CN115189670A - Bulk acoustic wave resonator device, forming method thereof, filter device and radio frequency front end device - Google Patents
Bulk acoustic wave resonator device, forming method thereof, filter device and radio frequency front end device Download PDFInfo
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- H—ELECTRICITY
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Abstract
A bulk acoustic wave resonator device and a forming method thereof, a filter device and a radio frequency front end device are provided, wherein the bulk acoustic wave resonator device comprises: a cavity; at least one end of the first electrode layer is positioned above or in the cavity; the piezoelectric layer, the cavity and the first electrode layer are positioned on the first side of the piezoelectric layer; the second electrode layer is positioned on the second side; a first passive structure on the first side in contact with at least one edge of a first sublayer of a first electrode layer; a second passive structure on the second side in contact with at least one edge of a third sublayer of the second electrode layer; the first passive structure includes: a first raised part located inside the resonance region; the first extending part is positioned outside the resonance area, and the first lifting part is raised relative to the first extending part; the second passive structure includes: a second raised part located inside the resonance region; and the second extending part is positioned outside the resonance area, and the second lifting part is raised relative to the second extending part.The invention inhibits the parasitic edge mode and improves the Z p And the corresponding Q value.
Description
The present application claims priority of chinese patent application having application number 202110808180.6 entitled "bulk acoustic wave resonator device and method of forming the same, filter device and rf front end device", filed at 16/7/2021, which is incorporated herein by reference.
Technical Field
The invention relates to the technical field of semiconductors, in particular to a bulk acoustic wave resonance device, a forming method thereof, 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 (PA), an antenna switch, an RF filter, a multiplexer (multiplexer) including a duplexer (duplexer), and a Low Noise Amplifier (LNA), etc. 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.
The SAW resonator and the BAW resonator have high quality factor values (Q values), and are made into RF filters with low insertion loss (insertion loss) and high out-of-band rejection (out-of-band rejection), namely SAW filters and BAW filters, which are mainstream RF filters used in wireless communication equipment such as mobile phones and base stations at present. Where Q is the quality factor value of the resonator, defined as the center frequency divided by the 3dB bandwidth of the resonator. The frequency of use of the SAW filter is generally from 0.4GHz to 2.7GHz and the frequency of use of the BAW filter is generally from 0.7GHz to 7GHz.
BAW resonators perform better than SAW resonators, but are more expensive to manufacture than SAW resonators due to the complex processing steps. However, as wireless communication technology gradually evolves, more and more frequency bands are used, and meanwhile, with the application of frequency band overlapping use technology such as carrier aggregation, mutual interference between wireless frequency bands becomes more and more serious. The high performance BAW technology can solve the problem of mutual interference between frequency bands. With the advent of the 5G era, higher communication frequency bands are introduced into wireless mobile networks, and currently, only BAW technology can solve the problem of filtering in high frequency bands.
Fig. 1 shows a circuit of a BAW filter, comprising a ladder circuit consisting of a plurality of BAW resonators, a first end of the circuit being connected to a transceiving end and a second end of the circuit being connected to an antenna, wherein f1, f2, f3, f4 respectively represent 4 different frequencies. In each BAW resonator, metal electrodes on two sides of a piezoelectric layer of the resonator generate alternative positive and negative voltages, the piezoelectric layer generates acoustic waves through the alternative positive and negative voltages, and the acoustic waves in the resonator vertically propagate along the thickness direction of the piezoelectric layer. In order to form resonance, the acoustic wave needs to generate total reflection on the upper surface of the upper metal electrode and the lower surface of the lower metal electrode to form a standing acoustic wave. The condition for the reflection of the acoustic wave is that the acoustic impedance of the contact area with the upper surface of the upper metal electrode and the lower surface of the lower metal electrode is greatly different from the acoustic impedance of the metal electrode.
The performance of an RF filter depends on the performance of the resonator, which is determined by the minimum series impedance (Z) of the resonator s Maximum parallel impedance (parallel impedance) Z p And an electromechanical coupling coefficient (Kt) 2 Isoparametric representation in which Z s And Z p Representing thermal losses, acoustic losses, etc. in the resonator. The resonator operating at the series resonance frequency f s When the input impedance reaches Z, the value of the input impedance is minimum s (ii) a The resonator operating at a parallel resonance frequency f p When the input impedance reaches the maximum value, Z is reached p . Electromechanical coupling coefficient Kt 2 Represents Z s And Z p The frequency difference between them, affects the passband (passband) bandwidth of the RF filter. With a higher Kt 2 Or Z p And lower Z s The performance of the resonator of (2) is better. Those skilled in the art will recognize that resonator design requirements at Kt are 2 And Z p By taking a trade-off between, i.e. raising Kt 2 At the same time, Z is reduced p Lifting of Z p While lowering Kt 2 。
A Film Bulk Acoustic Wave Resonator (FBAR) is a BAW Resonator which can confine Acoustic energy in a device, and a resonant area of the BAW Resonator is vacuum or air above the FBAR Resonator, and a cavity exists below the FBAR Resonator.
Fig. 2 shows a schematic structure of an FBAR 200. The FBAR 200 includes: a substrate 201; a cavity 203 embedded in the substrate 201; an electrode layer 205 (i.e., a lower electrode layer) on the substrate 201 and the cavity 203, covering the cavity 203; a piezoelectric layer 207 on said electrode layer 205; and an electrode layer 209 (i.e., an upper electrode layer) on the piezoelectric layer 207; the overlapping region of the electrode layer 205, the piezoelectric layer 207, and the electrode layer 209 is a resonance region of the FBAR 200. Two sets of acoustic waves are generated in the resonance region, the first set of acoustic waves includes a compressional wave (longitudinal wave) and a shear wave (shear wave) propagating in a direction perpendicular to the piezoelectric layer 207, the second set of acoustic waves includes an acoustic wave (RL wave) propagating towards the lateral edge of the piezoelectric layer 207, and propagating along the lateral surfaces of the two electrode layers to the lateral edge of the piezoelectric layer 207, and exciting a parasitic edge mode (spectral mode) at the edge to generate a parasitic resonance, thereby reducing the Z resonance p And corresponding Q values.
Disclosure of Invention
The invention provides a bulk acoustic wave resonance device, which improves the continuity of acoustic waves propagated from a resonance region into an attenuation region, thereby reducing parasitic resonance generated in the propagation process, attenuating the acoustic waves propagated transversely, inhibiting parasitic edge modes, and improving Z p And corresponding Q value, while for Kt 2 So that the performance of the filtering means comprising the bulk acoustic wave resonator device, e.g. insertion loss, out-of-band rejection, can be improved.
In order to solve the above problems, a technical solution of the present invention provides a bulk acoustic wave resonator device, including: a cavity; a first electrode layer, at least one end of which is located above or in the cavity, the first electrode layer comprising a first sub-layer and a second sub-layer, the first sub-layer contacting the second sub-layer; the piezoelectric layer comprises a first side and a second side opposite to the first side in the vertical direction, the cavity is located on the first side, the first electrode layer is located on the first side, the first sub-layer is also in contact with the piezoelectric layer, and the first sub-layer is located between the second sub-layer and the piezoelectric layer; the second electrode layer is positioned on the second side and comprises a third sub-layer and a fourth sub-layer, the third sub-layer is in contact with the piezoelectric layer, the third sub-layer is also in contact with the fourth sub-layer, the third sub-layer is positioned between the piezoelectric layer and the fourth sub-layer, and the overlapped area of the first sub-layer, the third sub-layer and the piezoelectric layer is a resonance area; a first passive structure on the first side in contact with at least one edge of the first sublayer; a second passive structure on the second side in contact with at least one edge of the third sublayer; wherein the first passive structure comprises: the first lifting part is positioned on the inner side of the resonance region, a first superposition part is arranged on at least one edge of the first sublayer, and the first lifting part is used for matching the acoustic impedance of the resonance region and at least one attenuation region on the outer side of the resonance region so that more sound waves generated in the resonance region enter the at least one attenuation region; a first passivation portion located between the first raised portion and the first electrode layer for electrically isolating the first electrode layer from the first passive structure; a first extension located outside the resonance region and within the at least one attenuation region for attenuating sound waves entering the at least one attenuation region, the first lift portion being raised relative to the first extension; the second passive structure includes: a second raised part which is positioned inside the resonance region and has a second overlapping part with at least one edge of the third sublayer, wherein the second raised part is used for matching acoustic impedances of the resonance region and the at least one attenuation region so that more sound waves generated in the resonance region enter the at least one attenuation region; a second passivation portion located between the second raised portion and the second electrode layer for electrically isolating the second electrode layer from the second passive structure; the second extending portion is located outside the resonance region and inside the at least one attenuation region and used for attenuating the sound waves entering the at least one attenuation region, and the second lifting portion is convex relative to the second extending portion.
