CN113810007A

CN113810007A - Surface acoustic wave resonator, filter and radio frequency front end device

Info

Publication number: CN113810007A
Application number: CN202111054657.2A
Authority: CN
Inventors: 韩兴; 周建
Original assignee: Changzhou Chengxin Semiconductor Co Ltd
Current assignee: Changzhou Chengxin Semiconductor Co Ltd
Priority date: 2021-09-08
Filing date: 2021-09-08
Publication date: 2021-12-17
Anticipated expiration: 2041-09-08
Also published as: WO2023036024A1; CN113810007B

Abstract

The embodiment of the invention provides a surface acoustic wave resonance device, a filtering device and a radio frequency front end device. A surface acoustic wave resonator device includes: a support layer; the piezoelectric layer is positioned above the supporting layer, the piezoelectric layer comprises a first side and a second side opposite to the first side, and the supporting layer is positioned at the first side; the reflecting medium layer is positioned on the first side, positioned above the supporting layer and embedded into the piezoelectric layer; an electrode layer on the second side on the piezoelectric layer; the reflecting medium layer comprises a first top part and a first side part, the first top part comprises a first concave-convex part, the first side part comprises a second concave-convex part, and the roughness of the second concave-convex part is greater than that of the first concave-convex part. The reflecting medium layer is arranged between the piezoelectric layer and the supporting layer and is embedded into the piezoelectric layer, the reflecting medium layer comprises irregular concave-convex parts, and bulk acoustic waves generated by the electrode layer are irregularly reflected at the irregular concave-convex parts, so that the bulk acoustic waves reflected to the upper surface of the piezoelectric layer can be reduced, and parasitic resonance is reduced.

Description

Surface acoustic wave resonator, filter and radio frequency front end device

Technical Field

The invention relates to the technical field of semiconductors, in particular to a surface acoustic wave resonance device, a filtering device and a radio frequency front-end device.

Background

A Radio Frequency (RF) front-end chip of a wireless communication device includes a power amplifier, an antenna switch, a Radio Frequency filter, a multiplexer, a low noise amplifier, and the like. The rf filter includes a piezoelectric Acoustic Surface Wave (SAW) filter, a Bulk Acoustic Wave (BAW) filter, a Micro-Electro-Mechanical System (MEMS) filter, an Integrated Passive Devices (IPD) filter, and the like.

Fig. 1 shows a SAW resonator 100 comprising: a substrate 110; a piezoelectric layer 130 disposed on the substrate 110, wherein the piezoelectric layer 130 includes a first side 131 and a second side 133 opposite to the first side 131, and the substrate 110 is disposed on the first side 131; and an electrode layer 150 on the second side 133 and on the piezoelectric layer 130, wherein the electrode layer 150 includes an InterDigital transducer (IDT), the IDT includes a plurality of electrode strips 151 and a plurality of electrode strips 153, the plurality of electrode strips 151 and the plurality of electrode strips 153 have different polarities, and the electrode strips 151 and the electrode strips 153 are alternately disposed. It should be noted that, when a voltage is applied between the electrode strips 151 and the electrode strips 153, in addition to exciting the surface acoustic wave (saw) propagating parallel to the piezoelectric layer 130, a bulk acoustic wave (bulk acoustic wave) is also generated and propagates in a direction perpendicular to the piezoelectric layer 130 (i.e., a direction corresponding to the thickness of the piezoelectric layer 130), as shown in fig. 1a, the bulk acoustic wave is reflected more regularly at the contact surface between the piezoelectric layer 130 and the substrate 110 (i.e., the reflection angle of the reflected wave is close, so that the reflection direction of the reflected wave is uniform), and the reflected bulk acoustic wave returns to the surface of the second side 133 to generate a parasitic resonance (spurious resonance). Referring to the reflection coefficient (S11) curve 170 in fig. 1b, the undulating section 171 of the curve 170 corresponds to the generated parasitic resonance, and the reflection coefficient of the undulating section 171 increases the insertion loss in the passband region of the SAW resonator.

Disclosure of Invention

The problem addressed by the present invention is to provide a surface acoustic wave resonator device that can reduce the volume acoustic waves reflected to the upper surface of the piezoelectric layer, thereby reducing parasitic resonances.

To solve the above problem, an embodiment of the present invention provides a surface acoustic wave resonator device, including: a support layer; a piezoelectric layer over the support layer, the piezoelectric layer including a first side and a second side opposite the first side, the support layer being located on the first side; the reflecting medium layer is positioned on the first side, positioned above the supporting layer and embedded into the piezoelectric layer; an electrode layer on the second side on the piezoelectric layer; the reflective medium layer includes a first top portion and a first side portion, the first top portion includes a first concave-convex portion, the first side portion includes a second concave-convex portion, and roughness of the second concave-convex portion is greater than roughness of the first concave-convex portion.

In some embodiments, the medium of the reflective medium layer comprises one of: vacuum, air. In some embodiments, the material of the reflective medium layer comprises at least one of: polymer, insulating dielectric, polysilicon.

In some embodiments, the electrode layer includes interdigital transducer devices located above the reflective medium layer, corresponding to the reflective medium layer.

In some embodiments, the first asperity has an arithmetical mean deviation in profile greater than 1 nm.

In some embodiments, the contour arithmetic mean deviation of the second concave-convex portion is greater than 2 nm.

In some embodiments, the support layer comprises a substrate. In some embodiments, the surface acoustic wave resonator device further comprises: and the connecting layer is positioned on the first side, is positioned between the substrate and the piezoelectric layer and is used for connecting the substrate and the piezoelectric layer, and the reflecting medium layer is positioned on the connecting layer or the connecting layer is positioned on two sides of the reflecting medium layer in the horizontal direction.

In some embodiments, the support layer further comprises: and the middle layer is positioned between the substrate and the piezoelectric layer and used for blocking leakage waves or temperature compensation, and the reflecting medium layer is positioned on the middle layer. In some embodiments, the material of the intermediate layer comprises at least one of: polymer, insulating dielectric, polysilicon.

