingers 25a in the tip region 38a of the plurality of electrode fingers 25a. The connection electrode 16b is connected to the plurality of electrode fingers 25b in the tip region 38b of the plurality of electrode fingers 25b. Thereby, the resistance loss due to the electrode fingers 25a and 25b can be further reduced.

The insulating layer 14 is provided on the electrode fingers 25a and 25b, and the connecting electrodes 16a and 16b are provided on the insulating layer 14. Thereby, the connection electrodes 16a and 16b and the electrode fingers 25b and 25a can be electrically separated, respectively.

By including the surface acoustic wave element having the connection electrodes 16a and 16b as the IDT as in the first embodiment, the loss of the filter can be suppressed.

In a multiple mode filter such as a vertically coupled double mode filter, the logarithmic equation of IDT 31 to 33 is determined by the characteristics of the filter. The impedance of the filter seen from the input terminal Tin and the output terminal Tout is required to be a predetermined value (for example, 50Ω). Impedance is determined by the product of logarithmic and aperture length. Therefore, it is difficult to arbitrarily design the opening length (that is, the lengths of the electrode fingers 25a and 25b). Therefore, it is preferable to use the connection electrodes 16a and 16b in order to suppress the resistance loss.

[Piston mode structure]
This is an example of forming a piston mode structure using the connection electrodes 16a and 16b of the first embodiment. FIG. 6A is a diagram showing the speed of sound of a surface acoustic wave in the Y direction of the surface acoustic wave element according to the first embodiment, and FIG. 6B is a cross-sectional view taken along the line EE of FIG. As shown in FIGS. 6 (a) and 6 (b), on both sides of the intersecting region 35, the region between the electrode finger 25a and the bus bar 27b and the region between the electrode finger 25b and the bus bar 27a. , Is the gap region 37a. The area where the bus bars 27a and 27b are provided and the insulating layer 14 is provided is referred to as a bus bar area 37b.

As shown in FIG. 6A, the speed of sound in the gap region 37a is faster than the speed of sound in the intersection region 35. As a result, the elastic wave is confined in the intersecting region 35. In the tip regions 38a and 38b, connection electrodes 16a and 16b are provided on the insulating layer 14. As a result, the speed of sound of the elastic waves in the tip regions 38a and 38b becomes slower than the speed of sound in the central region 36. Therefore, the intensity distribution in the basic transverse mode in the intersection region 35 becomes flat in the Y direction. Further, the coupling coefficient of the higher-order transverse mode becomes smaller. As a result, a piston mode that suppresses transverse mode spurious can be realized.

An example of a surface acoustic wave element whose main mode is a Rayleigh wave used in the 800 MHz band is shown below as an example of materials and dimensions for realizing a piston mode.
Piezoelectric layer 10: 127.86 ° Y rotation X propagation Lithium niobate substrate electrode Finger pitch λ: 3.84 μm
Metal film 12: Copper layer insulating layer with a film thickness of 277 nm 14: Silicon oxide film connecting electrodes 16a and 16b with a film thickness of 1110 nm from the substrate
Width: 2.688 μm (0.7λ)
Weight per unit area: 3.888 x ^10-5 g / cm ²
The film thickness of the connection electrodes 16a and 16b can be calculated from the weight per unit area of the connection electrodes 16a and 16b and the density of the connection electrodes 16a and 16b. From the viewpoint of increasing the film thickness, aluminum having a low density is preferable. When the connection electrodes 16a and 16b are made of aluminum, the film thickness of the connection electrodes 16a and 16b is 144 nm.

As described above, according to the first embodiment, the connection electrode 16a is provided on the insulating layer 14 of the tip region 38a of the plurality of electrode fingers 25a, and is provided through the opening 24 (first opening) provided in the insulating layer 14. It is connected to a plurality of electrode fingers 25a. The connection electrode 16b is provided on the insulating layer 14 of the tip region 38b of the plurality of electrode fingers 25b, and is connected to the plurality of electrode fingers 25b via an opening 24 (second opening) provided in the insulating layer 14.

As a result, the sound velocity of the elastic waves in the tip regions 38a and 38b becomes slower than the sound velocity of the elastic waves in the central region 36. Therefore, a piston mode structure can be realized and transverse mode spurious can be suppressed.

The connecting electrodes 16a and 16b are provided on the plurality of electrode fingers 25a and 25b without passing through the gap. As a result, the weights of the connecting electrodes 16a and 16b are added to the electrode fingers 25a and 25b. Therefore, the piston mode can be realized.