Optionally, at least one edge of the first sublayer is in a downhill shape corresponding to the first passive structure; at least one edge of the third sublayer is in a downhill shape corresponding to the second passive structure.
Optionally, the size of the second sublayer is smaller than that of the first sublayer, and the size of the fourth sublayer is smaller than that of the third sublayer.
Optionally, at least one edge of the second sub-layer is located inside at least one edge of the corresponding first sub-layer, and at least one edge of the fourth sub-layer is located inside at least one edge of the corresponding third sub-layer.
Optionally, at least one edge of the first sub-layer includes a first edge, at least one edge of the second sub-layer includes a second edge, the first edge vertically corresponds to the second edge, and the second edge is located inside the first edge.
Optionally, at least one edge of the third sub-layer includes a third edge, at least one edge of the fourth sub-layer includes a fourth edge, the third edge vertically corresponds to the fourth edge, and the fourth edge is located inside the third edge.
Optionally, the first passive structure and the second passive structure surround the resonance region.
Optionally, a thickness of the first passive structure is equal to or less than a thickness of the first electrode layer, and a thickness of the second passive structure is equal to or less than a thickness of the second electrode layer.
Optionally, the at least one attenuation region includes a first attenuation region, a first cut-off frequency of the first attenuation region is equal to or less than a cut-off frequency of the resonance region, and the first attenuation region corresponds to a region where the first extension portion, the piezoelectric layer and the second extension portion coincide.
Optionally, the method further includes: a first electrode extension layer located at the first side and connected with the first electrode layer; and the second electrode extension layer is positioned on the second side and is connected with the second electrode layer.
Optionally, the at least one attenuation region includes a second attenuation region, a second cut-off frequency of the second attenuation region is equal to or lower than the cut-off frequency of the resonance region, and the second attenuation region corresponds to a region where the second electrode extension layer, the piezoelectric layer and the first extension portion overlap.
Optionally, the at least one attenuation region includes a third attenuation region, a third cutoff frequency of the third attenuation region is equal to or lower than the cutoff frequency of the resonance region, and the third attenuation region corresponds to a region where the second extension portion, the piezoelectric layer, and the first electrode extension layer coincide.
Optionally, the width of the first raised part is an integral multiple of one-half wavelength of the sound wave generated in the resonance region, and the width of the second raised part is an integral multiple of one-half wavelength of the sound wave generated in the resonance region.
Optionally, the material of the first raised part includes a metal, the material of the first extension part includes a metal, the material of the second raised part includes a metal, and the material of the second extension part includes a metal.
Optionally, the first sub-layer is located on one side of the first raised part in the vertical direction, and the second sub-layer is located on one side of the first raised part in the horizontal direction; the third sub-layer is located on one side of the second lifting part in the vertical direction, and the fourth sub-layer is located on one side of the second lifting part in the horizontal direction.
Optionally, the first overlapping portion extends to at least one edge of the corresponding second sub-layer along the horizontal direction, and the second overlapping portion extends to at least one edge of the corresponding fourth sub-layer along the horizontal direction.
Optionally, a thickness of the first extension portion is smaller than a thickness of the first electrode layer, and a thickness of the second extension portion is smaller than a thickness of the second electrode layer.
Optionally, the first extending portion includes a first sub-portion and a second sub-portion, the second sub-portion and the piezoelectric layer are located on two sides of the first sub-portion, and a material of the first sub-portion is different from a material of the second sub-portion.
Optionally, the second extending portion includes a third sub-portion and a fourth sub-portion, the piezoelectric layer and the fourth sub-portion are located on two sides of the third sub-portion, and a material of the third sub-portion is different from a material of the fourth sub-portion.
Optionally, the material of the first passivation includes a dielectric, and the material of the second passivation includes a dielectric.
Optionally, the first passivation is further located between the piezoelectric layer and the first extension, and the second passivation is further located between the piezoelectric layer and the second extension.
Optionally, a first empty slot is included between the first extension portion and the piezoelectric layer, and a second empty slot is included between the piezoelectric layer and the second extension portion.
Optionally, the method further includes: a third passivation portion located on the second side and contacting the second electrode layer; and the surrounding groove is positioned in the third passivation part, positioned on the inner side of the resonance area, positioned on the inner side of the second raised part and adjacent to the second raised part.
Optionally, the shape of the surrounding groove includes: circular, elliptical, or polygonal.
Optionally, the method further includes: a third passivation portion located on the first side and contacting the first electrode layer; and the surrounding type groove is positioned in the third passivation part, is positioned on the inner side of the resonance area, is positioned on the inner side of the first raised part and is adjacent to the first raised part.
Optionally, the shape of the surrounding groove includes: circular, elliptical, or polygonal.
Correspondingly, the technical scheme of the invention also provides a filtering device, which comprises: at least one bulk acoustic wave resonator device as described in one of the above.
Correspondingly, the technical solution of the present invention further provides a radio frequency front end device, including: a power amplifying device and at least one filtering device as described above; the power amplifying device is connected with the filtering device.
Correspondingly, the technical solution of the present invention further provides a radio frequency front end device, which is characterized by comprising: low noise amplification means and at least one filtering means as described in one of the above; the low-noise amplifying device is connected with the filtering device.
Correspondingly, the technical solution of the present invention further provides a radio frequency front end device, which is characterized by comprising: multiplexing means comprising at least one filtering means as described in one of the above.
Correspondingly, the technical scheme of the invention also provides a forming method of the bulk acoustic wave resonance device, which comprises the following steps: forming a piezoelectric layer including a first side and a second side opposite the first side in a vertical direction; forming a first electrode layer on the first side, the forming the first electrode layer including forming a first sub-layer and a second sub-layer, the first sub-layer being between the second sub-layer and the piezoelectric layer, the first sub-layer contacting the piezoelectric layer, the first sub-layer also contacting the second sub-layer; forming a second electrode layer on the second side, wherein the forming of the second electrode layer includes forming a third sub-layer and a fourth sub-layer, the third sub-layer is located between the piezoelectric layer and the fourth sub-layer, the third sub-layer contacts the piezoelectric layer, the third sub-layer also contacts the fourth sub-layer, and a region where the first sub-layer, the third sub-layer and the piezoelectric layer are overlapped is a resonance region; forming a first passive structure on the first side in contact with at least one edge of the first sublayer; wherein the first passive structure comprises: the first lifting part is raised relative to the first extending part; the first raised part is positioned on the inner side of the resonance region, and has a first overlapping part with at least one edge of the first sublayer, and the first raised part is used for matching acoustic impedances of the resonance region and at least one attenuation region on the outer side of the resonance region, so that more sound waves generated in the resonance region enter the at least one attenuation region; the first passivation is located between the first raised portion and the first electrode layer, contacting at least one edge of the first sub-layer, for electrically isolating the first electrode layer from the first passive structure; the first extension part is positioned outside the resonance region and inside the at least one attenuation region and is used for attenuating the sound waves entering the at least one attenuation region; forming a second passive structure on the second side in contact with at least one edge of the third sublayer, wherein the second passive structure comprises: the second lifting part is raised relative to the second extending part; the second lifting part is positioned inside the resonance region and provided with a second overlapping part with at least one edge of the third sublayer, and the second lifting part is used for matching acoustic impedances of the resonance region and the at least one attenuation region so that more sound waves generated in the resonance region enter the at least one attenuation region; the second passivation is located between the second raised portion and the second electrode layer, contacting at least one edge of the third sub-layer, for electrically isolating the second electrode layer from the second passive structure; the second extension portion is located outside the resonance region and inside the at least one attenuation region, and is used for attenuating the sound waves entering the at least one attenuation region.