It should be noted that, a reflecting medium layer is located between the piezoelectric layer and the substrate or the intermediate layer, and is embedded in the piezoelectric layer, the reflecting medium layer includes irregular concave-convex portions, and the bulk acoustic wave generated by the electrode layer generates irregular reflection (i.e., the reflection direction of the reflected wave is not uniform) at the irregular concave-convex portions, so that the bulk acoustic wave reflected to the upper surface of the piezoelectric layer can be reduced, and thus the parasitic resonance is reduced.

In addition, the roughness of the side portions of the reflective medium layer is larger than that of the top portion thereof, so that the degree of irregularity in reflection can be further improved.

The embodiment of the present invention further provides a filtering apparatus, including but not limited to: at least one of the above embodiments provides a surface acoustic wave resonator device.

The embodiment of the present invention further provides a radio frequency front end device, including but not limited to: the power amplifying device and at least one filtering device provided by the above embodiment; the power amplifying device is connected with the filtering device.

The embodiment of the present invention further provides a radio frequency front end device, including but not limited to: the low noise amplifying device and at least one filtering device provided by the above embodiment; the low-noise amplifying device is connected with the filtering device.

The embodiment of the present invention further provides a radio frequency front end device, including but not limited to: the multiplexing device comprises at least one filtering device provided by the above embodiment.

Drawings

FIG. 1a is a cross-sectional A schematic diagram of a SAW resonator 100;

FIG. 1b is a graphical representation of the reflectance (S11) curve for a SAW resonator;

FIG. 2 is a cross-sectional A schematic view of a SAW resonator device 200 in accordance with an embodiment of the present invention;

FIG. 3 is a cross-sectional A schematic diagram of a SAW resonator device 300 in accordance with an embodiment of the present invention;

FIG. 4 is a cross-sectional A schematic view of a SAW resonator device 400 in accordance with an embodiment of the present invention;

FIG. 5 is a cross-sectional A schematic view of a SAW resonator device 500 in accordance with an embodiment of the present invention;

fig. 6 is a schematic structural diagram of a SAW filter device 600 according to an embodiment of the present invention in a cross section a;

fig. 7 is a schematic cross-sectional view a of a SAW filter device 700 according to an embodiment of the present invention.

Detailed Description

In order to make the aforementioned objects, features and advantages of the present invention comprehensible, embodiments accompanied with figures are described in detail below.

In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention, but the present invention may be practiced in other ways than those specifically described herein, and thus the present invention is not limited to the specific embodiments disclosed below.

As described in the background section, applying a voltage between two adjacent electrode strips, in addition to exciting surface acoustic waves, also generates bulk acoustic waves, which propagate in a direction perpendicular to the piezoelectric layer (i.e., a direction corresponding to the thickness of the piezoelectric layer), and the bulk acoustic waves are reflected more regularly at the contact surface of the piezoelectric layer and the substrate, and the reflected bulk acoustic waves are transmitted back to the upper surface of the piezoelectric layer to generate parasitic resonance, thereby increasing the insertion loss in the pass band region of the SAW resonator.

The inventors of the present invention have found that by providing a reflective medium layer, which is interposed between a piezoelectric layer and a base or an intermediate layer, embedding the piezoelectric layer, the reflective medium layer includes irregular concave-convex portions where a bulk acoustic wave generated by an electrode layer is irregularly reflected, the bulk acoustic wave reflected to the upper surface of the piezoelectric layer can be reduced, and thus parasitic resonance can be reduced.

The inventors of the present invention have also found that the roughness of the side portions of the reflective medium layer is larger than that of the top portion thereof to further improve the degree of irregularity of reflection.

An embodiment of the present invention provides a surface acoustic wave resonator device, including: a support layer; a piezoelectric layer over the support layer, the piezoelectric layer including a first side and a second side opposite the first side, the support layer being located on the first side; the reflecting medium layer is positioned on the first side, positioned above the supporting layer and embedded into the piezoelectric layer; an electrode layer on the second side on the piezoelectric layer; the reflective medium layer includes a first top portion and a first side portion, the first top portion includes a first concave-convex portion, the first side portion includes a second concave-convex portion, and roughness of the second concave-convex portion is greater than roughness of the first concave-convex portion.

In some embodiments, the medium of the reflective medium layer includes, but is not limited to, one of: vacuum, air.

In some embodiments, the material of the reflective medium layer includes, but is not limited to, at least one of: polymer, insulating dielectric, polysilicon.

In some embodiments, the support layer further comprises: and the middle layer is positioned between the substrate and the piezoelectric layer and used for blocking leakage waves or temperature compensation, and the reflecting medium layer is positioned on the middle layer. In some embodiments, the material of the intermediate layer includes, but is not limited to, at least one of: polymer, insulating dielectric, polysilicon.

Fig. 2 through 5 show 4 embodiments of the saw resonator device of the present invention, which 4 embodiments employ resonator devices of different structures, but the present invention can also be implemented in other ways than those described herein, and thus the present invention is not limited to the embodiments disclosed below.

Fig. 2 is a cross-sectional a structural diagram of a SAW resonator device 200 according to an embodiment of the present invention.

As shown in fig. 2, an embodiment of the present invention provides a SAW resonator device 200, including: a substrate 210; a reflective dielectric layer 230 over the substrate 210; a piezoelectric layer 250 disposed above the substrate 210, wherein the piezoelectric layer 250 includes a first side 251 and a second side 253 opposite to the first side 251, the substrate 210 is disposed on the first side 251, the reflective medium layer 230 is disposed on the first side 251, and the piezoelectric layer 250 is embedded therein; and an electrode layer 270 on the second side 253 and on the piezoelectric layer 250, the electrode layer 270 being above the reflective medium layer 230; the reflective medium layer 230 includes a top portion 231 and a side portion 233, wherein the top portion 231 includes irregular concave-convex portions, and the side portion 233 includes irregular concave-convex portions.

It should be noted that, as shown in fig. 2, applying a voltage to the electrode layer 270 generates a bulk acoustic wave, and the bulk acoustic wave propagates to the irregular concave-convex portion of the top 231 or the side 233 along a direction perpendicular to the piezoelectric layer 250 to generate irregular reflection, so that the bulk acoustic wave reflected back to the surface of the second side 253 is reduced, and thus the parasitic resonance is reduced. Referring again to the reflection coefficient (S11) curve 190 in fig. 1b, the undulating segment 191 of the curve 190 corresponds to a reduced spurious resonance, and as compared to the undulating segment 171 and the undulating segment 191, the reduced spurious resonance results in a reduced amplitude of the undulating segment, thereby reducing the insertion loss in the passband region of the SAW resonator device. It should be noted that fig. 1b is only schematic and is used for more intuitively understanding the advantages of the embodiment of the present invention, but not for equalizing the actual performance of the SAW resonator device of the embodiment of the present invention.