In order to realize the piston mode, the width of the tip regions 38a and 38b in the Y direction is preferably 5λ or less, more preferably 2λ or less. The width of the tip regions 38a and 38b in the Y direction is preferably 0.1λ or more, more preferably 0.5λ or more.

[Modification 1 of Example 1]
FIG. 7 is a plan view of the surface acoustic wave element according to the first modification of the first embodiment. As shown in FIG. 7, the connection electrode 16a is provided in the gap region between the electrode finger 25a and the bus bar 27b and the region of the bus bar 27b in addition to the tip region 38a of the electrode finger 25a. The connection electrode 16b is provided in the gap region between the electrode finger 25b and the bus bar 27a and the region of the bus bar 27a in addition to the tip region 38b of the electrode finger 25b. Other configurations are the same as those in the first embodiment, and the description thereof will be omitted.

[Modification 2 of Example 1]
FIG. 8 is a plan view of the surface acoustic wave element according to the second modification of the first embodiment. As shown in FIG. 8, in addition to the connecting electrode 16a, the connecting electrode 16c is connected to the electrode finger 25a. In addition to the connecting electrode 16b, the connecting electrode 16d is connected to the electrode finger 25b. The connecting electrodes 16c and 16d are connected to the electrode fingers 25a and 25b in the central region 36, respectively. The connection electrodes 16a and 16c are electrically connected by a path different from that of the electrode fingers 25a. The connecting electrodes 16b and 16d are electrically connected by a path different from that of the electrode finger 25b. Other configurations are the same as those in the first embodiment, and the description thereof will be omitted.

As in the first modification of the first embodiment, the connection electrodes 16a and 16b may be provided in the gap region and the busbar region in addition to the tip regions 38a and 38b. Further, the connection electrodes 16c and 16d may be connected to the electrode fingers 25a and 25b in the central region 36 in addition to the tip regions 38a and 38b as in the modified example 2 of the first embodiment. As a result, the resistance of the connection electrodes 16a and 16b can be reduced, and the resistance loss can be further suppressed.

In the first embodiment and the first and second modifications thereof, the connection electrodes 16a and 16b are provided in the tip regions 38a and 38b, but may be provided in the central region 36.

[Modification 3 of Example 1]
FIG. 9 is a cross-sectional view of the surface acoustic wave element according to the third modification of the first embodiment, and corresponds to the CC cross section of FIG. As shown in FIG. 9, the width W1 of the opening 24 formed in the insulating layer 14 in the X direction is larger than the width W2 of the electrode finger 25a in the X direction. The connection electrode 16a is provided on the electrode finger 25a and the piezoelectric layer 10 in the opening 24. Other configurations are the same as those in the first embodiment, and the description thereof will be omitted.

When the widths of the electrode fingers 25a and 25b are narrowed, it becomes difficult to fit the opening 24 within the upper surfaces of the electrode fingers 25a and 25b. In such a case, the opening 24 may be wider than the electrode fingers 25a and 25b. When the connection electrode 16a is provided in contact with the piezoelectric layer 10 as shown in FIG. 9, the width of the electrode finger 25a becomes substantially large. If the length of the tip regions 38a and 38b in the Y direction is smaller than the opening length (the length of the intersection region 35 in the Y direction), the effect of thickening the electrode fingers 25a and 25b in the tip regions 38a and 38b is small.

FIG. 10A is a plan view of the surface acoustic wave element according to the second embodiment, and FIG. 10B is a circuit diagram of the filter using the second embodiment. As shown in FIG. 10 (a), the IDT 42 has a pair of comb-shaped electrodes 26a and 26b. The comb-shaped electrodes 26a and 26b are connected to terminals T1 and T2. Reflectors 44 are provided on both sides of the IDT 42 in the X direction. The connection electrode 16a connected to the electrode finger 25a is connected to the terminal T1 via the wiring 18a. The connection electrode 16b connected to the electrode finger 25b is connected to the terminal T2 via the wiring 18b. In this way, the 1-port resonator may be provided with the connection electrodes 16a and 16b connected to the electrode fingers 25a and 25b. Other configurations are the same as those in the first embodiment, and the description thereof will be omitted.

As shown in FIG. 10B, the series resonators S1 to S3 are connected in series between the input terminal Tin and the output terminal Tout, and the parallel resonators P1 and P2 are connected in parallel. By using surface acoustic wave elements similar to those of Example 1 and its modifications for the series resonators S1 to S3 and the parallel resonators P1 and P2, the loss of the ladder type filter can be reduced. The number of series resonators and parallel resonators can be set arbitrarily.