Optionally, the forming of the first sub-layer includes forming at least one first downward slope edge corresponding to the first passive structure, and the forming of the third sub-layer includes forming at least one second downward slope edge corresponding to the second passive structure.
Optionally, the size of the second sublayer is smaller than that of the first sublayer, and the size of the fourth sublayer is smaller than that of the third sublayer.
Optionally, at least one edge of the second sub-layer is located inside at least one edge of the corresponding first sub-layer, and at least one edge of the fourth sub-layer is located inside at least one edge of the corresponding third sub-layer.
Optionally, the first passive structure and the second passive structure surround the resonance region.
Optionally, a thickness of the first passive structure is equal to or less than a thickness of the first electrode layer, and a thickness of the second passive structure is equal to or less than a thickness of the second electrode layer.
Optionally, the forming the first passive structure includes forming a first passivation layer on the first side to cover the first electrode layer; forming a first overlap layer, contacting the first passivation layer, wherein at least one edge of the first overlap layer and at least one edge of the first sub-layer have an overlapped part; wherein the first passivation layer includes the first passivation portion; wherein the first lap layer comprises the first raised part and the first extending part.
Optionally, the forming the second passive structure includes forming a second passivation layer on the second side to cover the second electrode layer; forming a second overlap layer, contacting the second passivation layer, wherein at least one edge of the second overlap layer and at least one edge of the third sub-layer have an overlapped part; wherein the second passivation layer includes the second passivation portion; wherein the second lap layer includes the second raised portion and the second extending portion.
Optionally, the at least one attenuation region includes a first attenuation region, a first cut-off frequency of the first attenuation region is equal to or less than a cut-off frequency of the resonance region, and the first attenuation region corresponds to a region where the first extension portion, the piezoelectric layer and the second extension portion coincide.
Optionally, the method further includes: forming a first electrode extension layer positioned on the first side and connected with the first electrode layer; and forming a second electrode extension layer which is positioned on the second side and is connected with the second electrode layer.
Optionally, the at least one attenuation region includes a second attenuation region, a second cut-off frequency of the second attenuation region is equal to or lower than the cut-off frequency of the resonance region, and the second attenuation region corresponds to a region where the second electrode extension layer, the piezoelectric layer and the first extension portion overlap.
Optionally, the at least one attenuation region includes a third attenuation region, a third cutoff frequency of the third attenuation region is equal to or lower than the cutoff frequency of the resonance region, and the third attenuation region corresponds to a region where the second extension portion, the piezoelectric layer, and the first electrode extension layer overlap.
Optionally, the first overlapping portion extends to at least one edge of the corresponding second sub-layer along the horizontal direction, and the second overlapping portion extends to at least one edge of the corresponding fourth sub-layer along the horizontal direction.
Optionally, the first sub-layer is located on one side of the first raised part in the vertical direction, and the second sub-layer is located on one side of the first raised part in the horizontal direction; the third sub-layer is located on one side of the second lifting portion in the vertical direction, and the fourth sub-layer is located on one side of the second lifting portion in the horizontal direction.
Optionally, a thickness of the first extending portion is smaller than a thickness of the first electrode layer, and a thickness of the second extending portion is smaller than a thickness of the second electrode layer.
Optionally, the width of the first raised part is an integral multiple of one-half wavelength of the sound wave generated in the resonance region, and the width of the second raised part is an integral multiple of one-half wavelength of the sound wave generated in the resonance region.
Optionally, the forming the first overlap layer includes; forming a first butt-strap sublayer and a second butt-strap sublayer, wherein the second butt-strap sublayer and the piezoelectric layer are positioned on two sides of the first butt-strap sublayer, and the material of the first butt-strap sublayer is different from that of the second butt-strap sublayer.
Optionally, the forming the second overlap layer includes; and forming a third lapping sub-layer and a fourth lapping sub-layer, wherein the fourth lapping sub-layer and the piezoelectric layer are positioned at two sides of the third lapping sub-layer, and the material of the third lapping sub-layer is different from that of the fourth lapping sub-layer.
Optionally, the method further includes: forming a first sacrificial layer between the first extension and the piezoelectric layer; forming a second sacrificial layer between the second extension and the piezoelectric layer.
Optionally, the method further includes: removing the first sacrificial layer to form a first empty groove located between the first extending portion and the piezoelectric layer; and removing the second sacrificial layer to form a second empty groove which is positioned between the second extending part and the piezoelectric layer.
Optionally, the first passivation is further located between the piezoelectric layer and the first extension, and the second passivation is further located between the piezoelectric layer and the second extension.
Optionally, the method further includes: forming a third passivation portion located on the second side and in contact with the second electrode layer; and forming a surrounding groove, which is positioned in the third passivation part, is positioned inside the resonance area, is positioned inside the second raised part, and is adjacent to the second raised part.
Optionally, the shape of the surrounding groove includes: circular, elliptical, or polygonal.
Optionally, the method further includes: forming a third passivation portion located on the first side and in contact with the first electrode layer; and forming a surrounding type groove, wherein the surrounding type groove is positioned in the third passivation part, positioned on the inner side of the resonance area, positioned on the inner side of the first lifting part and adjacent to the first lifting part.
Optionally, the shape of the surrounding groove includes: circular, elliptical, or polygonal.
Compared with the prior art, the technical scheme of the invention has the following advantages:
in the bulk acoustic wave resonator device according to the aspect of the present invention, the raised portion of the passive structure is located inside the resonance region, and has a portion overlapping with the electrode layer, so that acoustic impedances of the resonance region and the attenuation region outside the resonance region can be matched, and thus more acoustic waves generated by the resonance region propagate into the attenuation region. In addition, the thickness of the raised part is matched with the thickness of the sub-layer of the electrode layer on the horizontal direction side, namely the thickness of the raised part is close to the thickness of the sub-layer, so that the continuity of sound waves which are transmitted from the resonance region into the attenuation region can be improved, and the parasitic resonance generated in the transmission process can be reduced. In addition, the truncation of the attenuation regionA cut-off frequency (cutoff frequency) matching (e.g., equal to or less than) the cut-off frequency of the resonance region may attenuate sound waves entering the attenuation region, suppress parasitic edge modes, promote Z p And corresponding Q value, while for Kt 2 The influence of (c) is small. The cutoff frequency is a frequency corresponding to a wave number (wave number) of 0 on a dispersion curve (dispersion curve). Wherein, for Kt 2 Is less affected because the passive structure is not electrically connected to the electrode layer.
Further, still include: a third passivation portion in contact with the electrode layer; and the surrounding groove is positioned in the third passivation part, positioned on the inner side of the resonance area, positioned on the inner side of the lifting part and adjacent to the lifting part. The surrounding groove, a first section area formed by the surrounding groove and a second section area formed by the lifting part are additionally arranged at the inner side of the resonance area. The cutoff frequency of the first section region is set to be higher than the cutoff frequency of the middle part of the resonance region inside the surrounding groove, the cutoff frequency of the second section region is set to be lower than the cutoff frequency of the middle part, a piston mode (piston mode) is formed, the higher order parasitic mode of transverse sound waves is suppressed, and the series resonance frequency (f) is reduced s ) Near and less than f s Clutter of the portion (c).