In this embodiment, the material of the substrate 210 includes, but is not limited to, at least one of the following: silicon, silicon carbide, silicon dioxide, gallium arsenide, gallium nitride, sapphire, spinel, ceramics, polymers. In this embodiment, the polymer includes, but is not limited to, at least one of: benzocyclobutene (i.e., BCB), photosensitive epoxy photoresist (e.g., SU-8), polyimide.

In this embodiment, the medium of the reflective medium layer 230 includes, but is not limited to, one of the following: vacuum, air.

In this embodiment, the piezoelectric layer 250 is disposed on the left and right sides of the reflective medium layer 230, that is, on the two sides in the horizontal direction, the substrate 210 is disposed on the lower side of the reflective medium layer 230, and the piezoelectric layer 250 is disposed on the upper side of the reflective medium layer 230, that is, the substrate 210 and the piezoelectric layer 250 are disposed on the two sides in the vertical direction of the reflective medium layer 230, respectively.

In this embodiment, the material of the piezoelectric layer 250 includes, but is not limited to, at least one of the following: aluminum nitride, aluminum oxide alloy, gallium nitride, zinc oxide, lithium tantalate, lithium niobate, lead zirconate titanate, lead magnesium niobate-lead titanate.

In this embodiment, the electrode layer 270 includes an interdigital transducer (IDT), and the IDT includes a plurality of first electrode stripes and a plurality of second electrode stripes corresponding to the reflective medium layer 230, wherein the polarities of the first electrode stripes and the second electrode stripes are different, and the first electrode stripes and the second electrode stripes are alternately disposed. It should be noted that the IDT structure in the embodiment of the present invention is a specific embodiment, and the present invention may also be implemented by other IDT structures different from those described herein, so that the present invention is not limited by the specific embodiment, and other IDT structures known to those skilled in the art may be applied to the embodiment of the present invention.

In this embodiment, the roughness of the side portions 233 is greater than the roughness of the top portion 231 for further improving the irregularity of the reflection. In this embodiment, the arithmetic mean deviation of the profile of the irregular concave-convex portion of the top 231 is greater than 1 nm. In this embodiment, the average deviation of the contour counts of the irregular concave-convex portions of the side portions 233 is greater than 2 nm. It should be noted that the arithmetic mean deviation of the profile refers to the arithmetic mean of the absolute values of the profile offsets in the sampling length, and is used to indicate the surface roughness.

In another embodiment, the SAW resonator device further comprises a connecting layer between the substrate and the piezoelectric layer for bonding or bonding the substrate and the piezoelectric layer, wherein the material of the connecting layer includes but is not limited to at least one of: polymer, insulating dielectric, polysilicon. Wherein the polymer includes, but is not limited to, at least one of: benzocyclobutene (i.e., BCB), photosensitive epoxy photoresist (e.g., SU-8), polyimide. The insulating dielectric includes, but is not limited to, at least one of: aluminum nitride, silicon dioxide, silicon nitride, titanium oxide.

Fig. 3 is a sectional a structural diagram of a SAW resonator device 300 according to an embodiment of the present invention.

As shown in fig. 3, an embodiment of the present invention provides a SAW resonator device 300 including: a substrate 310; a connection layer 320 on the substrate 310; a reflective dielectric layer 330 over the substrate 310; a piezoelectric layer 340 disposed on the connection layer 320, wherein the piezoelectric layer 340 includes a first side 341 and a second side 343 opposite to the first side 341, the substrate 310 is disposed on the first side 341, the connection layer 320 is disposed on the first side 341, the reflective medium layer 330 is disposed on the first side 341 and embedded in the piezoelectric layer 340, and the connection layer 320 is disposed on the left and right sides (i.e., two sides in the horizontal direction) of the reflective medium layer 330 and used for bonding or bonding the substrate 310 and the piezoelectric layer 340; an electrode layer 350 on the second side 343 and on the piezoelectric layer 340, the electrode layer 350 being above the reflective medium layer 330; and a temperature compensation layer 360 on the second side 343, on the piezoelectric layer 340, covering the electrode layer 350; the reflective medium layer 330 includes a top portion 331 and side portions 333, wherein the top portion 331 includes irregular asperities, and the side portions 333 includes irregular asperities.

It should be noted that, when a voltage is applied to the electrode layer 350, a bulk acoustic wave is generated, and the bulk acoustic wave propagates to the irregular concave-convex portion of the top portion 331 or the side portion 333 in a direction perpendicular to the piezoelectric layer 340, so that irregular reflection is generated, and the bulk acoustic wave reflected back to the surface of the second side 343 is reduced, thereby reducing parasitic resonance.

In this embodiment, the material of the substrate 310 includes, but is not limited to, at least one of the following: silicon, silicon carbide, silicon dioxide, gallium arsenide, gallium nitride, sapphire, spinel, ceramics, polymers. In this embodiment, the polymer includes, but is not limited to, at least one of: benzocyclobutene (i.e., BCB), photosensitive epoxy photoresist (e.g., SU-8), polyimide.

In this embodiment, the connecting layer 320 is located between the substrate 310 and the piezoelectric layer 340 in the vertical direction. In this embodiment, the material of the connection layer 320 includes, but is not limited to, at least one of the following: polymer, insulating dielectric, polysilicon. In this embodiment, the polymer includes, but is not limited to, at least one of: benzocyclobutene (i.e., BCB), photosensitive epoxy photoresist (e.g., SU-8), polyimide. In this embodiment, the insulating dielectric includes, but is not limited to, at least one of: aluminum nitride, silicon dioxide, silicon nitride, titanium oxide.

In this embodiment, the medium of the reflective medium layer 330 includes, but is not limited to, one of the following: vacuum, air.