[Modification 1 of Example 2]
FIG. 11 is a circuit diagram of the duplexer according to the first modification of the second embodiment. As shown in FIG. 11, a transmission filter 40 is connected between the common terminal Ant and the transmission terminal Tx. A reception filter 42 is connected between the common terminal Ant and the reception terminal Rx. The transmission filter 40 passes a signal in the transmission band among the signals input from the transmission terminal Tx to the common terminal Ant as a transmission signal, and suppresses signals of other frequencies. The reception filter 42 passes a signal in the reception band among the signals input from the common terminal Ant to the reception terminal Rx as a reception signal, and suppresses signals of other frequencies. At least one of the transmission filter 40 and the reception filter 42 can be used as a filter for Examples 1 and 2 and a modification thereof. Although the duplexer has been described as an example as the multiplexer, a triplexer or a quadplexer may be used.

Although the examples of the present invention have been described in detail above, the present invention is not limited to such specific examples, and various modifications and modifications are made within the scope of the gist of the present invention described in the claims. It can be changed.

10 Hydraulic layer 12 Metal film 14 Insulation layer 16a-16d, 21a, 21b, 22a, 22b, 23a, 23b Connection electrode 18a-18g Wiring 24 Opening 25a, 25b Electrode finger 26a, 26b Comb electrode 27a, 27b Busbar 35 Crossing area 36 Central area 38a, 38b Tip area 40 Transmission filter 42 Reception filter

Claims (10)

Piezoelectric layer and
A first comb-shaped electrode provided on the piezoelectric layer and including a plurality of first electrode fingers and a first bus bar connected to the plurality of first electrode fingers.
A plurality of second electrode fingers provided on the piezoelectric layer, at least a part of which is provided alternately in the arrangement direction of at least a part of the plurality of first electrode fingers and the plurality of first electrode fingers, and the plurality of second electrode fingers. A second comb-shaped electrode, including a second bus bar connected to a second electrode finger,
A first connection electrode for connecting the plurality of first electrode fingers to each other without using the first bus bar in an intersecting region where the plurality of first electrode fingers and the plurality of second electrode fingers overlap in the arrangement direction.
In the intersecting region, the second connecting electrode for connecting the plurality of second electrode fingers to each other without passing through the second bus bar,
A first wiring that electrically connects the first connection electrode and the first bus bar without using the plurality of first electrode fingers.
A second wiring that electrically connects the second connection electrode and the second bus bar without using the plurality of second electrode fingers.
Equipped with
The first connection electrode is an elastic wave element located closer to the second bus bar than the second connection electrode. The elastic wave element according to claim 1, wherein the first connection electrode and the second connection electrode extend in the intersection region in the arrangement direction. The first connecting electrode is connected to the plurality of first electrode fingers in the tip region of the plurality of first electrode fingers.
The elastic wave element according to claim 1 or 2, wherein the second connection electrode is connected to the plurality of second electrode fingers in the tip region of the plurality of second electrode fingers. An insulating layer provided on the plurality of first electrode fingers and the plurality of second electrode fingers is provided.
The elastic wave element according to any one of claims 1 to 3, wherein the first connection electrode and the second connection electrode are provided on the insulating layer. An insulating layer provided on the plurality of first electrode fingers and the plurality of second electrode fingers is provided.
The first connection electrode is provided on the insulating layer in the tip region of the plurality of first electrode fingers, and is connected to the plurality of first electrode fingers through the first opening provided in the insulating layer.
The second connection electrode is provided on the insulating layer in the tip region of the plurality of second electrode fingers, and is connected to the plurality of second electrode fingers through the second opening provided in the insulating layer. Item 1. The elastic wave element according to item 1. The elastic wave element according to claim 5, wherein the first connection electrode and the second connection electrode are provided on the plurality of first electrode fingers and the plurality of second electrode fingers without passing through a gap. The intersecting region has a central region sandwiched between the tip regions of the plurality of first electrode fingers and the tip regions of the plurality of second electrode fingers, and the tip regions of the plurality of first electrode fingers and the plurality of first electrodes. 2. The elastic wave element according to any one of claims 3, 5 and 6, wherein the sound velocity of the elastic wave in the tip region of the two-electrode finger is slower than the sound velocity of the elastic wave in the central region. Filter including elastic wave device as IDT of any one of claims 1 or et 7. The filter according to claim 8, wherein the filter is a multiple mode filter. A multiplexer containing the filter of claim 8 or 9.

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