In the method for forming the bulk acoustic wave resonator device according to the technical scheme of the present invention, the raised portion of the formed passive structure is located inside the resonance region and has a superposition portion with the electrode layer, and acoustic impedances of the resonance region and the attenuation region outside the resonance region can be matched, so that more acoustic waves generated by the resonance region are propagated into the attenuation region. In addition, the thickness of the raised part is matched with the thickness of the sub-layer of the electrode layer on the horizontal direction side of the raised part, namely the thickness of the raised part is close to that of the sub-layer, so that the continuity of the sound wave which is transmitted from the resonance region into the attenuation region can be improved, and the parasitic resonance generated in the transmission process can be reduced. In addition, the cutoff frequency (cutoff frequency) of the attenuation region is matched with (e.g., equal to or less than) the cutoff frequency of the resonance region, so that the sound wave entering the attenuation region can be attenuated, parasitic edge modes can be suppressed, and the Z can be improved p And corresponding Q value, while for Kt 2 The influence of (c) is small. The cutoff frequency is a frequency corresponding to a wave number (wave number) of 0 on a dispersion curve (dispersion curve). Wherein, for Kt 2 Is less affected because the passive structure is not electrically connected to the electrode layer.
Further, the method also comprises the following steps: forming a third passivation portion in contact with the electrode layer; and forming a surrounding groove, which is positioned in the third passivation part, is positioned at the inner side of the resonance area, is positioned at the inner side of the lifting part and is adjacent to the lifting part. The surrounding groove, a first section area formed by the surrounding groove and a second section area formed by the lifting part are additionally arranged at the inner side of the resonance area. The cutoff frequency of the first section region is set to be higher than the cutoff frequency of the middle part of the resonance region inside the surrounding groove, the cutoff frequency of the second section region is set to be lower than the cutoff frequency of the middle part, a piston mode (piston mode) is formed, the higher order parasitic mode of transverse sound waves is suppressed, and the series resonance frequency (f) is reduced s ) Near and less than f s Clutter of the portion (c).
Drawings
Fig. 1 is a schematic diagram of a bulk acoustic wave filter circuit;
fig. 2 is a schematic structural diagram of an FBAR 200;
fig. 3 to 6 are schematic structural diagrams of a bulk acoustic wave resonator 3000 according to an embodiment of the present invention;
FIG. 7 is a schematic diagram of a structure of a hexagonal crystal grain;
FIG. 8 (i) is a schematic diagram of the structure of an orthorhombic crystal grain;
FIG. 8 (ii) is a schematic diagram of a tetragonal crystal grain structure;
FIG. 8 (iii) is a schematic structural view of a cubic crystal grain;
fig. 9 is a schematic diagram of a dispersion curve 600 of a bulk acoustic wave resonator device according to an embodiment of the present invention;
FIG. 10 is a schematic diagram of a parallel impedance curve 700 of a bulk acoustic wave resonator device in accordance with an embodiment of the present invention;
FIG. 11 is a schematic diagram of a parallel impedance curve 800 of a bulk acoustic wave resonator device in accordance with an embodiment of the present invention;
fig. 12 to 15 are schematic structural diagrams of a bulk acoustic wave resonator device 3000 according to an embodiment of the present invention, where fig. 12 is a schematic structural diagram of a first cross section of the bulk acoustic wave resonator device 3000 and a schematic distribution diagram of sound velocities in corresponding regions;
fig. 16 is a schematic view of a sound wave dispersion curve of a bulk acoustic wave resonator device according to an embodiment of the present invention;
fig. 17 is a first schematic cross-sectional structure diagram of a bulk acoustic wave resonator device 3000 according to another embodiment of the present invention and a sound velocity distribution diagram of a corresponding region;
fig. 18 to 19 are schematic structural views of a bulk acoustic wave resonator 9000 according to an embodiment of the present invention;
fig. 20 is a schematic structural diagram of a wireless communication device 1000;
FIG. 21 is a flow chart illustrating a method 1100 for forming a bulk acoustic wave resonator device in accordance with an embodiment of the present invention;
fig. 22 to 25 are schematic structural diagrams of a cross section a of a method for forming a bulk acoustic wave resonator 1200 according to an embodiment of the present invention;
fig. 26 is a schematic structural diagram of a cross section a of a method for forming a bulk acoustic wave resonator 1200 according to another embodiment of the present invention;
fig. 27 and 28 are schematic structural diagrams of a section a of a method for forming a bulk acoustic wave resonator device 1200 according to yet another embodiment of the present invention, where fig. 28 is a schematic structural diagram of a first cross section of the bulk acoustic wave resonator device 1200 and a schematic sound velocity distribution diagram of a corresponding region;
fig. 29 to 32 are schematic structural diagrams of a cross section a of a method for forming a bulk acoustic wave resonator 1200 according to an embodiment of the present invention;
FIG. 33 is a graph comparing two series admittance curves.
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, however, the present invention may be practiced otherwise than as specifically described and thus is not limited to the specific embodiments disclosed below.
As described in the background section, the acoustic wave generated in the resonance region propagates to the lateral edges of the piezoelectric layer along the side surfaces of the two electrode layers, and excites a parasitic edge mode at the edges to generate a parasitic resonance, thereby lowering Z p And the corresponding Q value.
The inventors of the present invention have found that the raised portion of the passive structure is located inside the resonance region and has an overlap with the electrode layer, so that the acoustic impedances of the resonance region and the attenuation region outside the resonance region can be matched, and more of the acoustic waves generated by the resonance region propagate into the attenuation region. The inventors of the present invention have also found that matching the thickness of the raised portion with the thickness of the sub-layer of the electrode layer on the horizontal direction side thereof, that is, the thickness of the raised portion is close to the thickness of the sub-layer, can improve the continuity of the acoustic wave propagating from the resonance region into the attenuation region, thereby reducing the parasitic resonance generated during propagation. The inventors of the present invention have also found that the cut-off frequency of the attenuation region matches (e.g., is equal to or less than) the cut-off frequency of the resonance region, which can attenuate the acoustic waves entering the attenuation region, suppress parasitic edge modes, and promote Z p And corresponding Q value, while for Kt 2 The influence of (c) is small.
To solve the above problem, an embodiment of the present invention provides a bulk acoustic wave resonator device, including: a cavity; a first electrode layer, at least one end of which is located above or in the cavity, the first electrode layer comprising a first sub-layer and a second sub-layer, the first sub-layer contacting the second sub-layer; the piezoelectric layer comprises a first side and a second side opposite to the first side in the vertical direction, the cavity is located on the first side, the first electrode layer is located on the first side, the first sub-layer is also in contact with the piezoelectric layer, and the first sub-layer is located between the second sub-layer and the piezoelectric layer; the second electrode layer is positioned on the second side and comprises a third sublayer and a fourth sublayer, the third sublayer is in contact with the piezoelectric layer and also in contact with the fourth sublayer, the third sublayer is positioned between the piezoelectric layer and the fourth sublayer, and the superposed area of the first sublayer, the third sublayer and the piezoelectric layer is a resonance area; a first passive structure on the first side in contact with at least one edge of the first sublayer; a second passive structure on the second side in contact with at least one edge of the third sublayer;
wherein the first passive structure comprises: the first lifting part is positioned on the inner side of the resonance region, a first superposition part is arranged on at least one edge of the first sublayer, and the first lifting part is used for matching the acoustic impedance of the resonance region and at least one attenuation region on the outer side of the resonance region so that more sound waves generated in the resonance region enter the at least one attenuation region; a first passivation portion located between the first raised portion and the first electrode layer for electrically isolating the first electrode layer from the first passive structure; a first extension located outside the resonance region and within the at least one attenuation region for attenuating sound waves entering the at least one attenuation region, the first raised portion being raised relative to the first extension;
wherein the second passive structure comprises: a second raised part which is positioned inside the resonance region and has a second overlapping part with at least one edge of the third sublayer, wherein the second raised part is used for matching acoustic impedances of the resonance region and the at least one attenuation region so that more sound waves generated in the resonance region enter the at least one attenuation region; a second passivation portion located between the second raised portion and the second electrode layer for electrically isolating the second electrode layer from the second passive structure; and the second extension part is positioned outside the resonance region and in the at least one attenuation region and is used for attenuating the sound waves entering the at least one attenuation region, and the second lifting part is raised relative to the second extension part.
In some embodiments, at least one edge of the first sublayer is downhill, corresponding to the first passive structure; at least one edge of the third sublayer is in a downhill shape and corresponds to the second passive structure.