In this embodiment, the left and right sides of the reflective medium layer 330, i.e., the two sides in the horizontal direction, are the connecting layer 320 and the piezoelectric layer 340 located on the connecting layer 320, the lower side of the reflective medium layer 330 is the substrate 310, and the upper side of the reflective medium layer 330 is the piezoelectric layer 340, i.e., the two sides in the vertical direction of the reflective medium layer 330 are the substrate 310 and the piezoelectric layer 340, respectively.

In this embodiment, the material of the piezoelectric layer 340 includes, but is not limited to, at least one of the following: aluminum nitride, aluminum oxide alloy, gallium nitride, zinc oxide, lithium tantalate, lithium niobate, lead zirconate titanate, lead magnesium niobate-lead titanate.

In this embodiment, the electrode layer 350 includes an interdigital transducer (IDT) corresponding to the reflective medium layer 330, and the IDT includes a plurality of first electrode stripes and a plurality of second electrode stripes, wherein the polarities of the first electrode stripes and the second electrode stripes are different, and the first electrode stripes and the second electrode stripes are alternately disposed. It should be noted that the IDT structure in the embodiment of the present invention is a specific embodiment, and the present invention may also be implemented by other IDT structures different from those described herein, so that the present invention is not limited by the specific embodiment, and other IDT structures known to those skilled in the art may be applied to the embodiment of the present invention.

It should be noted that the material of the Temperature compensation layer 360 (e.g., silicon dioxide) and the material of the piezoelectric layer 340 have opposite Temperature Frequency shift characteristics, so that the Temperature Coefficient of Frequency (TCF) of the resonant device tends to be 0 ppm/degree c, thereby improving the Frequency-Temperature stability.

In this embodiment, the roughness of the side portions 333 is larger than that of the top portion 331 for further improving the irregularity of the reflection. In this embodiment, the average deviation of the contour number of the irregular concave-convex portion of the top portion 331 is greater than 1 nm. In this embodiment, the average deviation of the contour number of the irregular concave-convex portions of the side portions 333 is greater than 2 nm. It should be noted that the arithmetic mean deviation of the profile refers to the arithmetic mean of the absolute values of the profile offsets in the sampling length, and is used to indicate the surface roughness.

As shown in fig. 4, an embodiment of the present invention provides a SAW resonating device 400 including: a substrate 410; a connection layer 430 on the substrate 410; a reflective dielectric layer 450 on the connection layer 430; a piezoelectric layer 470 on the connection layer 430, wherein the piezoelectric layer 470 includes a first side 471 and a second side 473 opposite to the first side 471, the substrate 410 is located at the first side 471, the connection layer 430 is located at the first side 471, and the reflective medium layer 450 is located at the first side 471 and embedded in the piezoelectric layer 470; and an electrode layer 490 on the second side 473 on the piezoelectric layer 470, the electrode layer 490 being over the reflective dielectric layer 450; the reflective medium layer 450 includes a top portion 451 and a side portion 453, and the top portion 451 includes irregular asperities.

It should be noted that, when a voltage is applied to the electrode layer 490, a bulk acoustic wave is generated, and the bulk acoustic wave propagates to the irregular rugged portion of the top portion 451 in a direction perpendicular to the piezoelectric layer 470, so that irregular reflection is generated, and the bulk acoustic wave reflected back to the surface of the second side 473 is reduced, thereby reducing parasitic resonance.

In this embodiment, the material of the substrate 410 includes, but is not limited to, at least one of the following: silicon, silicon carbide, silicon dioxide, gallium arsenide, gallium nitride, sapphire, spinel, ceramics, polymers. In this embodiment, the polymer includes, but is not limited to, at least one of: benzocyclobutene (i.e., BCB), photosensitive epoxy photoresist (e.g., SU-8), polyimide.

In this embodiment, the connecting layer 430 is located between the substrate 410 and the piezoelectric layer 470 in the vertical direction. In this embodiment, the material of the connection layer 430 includes, but is not limited to, at least one of the following: polymer, insulating dielectric, polysilicon. In this embodiment, the polymer includes, but is not limited to, at least one of: benzocyclobutene (i.e., BCB), photosensitive epoxy photoresist (e.g., SU-8), polyimide. In this embodiment, the insulating dielectric includes, but is not limited to, at least one of: aluminum nitride, silicon dioxide, silicon nitride, titanium oxide.

In this embodiment, the material of the reflective medium layer 450 includes, but is not limited to, at least one of the following: polymer, insulating dielectric, polysilicon. In this embodiment, the polymer includes, but is not limited to, at least one of: benzocyclobutene (i.e., BCB), photosensitive epoxy photoresist (e.g., SU-8), polyimide. In this embodiment, the insulating dielectric includes, but is not limited to, at least one of: aluminum nitride, silicon dioxide, silicon nitride, titanium oxide.

In this embodiment, the material of the reflective medium layer 450 is different from the material of the connection layer 430. In another embodiment, the material of the reflective medium layer and the material of the connection layer may be the same. It should be noted that filling the reflective medium layer can enhance the connection strength between the substrate and the piezoelectric layer.

In another embodiment, the medium of the reflective medium layer includes, but is not limited to, one of the following: vacuum, air.

In this embodiment, the left and right sides of the reflective medium layer 450, i.e., the two sides in the horizontal direction, are the piezoelectric layer 470, the lower side of the reflective medium layer 450 is the connecting layer 430, and the upper side of the reflective medium layer 450 is the piezoelectric layer 470, i.e., the two sides in the vertical direction of the reflective medium layer 450 are the connecting layer 430 and the piezoelectric layer 470, respectively.

In this embodiment, the material of the piezoelectric layer 470 includes, but is not limited to, at least one of the following: aluminum nitride, aluminum oxide alloy, gallium nitride, zinc oxide, lithium tantalate, lithium niobate, lead zirconate titanate, lead magnesium niobate-lead titanate.

In this embodiment, the electrode layer 490 includes an interdigital transducer device (IDT), and the IDT includes a plurality of first electrode stripes and a plurality of second electrode stripes corresponding to the reflective medium layer 450, wherein the polarities of the plurality of first electrode stripes and the plurality of second electrode stripes are different, and the first electrode stripes and the second electrode stripes are alternately disposed. It should be noted that the IDT structure in the embodiment of the present invention is a specific embodiment, and the present invention may also be implemented by other IDT structures different from those described herein, so that the present invention is not limited by the specific embodiment, and other IDT structures known to those skilled in the art may be applied to the embodiment of the present invention.