In some embodiments, the size of the second sublayer is smaller than the size of the first sublayer, and the size of the fourth sublayer is smaller than the size of the third sublayer.
In some embodiments, at least one edge of the second sublayer is located inward of a corresponding at least one edge of the first sublayer, and at least one edge of the fourth sublayer is located inward of a corresponding at least one edge of the third sublayer.
In some embodiments, the at least one edge of the first sublayer comprises a first edge and the at least one edge of the second sublayer comprises a second edge, the first edge vertically corresponding to the second edge, the second edge being located inward of the first edge.
In some embodiments, the at least one edge of the third sublayer comprises a third edge, the at least one edge of the fourth sublayer comprises a fourth edge, the third edge vertically corresponding to the fourth edge, the fourth edge being located inward of the third edge.
In some embodiments, the first passive structure and the second passive structure surround the resonance region.
In some embodiments, the first passive structure has a thickness equal to or less than a thickness of the first electrode layer, and the second passive structure has a thickness equal to or less than a thickness of the second electrode layer.
In some embodiments, the at least one attenuation region includes a first attenuation region having a first cutoff frequency equal to or less than a cutoff frequency of the resonance region, the first attenuation region corresponding to a region where the first extension, the piezoelectric layer, and the second extension coincide.
In some embodiments, the bulk acoustic wave resonator device further comprises: a first electrode extension layer located at the first side and connected with the first electrode layer; and the second electrode extension layer is positioned on the second side and is connected with the second electrode layer.
In some embodiments, the at least one attenuation region includes a second attenuation region having a second cutoff frequency equal to or lower than a cutoff frequency of the resonance region, the second attenuation region corresponding to a region where the second electrode extension layer, the piezoelectric layer, and the first extension portion coincide with each other.
In some embodiments, the at least one attenuation region includes a third attenuation region having a third cutoff frequency equal to or less than the cutoff frequency of the resonance region, the third attenuation region corresponding to a region where the second extension portion, the piezoelectric layer, and the first electrode extension layer coincide.
In some embodiments, the width of the first raised portion is an integer multiple of one-half wavelength of the acoustic wave generated within the resonance region, and the width of the second raised portion is an integer multiple of one-half wavelength of the acoustic wave generated within the resonance region.
In some embodiments, the material of the first raised portion comprises a metal, the material of the first extension portion comprises a metal, the material of the second raised portion comprises a metal, and the material of the second extension portion comprises a metal.
In some embodiments, the first sub-layer is located on one side of the first raised portion in the vertical direction, and the second sub-layer is located on one side of the first raised portion in the horizontal direction; the third sub-layer is located on one side of the second lifting part in the vertical direction, and the fourth sub-layer is located on one side of the second lifting part in the horizontal direction.
In some embodiments, the first overlapping portion extends in a horizontal direction to at least one edge of the corresponding second sub-layer, and the second overlapping portion extends in a horizontal direction to at least one edge of the corresponding fourth sub-layer.
In some embodiments, the first extension portion has a thickness less than a thickness of the first electrode layer, and the second extension portion has a thickness less than a thickness of the second electrode layer.
In some embodiments, the first extending portion includes a first sub-portion and a second sub-portion, the second sub-portion and the piezoelectric layer are located on two sides of the first sub-portion, and a material of the first sub-portion is different from a material of the second sub-portion.
In some embodiments, the second extending portion includes a third sub-portion and a fourth sub-portion, the piezoelectric layer and the fourth sub-portion are located on two sides of the third sub-portion, and a material of the third sub-portion is different from a material of the fourth sub-portion.
In some embodiments, the material of the first passivation comprises a dielectric and the material of the second passivation comprises a dielectric.
In some embodiments, the first passivation is also located between the piezoelectric layer and the first extension, and the second passivation is also located between the piezoelectric layer and the second extension.
In some embodiments, a first void is included between the first extension and the piezoelectric layer, and a second void is included between the piezoelectric layer and the second extension.
In some embodiments, further comprising: a third passivation portion located on the second side and contacting the second electrode layer; and the surrounding groove is positioned in the third passivation part, positioned on the inner side of the resonance area, positioned on the inner side of the second raised part and adjacent to the second raised part.
In some embodiments, the shape of the encircling groove comprises: circular, elliptical, or polygonal.
The raised portion of the passive structure is located inside the resonance region and has an overlap with the electrode layer, so that acoustic impedances of the resonance region and the attenuation region outside the resonance region can be matched, and more sound waves generated by the resonance region propagate into the attenuation region. In addition, the thickness of the raised part is matched with the thickness of the sub-layer of the electrode layer on the horizontal direction side, namely the thickness of the raised part is close to the thickness of the sub-layer, so that the continuity of sound waves which are transmitted from the resonance region into the attenuation region can be improved, and the parasitic resonance generated in the transmission process can be reduced. In addition, the cut-off frequency of the attenuation region is matched (e.g., equal to or less than)The cut-off frequency of the resonance region can attenuate the sound wave entering the attenuation region, inhibit the parasitic edge mode and improve the Z p And corresponding Q value, while for Kt 2 Has a smaller influence.
Fig. 3 to 6 show one embodiment of the bulk acoustic wave resonator device of the present invention, but the present invention can be implemented in other ways than those described herein, and thus the present invention is not limited to the embodiments disclosed below. Wherein, fig. 3 is a first cross-sectional structure diagram of the bulk acoustic wave resonator device, fig. 4 is a second cross-sectional structure diagram of the bulk acoustic wave resonator device, fig. 5 is a first top view structure diagram of the first electrode layer of the bulk acoustic wave resonator device relative to the first cross-section, and fig. 6 is a second top view structure diagram of the second electrode layer of the bulk acoustic wave resonator device relative to the first cross-section.
Fig. 3 is a schematic structural diagram of a cross section a of a bulk acoustic wave resonator 3000 according to an embodiment of the present invention.
As shown in fig. 3, the bulk acoustic wave resonator device 3000 includes: a piezoelectric layer 3001, the piezoelectric layer 3001 including a first side 3002 and a second side 3003 opposite the first side 3002 in a vertical direction; a first electrode layer 3004 on the first side 3002 and contacting the piezoelectric layer 3001, wherein the first electrode layer 3004 includes a first sub-layer a and a second sub-layer b, the first sub-layer a contacts the piezoelectric layer 3001, the second sub-layer b contacts the first sub-layer a, the first sub-layer a is located between the piezoelectric layer 3001 and the second sub-layer b, the first sub-layer a includes a first edge and a second edge opposite to the first edge in a horizontal direction, the second sub-layer b includes a third edge and a fourth edge opposite to the third edge in a horizontal direction, the first edge is in a down slope shape, the third edge is located inside the first edge, the fourth edge is aligned with the second edge, and the size of the second sub-layer b is smaller than the size of the first sub-layer a; a first electrode extension layer 3005 on the first side 3002, contacting the piezoelectric layer 3001, and connected to the second edge and the fourth edge; a second electrode layer 3006 on the second side 3003, contacting the piezoelectric layer 3001, wherein the second electrode layer 3006 includes a third sublayer c and a fourth sublayer d, the third sublayer c contacts the piezoelectric layer 3001, the fourth sublayer d contacts the third sublayer c, the third sublayer c is between the piezoelectric layer 3001 and the fourth sublayer d, the third sublayer c includes a fifth edge and a sixth edge opposite to the fifth edge in the horizontal direction, the fourth sublayer d includes a seventh edge and an eighth edge opposite to the seventh edge in the horizontal direction, the sixth edge is in a down-slope shape, the eighth edge is inside the sixth edge, the fifth edge is aligned with the seventh edge, and the size of the fourth sublayer d is smaller than the size of the third sublayer c; a second electrode extension 3007 on the second side 3003, contacting the piezoelectric layer 3001, and connected to the fifth edge and the seventh edge; a region where the first sublayer a, the third sublayer c, and the piezoelectric layer 3001 overlap is a resonance region 3100, wherein the first edge vertically corresponds to the fifth edge and the seventh edge, and the sixth edge vertically corresponds to the fourth edge and the second edge; the first electrode extension layer 3005 and the second electrode extension layer 3007 are located outside the resonance region 3100 without an overlapping portion; a first passivation layer 3008 on the first side 3002, the first passivation layer 3008 inside the resonant region 3100 covering the first electrode layer 3004, the first passivation layer 3008 outside the resonant region 3100 covering the piezoelectric layer 3001 outside the first edge, the first passivation layer 3008 outside the resonant region 3100 further covering the first electrode extension layer 3005 outside the second edge and the fourth edge; a second passivation layer 3009 on the second side 3003, the second passivation layer 3009 on the inner side of the resonance region 3100 covering the second electrode layer 3006, the second passivation layer 3009 on the outer side of the resonance region 3100 covering the second electrode extension layer 3007 on the outer side of the fifth and seventh edges, the second passivation layer 3009 on the outer side of the resonance region 3100 further covering the piezoelectric layer 3001 on the outer side of the sixth edge; a first overlap layer 3010 on the first side 3002 and contacting the first passivation layer 3008, where the first overlap layer 3010 includes a first raised portion (not labeled) and a first extended portion (not labeled), the first raised portion is raised with respect to the first extended portion, the first raised portion is located inside the resonance area 3100 and has a first overlapping portion overlapping with the first edge side, the first overlapping portion extends to the third edge along the horizontal direction, the first raised portion and the first electrode layer 3004 are located on both sides of the first passivation layer 3008, the first extended portion is located outside the resonance area 3100 and located outside the first edge without overlapping with the first electrode layer 3004, and the first extended portion and the piezoelectric layer 3001 are located on both sides of the first passivation layer 3008; a second strap layer 3011 on the second side 3003 and contacting the second passivation layer 3009, where the second strap layer 3011 includes a second raised portion (not labeled) and a second extending portion (not labeled), the second raised portion is raised relative to the second extending portion, the second raised portion is located inside the resonant area 3100 and has a second overlapping portion overlapping with the sixth edge side, the second overlapping portion extends to the eighth edge along the horizontal direction, the second raised portion and the second electrode layer 3006 are located on two sides of the second passivation layer 3009, the second extending portion is located outside the resonant area 3100 and located outside the sixth edge without overlapping with the second electrode layer 3006, and the second extending portion and the piezoelectric layer 3001 are located on two sides of the second passivation layer 3009.
In this embodiment, the material of the piezoelectric layer 3001 includes, but is not limited to, one of the following: aluminum nitride, aluminum nitride alloy, gallium nitride, zinc oxide, lithium tantalate, lithium niobate, lead zirconate titanate (PZT), lead magnesium niobate-lead titanate.
In this embodiment, the piezoelectric layer 3001 is a flat layer, and the piezoelectric layer 3001 includes a plurality of crystal grains including a first crystal grain and a second crystal grain, where the first crystal grain and the second crystal grain are any two crystal grains of the plurality of crystal grains. Those skilled in the art know that the crystal orientation, crystal plane, etc. of the crystal grain can be expressed based on a coordinate system. As shown in fig. 7, the hexagonal crystal grains, for example, aluminum nitride crystal grains, are represented by an ac three-dimensional coordinate system (including a-axis and c-axis). As shown in fig. 8, crystal grains of (i) orthorhombic system (a ≠ b ≠ c), (ii) tetragonal system (a = b ≠ c), and (iii) cubic system (a = b = c) are expressed by an xyz stereo coordinate system (including x-axis, y-axis, and z-axis). In addition to the above two examples, the die may also be represented based on other coordinate systems known to those skilled in the art, and thus the present invention is not limited by the above two examples.
In this embodiment, the first die may be represented based on a first stereo coordinate system, and the second die may be represented based on a second stereo coordinate system, where the first stereo coordinate system at least includes a first coordinate axis along a first direction and a third coordinate axis along a third direction, and the second stereo coordinate system at least includes a second coordinate axis along a second direction and a fourth coordinate axis along a fourth direction, where the first coordinate axis corresponds to a height of the first die, and the second coordinate axis corresponds to a height of the second die.
In this embodiment, the first direction and the second direction are the same or opposite. It should be noted that the first direction and the second direction are the same: the included angle range of the vector along the first direction and the vector along the second direction comprises 0 degree to 5 degrees; the first direction and the second direction are opposite to each other: an included angle range of a vector along the first direction and a vector along the second direction includes 175 degrees to 180 degrees.
In another embodiment, the first stereo coordinate system is an ac stereo coordinate system, wherein the first coordinate axis is a first c-axis, and the third coordinate axis is a first a-axis; the second three-dimensional coordinate system is an ac three-dimensional coordinate system, the second coordinate axis is a second c-axis, the fourth coordinate axis is a second a-axis, and the first c-axis and the second c-axis are directed in the same direction or in opposite directions.
In another embodiment, the first stereoscopic coordinate system further comprises a fifth coordinate axis along a fifth direction, and the second stereoscopic coordinate system further comprises a sixth coordinate axis along a sixth direction. In another embodiment, the first direction and the second direction are the same or opposite, and the third direction and the fourth direction are the same or opposite. It should be noted that the third direction and the fourth direction are the same: the included angle range of the vector along the third direction and the vector along the fourth direction comprises 0 degree to 5 degrees; the third direction and the fourth direction are opposite to each other: an included angle range of a vector along the third direction and a vector along the fourth direction includes 175 degrees to 180 degrees.
In another embodiment, the first stereo coordinate system is an xyz stereo coordinate system, wherein the first coordinate axis is a first z-axis, the third coordinate axis is a first y-axis, and the fifth coordinate axis is a first x-axis; the second three-dimensional coordinate system is an xyz three-dimensional coordinate system, the second coordinate axis is a second z axis, the fourth coordinate axis is a second y axis, and the sixth coordinate axis is a second x axis. In another embodiment, the first and second z-axes are pointing in the same direction, and the first and second y-axes are pointing in the same direction. In another embodiment, the first and second z-axes are oppositely directed and the first and second y-axes are oppositely directed. In another embodiment, the first and second z-axes are pointing in the same direction, and the first and second y-axes are pointing in opposite directions. In another embodiment, the first and second z-axes are oppositely directed, and the first and second y-axes are equally directed.
In this embodiment, the piezoelectric layer 3001 includes a plurality of crystal grains, and a half-width of a rocking curve of a crystal formed by the plurality of crystal grains is less than 2.5 degrees. It should be noted that a Rocking curve (Rocking curve) describes the angular divergence size of a specific crystal plane (a crystal plane determined by a diffraction angle) in a sample, and is represented by a planar coordinate system, wherein an abscissa is an included angle between the crystal plane and the sample plane, an ordinate represents the diffraction intensity of the crystal plane at a certain included angle, the Rocking curve is used for representing the crystal quality, and the smaller the half-peak width angle is, the better the crystal quality is. Further, the Full Width at Half Maximum (FWHM) refers to the distance between two points in one peak of the function, the front and rear function values of which are equal to Half of the peak value.
In this embodiment, the material of the first electrode layer 3004 includes, but is not limited to, at least one of: molybdenum, ruthenium, tungsten, platinum, iridium, aluminum, beryllium, and the material of the first electrode extension layer 3005 includes but is not limited to at least one of: molybdenum, ruthenium, tungsten, platinum, iridium, aluminum, beryllium, copper, gold. In this embodiment, the material of the first electrode layer 3004 is the same as the material of the first electrode extension layer 3005. In this embodiment, the material of the first sub-layer a is the same as the material of the second sub-layer b. In this embodiment, the thickness of the first sub-layer a is greater than 1 nm.
In this embodiment, the material of the second electrode layer 3006 includes, but is not limited to, at least one of the following: molybdenum, ruthenium, tungsten, platinum, iridium, aluminum, beryllium, copper, gold, and the material of the second electrode extension layer 3007 includes but is not limited to at least one of: molybdenum, ruthenium, tungsten, platinum, iridium, aluminum, beryllium, copper and gold. In this embodiment, the material of the second electrode layer 3006 is the same as the material of the second electrode extension layer 3007. In this embodiment, the material of the third sublayer c is the same as the material of the fourth sublayer d. In this embodiment, the thickness of the third sub-layer c is greater than 1 nm.