In this embodiment, the arithmetic mean deviation of the profile of the irregular concave-convex portion of the top portion 451 is greater than 1 nm. It should be noted that the arithmetic mean deviation of the profile refers to the arithmetic mean of the absolute values of the profile offsets in the sampling length, and is used to indicate the surface roughness.

Fig. 5 is a schematic structural diagram of a SAW resonator device 500 according to an embodiment of the present invention.

As shown in fig. 5, an embodiment of the present invention provides a SAW resonator device 500, including: a substrate 510; an intermediate layer 530 on the substrate 510 for blocking leakage waves or temperature compensation; a reflective dielectric layer 550 on the intermediate layer 530; a piezoelectric layer 570 disposed on the middle layer 530, the piezoelectric layer 570 including a first side 571 and a second side 573 opposite to the first side 571, the substrate 510 being disposed on the first side 571, the middle layer 530 being disposed on the first side 571, the reflective medium layer 550 being disposed on the first side 571, the piezoelectric layer 570 being embedded therein; and an electrode layer 590 on the second side 573 on the piezoelectric layer 570, the electrode layer 590 being over the reflective medium layer 550; the reflective medium layer 550 includes a top portion 551 and side portions 553, the top portion 551 includes irregular asperities, and the side portions 553 includes irregular asperities.

It should be noted that, when a voltage is applied to the electrode layer 590, a bulk acoustic wave is generated, and the bulk acoustic wave propagates to the irregular rugged portion of the top portion 551 or the side portion 553 in a direction perpendicular to the piezoelectric layer 570, so that irregular reflection is generated, and the bulk acoustic wave reflected back to the surface of the second side 573 is reduced, thereby reducing parasitic resonance.

In this embodiment, the material of the substrate 510 includes, but is not limited to, at least one of the following: silicon, silicon carbide, silicon dioxide, gallium arsenide, gallium nitride, sapphire, spinel, ceramics, polymers. In this embodiment, the polymer includes, but is not limited to, at least one of: benzocyclobutene (i.e., BCB), photosensitive epoxy photoresist (e.g., SU-8), polyimide.

In this embodiment, the material of the intermediate layer 530 includes, but is not limited to, at least one of the following: polymer, insulating dielectric, polysilicon. In this embodiment, the polymer includes, but is not limited to, at least one of: benzocyclobutene (i.e., BCB), photosensitive epoxy photoresist (e.g., SU-8), polyimide. In this embodiment, the insulating dielectric includes, but is not limited to, at least one of: aluminum nitride, silicon dioxide, silicon nitride, titanium oxide.

In this embodiment, the material of the reflective medium layer 550 includes, but is not limited to, at least one of the following: polymer, insulating dielectric, polysilicon. In this embodiment, the polymer includes, but is not limited to, at least one of: benzocyclobutene (i.e., BCB), photosensitive epoxy photoresist (e.g., SU-8), polyimide. In this embodiment, the insulating dielectric includes, but is not limited to, at least one of: aluminum nitride, silicon dioxide, silicon nitride, titanium oxide.

In this embodiment, the material of the reflective medium layer 550 is different from that of the intermediate layer 530. In another embodiment, the material of the reflective medium layer and the material of the intermediate layer may be the same. It should be noted that filling the reflective medium layer can enhance the connection strength between the intermediate layer and the piezoelectric layer.

In this embodiment, the left and right sides of the reflective medium layer 550, i.e., the two sides in the horizontal direction, are the piezoelectric layers 570, the lower side of the reflective medium layer 550 is the middle layer 530, and the upper side of the reflective medium layer 550 is the piezoelectric layers 570, i.e., the two sides in the vertical direction of the reflective medium layer 550 are the middle layer 530 and the piezoelectric layers 570, respectively.

In this embodiment, the material of the piezoelectric layer 570 includes, but is not limited to, at least one of the following: aluminum nitride, aluminum oxide alloy, gallium nitride, zinc oxide, lithium tantalate, lithium niobate, lead zirconate titanate, lead magnesium niobate-lead titanate. It should be noted that the acoustic impedance of the material of the intermediate layer 530 is different from the acoustic impedance of the material of the piezoelectric layer 570, so as to block the leakage wave. Furthermore, if the material of the intermediate layer 530 (e.g., silicon dioxide) and the material of the piezoelectric layer 570 have opposite temperature-frequency shifting characteristics, the TCF of the resonator device can be reduced towards 0 ppm/deg.C, thereby improving frequency-temperature stability, i.e., the intermediate layer 530 is a temperature compensation layer.

In this embodiment, the electrode layer 590 includes an interdigital transducer device (IDT), and the IDT includes a plurality of first electrode stripes and a plurality of second electrode stripes corresponding to the reflective medium layer 550, wherein the polarities of the plurality of first electrode stripes and the plurality of second electrode stripes are different, and the first electrode stripes and the second electrode stripes are alternately disposed. It should be noted that the IDT structure in the embodiment of the present invention is a specific embodiment, and the present invention may also be implemented by other IDT structures different from those described herein, so that the present invention is not limited by the specific embodiment, and other IDT structures known to those skilled in the art may be applied to the embodiment of the present invention.

In this embodiment, the roughness of the side portions 553 is greater than that of the top portion 551 for further enhancing the irregularity degree of reflection. In this embodiment, the average deviation of the contour number of the irregular concave-convex portion of the top portion 551 is greater than 1 nm. In this embodiment, the average deviation of the contour of the irregular uneven portion of the side portion 553 is greater than 2 nm. It should be noted that the arithmetic mean deviation of the profile refers to the arithmetic mean of the absolute values of the profile offsets in the sampling length, and is used to indicate the surface roughness.

In this embodiment, the SAW resonator device 500 further includes: and a connection layer 520 between the substrate 510 and the intermediate layer 530 for bonding the substrate 510 and the intermediate layer 530. In this embodiment, the material of the connection layer 520 includes, but is not limited to, at least one of the following: polymer, insulating dielectric, polysilicon. In this embodiment, the polymer includes, but is not limited to, at least one of: benzocyclobutene (i.e., BCB), photosensitive epoxy photoresist (e.g., SU-8), polyimide. In this embodiment, the insulating dielectric includes, but is not limited to, at least one of: aluminum nitride, silicon dioxide, silicon nitride, titanium oxide.