In another embodiment, the material of the electrode layer and the material of the electrode extension layer may be different.
In this embodiment, the material of the first passivation layer 3008 includes, but is not limited to, one of the following: silicon dioxide, silicon oxynitride, silicon oxycarbide, silicon nitride, titanium oxide, aluminum oxide, hafnium silicate, zirconium silicate, hafnium dioxide, zirconium dioxide. In this embodiment, the material of the second passivation layer 3009 includes, but is not limited to, one of the following: silicon dioxide, silicon oxynitride, silicon oxycarbide, silicon nitride, titanium oxide, aluminum oxide, hafnium silicate, zirconium silicate, hafnium dioxide, zirconium dioxide. In this embodiment, the material of the first passivation layer 3008 is the same as the material of the second passivation layer 3009. In another embodiment, the material of the first passivation layer (e.g., the first passivation layer 3008) and the material of the second passivation layer (e.g., the second passivation layer 3009) may be different.
In this embodiment, the material of the first strap layer 3010 includes, but is not limited to, at least one of the following: molybdenum, ruthenium, tungsten, platinum, iridium, aluminum, beryllium, copper and gold. In this embodiment, the material of the first butt-strap layer 3010 is the same as the material of the electrode 3004.
In this embodiment, the material of the second lap layer 3011 includes, but is not limited to, at least one of the following: molybdenum, ruthenium, tungsten, platinum, iridium, aluminum, beryllium, copper, gold. In this embodiment, the material of the second strap layer 3011 is the same as the material of the electrode 3006.
In another embodiment, the material of the overlap layer may be different from the material of the electrode layer, for example, the material of the overlap layer is tungsten or platinum, and the material of the electrode layer is molybdenum.
In another embodiment, the bead layer includes a first bead layer and a second bead layer, the first bead layer contacts the passivation layer, the second bead layer contacts the first bead layer, the second bead layer and the passivation layer are located on two sides of the first bead layer, the first bead layer is made of a material different from that of the second bead layer, for example, the first bead layer is made of molybdenum, and the second bead layer is made of platinum or tungsten.
In this embodiment, the bulk acoustic wave resonator 3000 further includes: a first passive structure 3012 on the first side 3002 and contacting the first edge of the first sublayer a, the third edge of the second sublayer b, and the piezoelectric layer 3001 outside the first edge, the first passive structure 3012 comprising the first overlap layer 3010 and a first passivation (not labeled) on the first passivation layer 3008 coincident with the first overlap layer 3010; and a second passive structure 3013 on the second side 3003 and contacting the sixth edge of the third sublayer c, the eighth edge of the fourth sublayer d, and the piezoelectric layer 3001 outside the sixth edge, wherein the second passive structure 3013 includes a second passivation portion (not labeled) on the second overlap layer 3011 and the second passivation layer 3009 and overlapping the second overlap layer 3011. The passivation portion includes a dielectric material, and the electrode layer and the overlap layer are electrically isolated from each other and are not electrically connected to each other, so that the overlap layer is passive, and a combined structure of the passivation portion and the overlap layer is also passive.
In this embodiment, a first thickness of the first passive structure 3012 (i.e., a sum of thicknesses of the first strap layer 3010 and the first passivation layer 3008) is less than a thickness of the first electrode layer 3004, a second thickness of the second passive structure 3013 (i.e., a sum of thicknesses of the second strap layer 3011 and the second passivation layer 3009) is less than a thickness of the second electrode layer 3006, and the first thickness is equal to or approximately equal to the second thickness.
In this embodiment, the first width of the first raised portion matches a primary mode of transverse acoustic waves generated by the resonance region 3100, such as the rayleigh S1 mode (1) st order systematic mode), or TE1 mode (1) st order Thickness Extension mode) (e.g., the first width is equal to an integer multiple of one-half wavelength), a second width of the second raised portion matches an acoustic wavelength of a primary mode of transverse acoustic waves generated by the resonant region 3100 (e.g., the second width is equal to an integer multiple of one-half wavelength), and the first width is equal to or approximately equal to the second width. It should be noted that the first raised portion and the second raised portion are used for matching acoustic impedances of the resonance region and the attenuation region, so that more sound waves generated by the resonance region propagate into the attenuation region.
In this embodiment, the first sub-layer a is located on one side of the first raised portion in the vertical direction, and the second sub-layer b is located on one side of the first raised portion in the horizontal direction. In this embodiment, the third sub-layer c is located on one side of the second raised portion in the vertical direction, and the fourth sub-layer d is located on one side of the second raised portion in the horizontal direction.
In this embodiment, a third thickness of the first extension portion (i.e., a thickness of a portion of the first tab layer 3010 located outside the resonance region 3100) is smaller than a thickness of the first electrode layer 3004, a fourth thickness of the second extension portion (i.e., a thickness of a portion of the second tab layer 3011 located outside the resonance region 3100) is smaller than a thickness of the second electrode layer 3006, and the third thickness is equal to or approximately equal to the fourth thickness.
In this embodiment, an overlapping region of the first extension portion, the second electrode extension layer 3007 and the piezoelectric layer 3001 is an attenuation region 3200; an area where the second extension portion, the first electrode extension layer 3005, and the piezoelectric layer 3001 overlap is an attenuation region 3300; a second cutoff frequency of the attenuation region 3200 matches (e.g., is equal to or less than) the first cutoff frequency of the resonance region 3100, a third cutoff frequency of the attenuation region 3300 matches (e.g., is equal to or less than) the first cutoff frequency of the resonance region 3100, and the second cutoff frequency is equal to or approximately the third cutoff frequency.
It should be noted that the cut-off frequency of the attenuation region is matched with (e.g., equal to or less than) the cut-off frequency of the resonance region, so that the sound wave entering the attenuation region is in an attenuation mode (evanescent mode), that is, the wave number (wave number) in the attenuation region only contains an imaginary part, so that the sound wave is exponentially attenuated. To more clearly illustrate the beneficial effects of embodiments of the present invention, see multiple dispersion curves (dispersion curves) 600 of fig. 9. The horizontal axis of the dispersion curve coordinate system represents the wave number, the vertical axis represents the frequency, the origin of the coordinate system represents the wave number as 0, the left side of the origin represents that the wave number only contains an imaginary part, and the right side of the origin represents that the wave number only contains a real part. As shown in fig. 9, a first dispersion curve 601 represents a dispersion relation (dispersion relation) of a resonance region, an intersection of the first dispersion curve 601 and a vertical axis represents a first cut-off frequency 602 of the resonance region, a second dispersion curve 603 represents a dispersion relation of an attenuation region, an intersection of the second dispersion curve 603 and the vertical axis represents a second cut-off frequency 604 of the attenuation region, and the second cut-off frequency 604 is smaller than the first cut-off frequency 602. Referring again to FIG. 9, for the parallel resonant frequency f p The wavenumber of the first dispersion curve 601 only includes a real part, and the wavenumber of the second dispersion curve 603 only includes an imaginary part, so that the sound wave is in an attenuation mode after propagating from the resonance region into the attenuation region, and the sound wave is exponentially attenuated; specifically, the expression for acoustic wave displacement includes exp (-jkx), where the wave number k contains only imaginary components.
FIG. 10 shows two parallel impedance curves, where the abscissa represents relative frequency and the ordinate represents relative frequencyThe coordinates represent relative parallel impedance values representing the ratio of the absolute parallel impedance value to a specific parallel impedance value, e.g., 300 ohms for an absolute parallel impedance value and 500 ohms for a specific parallel impedance value, then 0.6 (300/500) for the relative parallel impedance value. Referring to fig. 10, a first parallel impedance curve 701 represents the relative parallel impedance curve of a bulk acoustic wave resonator device that does not include a passive structure, and a second parallel impedance curve 703 represents the relative parallel impedance curve of a bulk acoustic wave resonator device that does include a passive structure. As shown in fig. 10, for the parallel resonance frequency f p The corresponding value on the second parallel impedance curve 703 is greater than the corresponding value on the first parallel impedance curve 701. It should be noted that the passive structure can attenuate the laterally propagated sound waves generated in the resonance region, suppress the parasitic edge modes, and increase the Z-dimension p And corresponding Q values. Furthermore, the passive structures are not electrically connected to the electrode layers, so that the passive structures are paired with Kt 2 The influence of (c) is small.