Fig. 6 and 7 show 2 embodiments of the filtering apparatus according to the present invention, and the 2 embodiments adopt filtering apparatuses with different structures, but the present invention can also be implemented in other ways different from those described herein, and therefore the present invention is not limited by the embodiments disclosed below.

Fig. 6 is a schematic cross-sectional view a of a SAW filter device 600 according to an embodiment of the present invention.

As shown in fig. 6, an embodiment of the present invention provides a SAW filter device 600, including: a substrate 610; a connection layer 630 on the substrate 610; a plurality of reflective dielectric layers 650 on the connection layer 630, the plurality of reflective dielectric layers 650 including a reflective dielectric layer 651, a reflective dielectric layer 653, a reflective dielectric layer 655, and a reflective dielectric layer 657; a piezoelectric layer 670 disposed on the connection layer 630, wherein the piezoelectric layer 670 includes a first side 671 and a second side 673 opposite to the first side 671, the substrate 610 is disposed on the first side 671, the connection layer 630 is disposed on the first side 671, and the plurality of reflective medium layers 650 are disposed on the first side 671 and embedded in the piezoelectric layer 670; and an electrode layer 690 positioned on the second side 673 and on the piezoelectric layer 670, the electrode layer 690 including an IDT 691, an IDT 693, an IDT 695 and an IDT 697, the IDT 691 being positioned above the reflective dielectric layer 651 and corresponding to the reflective dielectric layer 651; the IDT 693 is positioned above the reflecting medium layer 653 and corresponds to the reflecting medium layer 653; the IDT 695 is located above the reflective dielectric layer 655 and corresponds to the reflective dielectric layer 655; the IDT 697 is located above the reflective medium layer 657 and corresponds to the reflective medium layer 657; wherein the reflective medium layer 651 includes a first top portion including an irregular rugged portion and a first side portion; the reflective medium layer 653 includes a second top portion including irregular asperities and a second side portion; the reflective medium layer 655 includes a third top portion and a third side portion, the third top portion including an irregular concave-convex portion; the reflective medium layer 657 includes a fourth top portion including an irregular rugged portion and a fourth side portion.

It should be noted that, when a voltage is applied to the electrode layer 690, a bulk acoustic wave is generated, and the bulk acoustic wave propagates to the irregular concave-convex portions of the plurality of reflective medium layers 650 in a direction perpendicular to the piezoelectric layer 670, so that irregular reflection is generated, and the bulk acoustic wave reflected back to the surface of the second side 673 is reduced, thereby reducing parasitic resonance.

In this embodiment, the material of the substrate 610 includes, but is not limited to, at least one of the following: silicon, silicon carbide, silicon dioxide, gallium arsenide, gallium nitride, sapphire, spinel, ceramics, polymers. In this embodiment, the polymer includes, but is not limited to, at least one of: benzocyclobutene (i.e., BCB), photosensitive epoxy photoresist (e.g., SU-8), polyimide.

In this embodiment, the connection layer 630 is disposed between the substrate 610 and the plurality of reflective medium layers 650 in the vertical direction. In this embodiment, the material of the connection layer 630 includes, but is not limited to, at least one of the following: polymer, insulating dielectric, polysilicon. In this embodiment, the polymer includes, but is not limited to, at least one of: benzocyclobutene (i.e., BCB), photosensitive epoxy photoresist (e.g., SU-8), polyimide. In this embodiment, the insulating dielectric includes, but is not limited to, at least one of: aluminum nitride, silicon dioxide, silicon nitride, titanium oxide.

In this embodiment, the material of the plurality of reflective medium layers 650 includes, but is not limited to, at least one of the following: polymer, insulating dielectric, polysilicon. In this embodiment, the polymer includes, but is not limited to, at least one of: benzocyclobutene (i.e., BCB), photosensitive epoxy photoresist (e.g., SU-8), polyimide. In this embodiment, the insulating dielectric includes, but is not limited to, at least one of: aluminum nitride, silicon dioxide, silicon nitride, titanium oxide.

In this embodiment, the material of the plurality of reflective medium layers 650 is different from the material of the connection layer 630. In another embodiment, the material of the plurality of reflective medium layers and the material of the connection layer may be the same. It should be noted that filling a plurality of reflective medium layers can enhance the connection strength between the substrate and the piezoelectric layer.

In another embodiment, the medium of the plurality of reflective medium layers includes, but is not limited to, one of: vacuum, air.

In this embodiment, the left and right sides of the reflective medium layer 651, i.e., the two sides in the horizontal direction, are the piezoelectric layer 670, the lower side of the reflective medium layer 651 is the connection layer 630, and the upper side of the reflective medium layer 651 is the piezoelectric layer 670, i.e., the two sides in the vertical direction of the reflective medium layer 651 are the connection layer 630 and the piezoelectric layer 670, respectively.

In this embodiment, the piezoelectric layer 670 is disposed on the left and right sides of the reflective medium layer 653, that is, on the two sides in the horizontal direction, the connection layer 630 is disposed on the lower side of the reflective medium layer 653, and the piezoelectric layer 670 is disposed on the upper side of the reflective medium layer 653, that is, the connection layer 630 and the piezoelectric layer 670 are disposed on the two sides in the vertical direction of the reflective medium layer 653.

In this embodiment, the left and right sides of the reflective medium layer 655, i.e., the two sides in the horizontal direction, are the piezoelectric layer 670, the lower side of the reflective medium layer 655 is the connection layer 630, and the upper side of the reflective medium layer 655 is the piezoelectric layer 670, i.e., the two sides in the vertical direction of the reflective medium layer 655 are the connection layer 630 and the piezoelectric layer 670, respectively.

In this embodiment, the piezoelectric layer 670 is disposed on the left and right sides of the reflective medium layer 657, i.e., on the two sides in the horizontal direction, the connection layer 630 is disposed on the lower side of the reflective medium layer 657, and the piezoelectric layer 670 is disposed on the upper side of the reflective medium layer 657, i.e., the connection layer 630 and the piezoelectric layer 670 are disposed on the two sides of the reflective medium layer 657 in the vertical direction, respectively.

In this embodiment, the material of the piezoelectric layer 670 includes, but is not limited to, at least one of the following: aluminum nitride, aluminum oxide alloy, gallium nitride, zinc oxide, lithium tantalate, lithium niobate, lead zirconate titanate, lead magnesium niobate-lead titanate.

It should be noted that IDT structures known to those skilled in the art can be applied to the embodiments of the present invention. In another embodiment, the electrode layer comprises 3 or less sets of interdigitated structures and, correspondingly, the plurality of layers of reflective media comprises 3 or less layers of reflective media. In another embodiment, the electrode layer comprises 5 or more groups of interdigitated structures and, correspondingly, the plurality of layers of reflective media comprises 5 or more layers of reflective media.

In this embodiment, the arithmetic mean deviation of the profile of the irregular concave-convex portion of the first top portion is greater than 1 nm. It should be noted that the arithmetic mean deviation of the profile refers to the arithmetic mean of the absolute values of the profile offsets in the sampling length, and is used to indicate the surface roughness. In this embodiment, the arithmetic mean deviation of the profile of the irregular concave-convex portion of the second top portion is greater than 1 nm. In this embodiment, the arithmetic mean deviation of the profile of the irregular concave-convex portion of the third top portion is greater than 1 nm. In this embodiment, the arithmetic mean deviation of the profile of the irregular concave-convex portion at the fourth top is greater than 1 nm.

As shown in fig. 7, an embodiment of the present invention provides a SAW filter device 700, including: a substrate 710; an intermediate layer 730 on the substrate 710 for blocking leakage waves or temperature compensation; a plurality of reflective dielectric layers 750 disposed on the middle layer 730, wherein the plurality of reflective dielectric layers 750 include a reflective dielectric layer 751, a reflective dielectric layer 753, and a reflective dielectric layer 755; a piezoelectric layer 770 disposed on the intermediate layer 730, the piezoelectric layer 770 including a first side 771 and a second side 773 opposite the first side 771, the substrate 710 disposed on the first side 771, the intermediate layer 730 disposed on the first side 771, the plurality of reflective medium layers 750 disposed on the first side 771 and embedded in the piezoelectric layer 770; and an electrode layer 790 positioned on the second side 773 and on the piezoelectric layer 770, wherein the electrode layer 790 comprises an IDT 791, an IDT 793 and an IDT 795, and the IDT 791 is positioned above the reflective dielectric layer 751 and corresponds to the reflective dielectric layer 751; the IDT 793 is located above the reflecting medium layer 753 and corresponds to the reflecting medium layer 753; the IDT 795 is positioned above the reflecting medium layer 755 and corresponds to the reflecting medium layer 755; wherein the reflective medium layer 751 comprises a first top portion comprising irregular asperities and a first side portion comprising irregular asperities; the reflective medium layer 753 including a second top portion including an irregular concave-convex portion and a second side portion including an irregular concave-convex portion; the reflective medium layer 755 includes a third top portion including an irregular prominence and depression and a third side portion including an irregular prominence and depression.

It should be noted that, when a voltage is applied to the electrode layer 790, a bulk acoustic wave is generated, and the bulk acoustic wave propagates to the irregular concave-convex portions of the plurality of reflective medium layers 750 in a direction perpendicular to the piezoelectric layer 770, so that irregular reflection is generated, and the bulk acoustic wave reflected back to the surface of the second side 773 is reduced, thereby reducing parasitic resonance.

In this embodiment, the material of the substrate 710 includes, but is not limited to, at least one of the following: silicon, silicon carbide, silicon dioxide, gallium arsenide, gallium nitride, sapphire, spinel, ceramics, polymers. In this embodiment, the polymer includes, but is not limited to, at least one of: benzocyclobutene (i.e., BCB), photosensitive epoxy photoresist (e.g., SU-8), polyimide.

In this embodiment, the material of the intermediate layer 730 includes, but is not limited to, at least one of the following: polymer, insulating dielectric, polysilicon. In this embodiment, the polymer includes, but is not limited to, at least one of: benzocyclobutene (i.e., BCB), photosensitive epoxy photoresist (e.g., SU-8), polyimide. In this embodiment, the insulating dielectric includes, but is not limited to, at least one of: aluminum nitride, silicon dioxide, silicon nitride, titanium oxide.

In this embodiment, the material of the plurality of reflective medium layers 750 includes, but is not limited to, at least one of the following: polymer, insulating dielectric, polysilicon. In this embodiment, the polymer includes, but is not limited to, at least one of: benzocyclobutene (i.e., BCB), photosensitive epoxy photoresist (e.g., SU-8), polyimide. In this embodiment, the insulating dielectric includes, but is not limited to, at least one of: aluminum nitride, silicon dioxide, silicon nitride, titanium oxide.

In this embodiment, the material of the plurality of reflective medium layers 750 is different from the material of the intermediate layer 730. In another embodiment, the material of the plurality of reflective medium layers and the material of the intermediate layer may be the same. It should be noted that filling a plurality of reflective medium layers can enhance the connection strength between the intermediate layer and the piezoelectric layer.

In this embodiment, the piezoelectric layer 770 is disposed on the left and right sides of the reflective medium layer 751, i.e., on the two sides in the horizontal direction, the intermediate layer 730 is disposed on the lower side of the reflective medium layer 751, and the piezoelectric layer 770 is disposed on the upper side of the reflective medium layer 751, i.e., the intermediate layer 730 and the piezoelectric layer 770 are disposed on the two sides of the reflective medium layer 751 in the vertical direction, respectively.

In this embodiment, the piezoelectric layer 770 is disposed on the left and right sides of the reflective medium layer 753, that is, on the two sides in the horizontal direction, the intermediate layer 730 is disposed on the lower side of the reflective medium layer 753, and the piezoelectric layer 770 is disposed on the upper side of the reflective medium layer 753, that is, the intermediate layer 730 and the piezoelectric layer 770 are disposed on the two sides in the vertical direction of the reflective medium layer 753, respectively.

In this embodiment, the piezoelectric layer 770 is disposed on the left and right sides of the reflective medium layer 755, i.e., on the two sides in the horizontal direction, the middle layer 730 is disposed on the lower side of the reflective medium layer 755, and the piezoelectric layer 770 is disposed on the upper side of the reflective medium layer 755, i.e., the middle layer 730 and the piezoelectric layer 770 are disposed on the two sides in the vertical direction of the reflective medium layer 755, respectively.

In this embodiment, the material of the piezoelectric layer 770 includes, but is not limited to, at least one of the following: aluminum nitride, aluminum oxide alloy, gallium nitride, zinc oxide, lithium tantalate, lithium niobate, lead zirconate titanate, lead magnesium niobate-lead titanate. It should be noted that the acoustic impedance of the material of the intermediate layer 730 is different from the acoustic impedance of the material of the piezoelectric layer 770, so as to block the leakage wave. Furthermore, if the material of the intermediate layer 730 (e.g., silicon dioxide) has an opposite temperature-shift characteristic to the material of the piezoelectric layer 770, the TCF of the resonator device can be reduced towards 0 ppm/c, thereby increasing the frequency-temperature stability, i.e., the intermediate layer 730 is a temperature compensation layer.

It should be noted that IDT structures known to those skilled in the art can be applied to the embodiments of the present invention. In another embodiment, the electrode layer comprises 2 or less sets of interdigitated structures and, correspondingly, the plurality of layers of reflective media comprises 2 or less layers of reflective media. In another embodiment, the electrode layer comprises 4 or more groups of interdigitated structures and, correspondingly, the plurality of reflective dielectric layers comprises 4 or more than 4 reflective dielectric layers.

In this embodiment, the arithmetic mean deviation of the profile of the irregular concave-convex portion of the first top portion is greater than 1 nm. In this embodiment, the contour arithmetic mean deviation of the irregular concave-convex portion of the first side portion is greater than 1 nm. It should be noted that the arithmetic mean deviation of the profile refers to the arithmetic mean of the absolute values of the profile offsets in the sampling length, and is used to indicate the surface roughness.

In this embodiment, the arithmetic mean deviation of the profile of the irregular concave-convex portion of the second top portion is greater than 1 nm. In this embodiment, the contour arithmetic mean deviation of the irregular concave-convex portion of the second side portion is greater than 1 nm.

In this embodiment, the arithmetic mean deviation of the profile of the irregular concave-convex portion of the third top portion is greater than 1 nm. In this embodiment, the contour arithmetic mean deviation of the irregular concave-convex portion of the third side portion is greater than 1 nm.

In this embodiment, the SAW filter device 700 further includes: and a connection layer 720 between the substrate 710 and the intermediate layer 730 for bonding the substrate 710 and the intermediate layer 730. In this embodiment, the material of the connection layer 720 includes, but is not limited to, at least one of the following: polymer, insulating dielectric, polysilicon. In this embodiment, the polymer includes, but is not limited to, at least one of: benzocyclobutene (i.e., BCB), photosensitive epoxy photoresist (e.g., SU-8), polyimide. In this embodiment, the insulating dielectric includes, but is not limited to, at least one of: aluminum nitride, silicon dioxide, silicon nitride, titanium oxide.

In summary, the surface acoustic wave resonator device provided in the embodiments of the present invention includes a reflective medium layer, which is located between the piezoelectric layer and the substrate or the intermediate layer and embedded in the piezoelectric layer, wherein the reflective medium layer includes irregular concave-convex portions, and the bulk acoustic waves generated by the electrode layer are irregularly reflected at the irregular concave-convex portions, so that the bulk acoustic waves reflected to the upper surface of the piezoelectric layer can be reduced, thereby reducing the parasitic resonance.

It is understood that the examples and embodiments described herein are for illustrative purposes only and that various modifications or changes in light thereof will be suggested to persons skilled in the art and are to be included within the spirit and purview of this application and scope of the appended claims.

Claims

1. A surface acoustic wave resonator device, comprising:

a support layer;

a piezoelectric layer over the support layer, the piezoelectric layer including a first side and a second side opposite the first side, the support layer being located on the first side;

the reflecting medium layer is positioned on the first side, positioned above the supporting layer and embedded into the piezoelectric layer;

an electrode layer on the second side on the piezoelectric layer;

the reflective medium layer includes a first top portion and a first side portion, the first top portion includes a first concave-convex portion, the first side portion includes a second concave-convex portion, and roughness of the second concave-convex portion is greater than roughness of the first concave-convex portion.

2. A surface acoustic wave resonator device as set forth in claim 1, wherein the medium of said reflecting medium layer includes one of: vacuum, air.

3. A surface acoustic wave resonator device as set forth in claim 1, wherein the material of said reflective medium layer includes at least one of: polymer, insulating dielectric, polysilicon.

4. A surface acoustic wave resonator device as set forth in claim 1, wherein said electrode layer includes interdigital transducer means located above said reflective medium layer, corresponding to said reflective medium layer.

5. A surface acoustic wave resonator device as set forth in claim 1, wherein a contour number average deviation of said first concavo-convex portion is larger than 1 nm.

6. A surface acoustic wave resonator device as set forth in claim 1, wherein a contour number average deviation of said second concavo-convex portion is larger than 2 nm.

7. A surface acoustic wave resonator device as set forth in claim 1, wherein said support layer includes a substrate.

8. A surface acoustic wave resonator device as set forth in claim 7, further comprising: and the connecting layer is positioned on the first side, is positioned between the substrate and the piezoelectric layer and is used for connecting the substrate and the piezoelectric layer, and the reflecting medium layer is positioned on the connecting layer or the connecting layer is positioned on two sides of the reflecting medium layer in the horizontal direction.

9. A surface acoustic wave resonator device as set forth in claim 7, wherein said support layer further comprises: and the middle layer is positioned between the substrate and the piezoelectric layer and used for blocking leakage waves or temperature compensation, and the reflecting medium layer is positioned on the middle layer.

10. A surface acoustic wave resonator device as set forth in claim 9, wherein the material of said intermediate layer includes at least one of: polymer, insulating dielectric, polysilicon.

11. A filtering apparatus, comprising: at least one surface acoustic wave resonator device as claimed in any one of claims 1 to 10.

12. A radio frequency front end device, comprising: power amplifying means and at least one filtering means according to claim 11; the power amplifying device is connected with the filtering device.

13. A radio frequency front end device, comprising: low noise amplifying means associated with at least one filtering means according to claim 11; the low-noise amplifying device is connected with the filtering device.

14. A radio frequency front end device, comprising: multiplexing device comprising at least one filter device according to claim 11.