Fig. 11 shows a plurality of parallel impedance curves 800, wherein the abscissa represents relative frequency and the ordinate represents relative parallel impedance values. Referring to fig. 11, a third parallel impedance curve 801 corresponds to a structure 1, a fourth parallel impedance curve 803 corresponds to a structure 2, and a fifth parallel impedance curve 805 corresponds to a structure 3, wherein a first raised portion of the structure 1 is located on an electrode layer, second and third raised portions of the structures 2 and 3 are embedded in the electrode layer, the thickness of the second raised portion is similar to the thickness of the third raised portion, the thickness of the third raised portion is closer to the thickness of a sub-layer of the electrode layer on the horizontal direction side, and the thickness of the second raised portion is different from the thickness of a sub-layer of the electrode layer on the horizontal direction side. For parallel resonance frequency f p The corresponding value on the fifth parallel impedance curve 805 is greater than the corresponding value on the fourth parallel impedance curve 803, and the corresponding value on the fourth parallel impedance curve 803 is greater than the corresponding value on the third parallel impedance curve 801. The thickness of the raised portion is matched to the thickness of the sub-layers (e.g., the second sub-layer b and the fourth sub-layer d) of the electrode layer on the horizontal side, that is, the thickness of the raised portion and the sub-layersThe thickness of the dielectric layer is similar, so that the continuity of sound waves which are transmitted from the resonance region to the attenuation region can be improved, the parasitic resonance generated in the transmission process is reduced, and the parallel impedance Z is further improved p And the corresponding Q value.
In this embodiment, the bulk acoustic wave resonator 3000 further includes: a cavity 3014, the first electrode layer 3004 being located in the cavity 3014, one end of the first electrode extension layer 3005 being located in the cavity 3014, and the first passive structure 3012 being located in the cavity 3014. In another embodiment, a lower electrode layer (e.g., the first electrode layer 3004) may be located over a cavity, covering the cavity; and the passive structure corresponding to the lower electrode layer is positioned outside the cavity.
Fig. 4 is a schematic structural diagram of a section B of a bulk acoustic wave resonator 3000 according to an embodiment of the present invention.
As shown in fig. 4, the bulk acoustic wave resonator device 3000 includes: the piezoelectric layer 3001, the first side 3002 and the second side 3003 included in the piezoelectric layer 3001; the first electrode layer 3004 is located on the first side 3002, and contacts the piezoelectric layer 3001, the first electrode layer 3004 includes the first sublayer a and the second sublayer b, the first sublayer a contacts the piezoelectric layer 3001, the second sublayer b contacts the first sublayer a, the first sublayer a is located between the piezoelectric layer 3001 and the second sublayer b, the first sublayer a further includes a ninth edge and a tenth edge opposite to the ninth edge in a horizontal direction, the ninth edge is in a downhill shape, the tenth edge is in a downhill shape, the second sublayer b further includes an eleventh edge and a twelfth edge opposite to the eleventh edge in a horizontal direction, the eleventh edge is in a downhill shape, the twelfth edge is in a downhill shape, the eleventh edge is located inside the ninth edge, the twelfth edge is located inside the tenth edge, and the size of the second sublayer b is smaller than the size of the first sublayer a; the second electrode layer 3006, located on the second side 3003, contacts the piezoelectric layer 3001, the second electrode layer 3006 includes the third sublayer c and the fourth sublayer d, the third sublayer c contacts the piezoelectric layer 3001, the fourth sublayer d contacts the third sublayer c, the third sublayer c is located between the piezoelectric layer 3001 and the fourth sublayer d, the third sublayer c further includes a thirteenth edge and a fourteenth edge opposite to the thirteenth edge in the horizontal direction, the thirteenth edge is in a downslope shape, the fourteenth edge is in a downslope shape, the fourth sublayer d includes a fifteenth edge and a sixteenth edge opposite to the fifteenth edge in the horizontal direction, the fifteenth edge is in a downslope shape, the fifteenth edge is located inside the thirteenth edge, the sixteenth edge is located inside the fourteenth edge, and the size of the fourth sublayer d is smaller than the size of the third sublayer c; within the resonance region 3100, the ninth edge vertically corresponds to the thirteenth edge, the tenth edge vertically corresponds to the fourteenth edge, the eleventh edge vertically corresponds to the fifteenth edge, and the twelfth edge vertically corresponds to the sixteenth edge; the first passivation layer 3008 on the first side 3002, the first passivation layer 3008 on the inner side of the resonance region 3100 covering the first electrode layer 3004, the first passivation layer 3008 on the outer side of the resonance region 3100 further covering the piezoelectric layer 3001 on the outer side of the ninth edge, the first passivation layer 3008 on the outer side of the resonance region 3100 further covering the piezoelectric layer 3001 on the outer side of the tenth edge; the second passivation layer 3009 on the second side 3003, the second passivation layer 3009 on the inner side of the resonance region 3100 covering the second electrode layer 3006, the second passivation layer 3009 on the outer side of the resonance region 3100 further covering the piezoelectric layer 3001 on the outer side of the thirteenth edge, the second passivation layer 3009 on the outer side of the resonance region 3100 further covering the piezoelectric layer 3001 on the outer side of the fourteenth edge; the first overlap layer 3010 is located on the first side 3002 and contacts the first passivation layer 3008, the first overlap layer 3010 includes the first raised portion and the first extended portion, the first raised portion is raised relative to the first extended portion, the first raised portion is located inside the resonant area 3100, the first raised portion further includes a third overlapping portion overlapping with the ninth edge side and a fourth overlapping portion overlapping with the tenth edge side, the third overlapping portion extends to the eleventh edge along the horizontal direction, the fourth overlapping portion extends to the twelfth edge along the horizontal direction, the first raised portion and the first electrode layer 3004 are located on both sides of the first passivation layer 3008, the first extended portion is located outside the resonant area 3100, the third overlapping portion is located outside the ninth edge and the tenth edge, the fourth overlapping portion is not overlapped with the first electrode layer 3004, and the first extended portion and the passivation layer 3001 are located on both sides of the first passivation layer 3008; the second overlap layer 3011 is located on the second side 3003 and contacts the second passivation layer 3009, the second overlap layer 3011 includes the second raised portion and the second extended portion, the second raised portion is raised relative to the second extended portion, the second raised portion is located inside the resonant region 3100, the second raised portion further includes a fifth overlapping portion overlapping with the thirteenth edge side and a sixth overlapping portion overlapping with the fourteenth edge side, the fifth overlapping portion extends to the fifteenth edge along the horizontal direction, the sixth overlapping portion extends to the sixteenth edge along the horizontal direction, the second raised portion and the second electrode layer 3006 are located on both sides of the second passivation layer 3009, the second extended portion is located on the outer side of the resonant region 3100 and also located on the outer side of the thirteenth edge and the outer side of the fourteenth edge, there is no overlapping portion with the second electrode layer 3006, and the second extended portion and the piezoelectric layer 3001 are located on both sides of the second passivation layer 3009.
In this embodiment, a region where the first extension portion, the second extension portion, and the piezoelectric layer 3001 overlap is an attenuation region 3400; the fourth cutoff frequency of the attenuation region 3400 matches (e.g., is equal to or less than) the first cutoff frequency of the resonance region 3100.
Fig. 5 is a schematic diagram of a first top-view structure of the bulk acoustic wave resonator 3000 based on the first electrode layer 3004 relative to the cross-section a according to the embodiment of the present invention.
As shown in fig. 5, the bulk acoustic wave resonator device 3000 includes: the first electrode layer 3004 (indicated by dashed lines), the first electrode layer 3004 having a hexagonal shape including the first edge, the second edge, the ninth edge, the tenth edge, the seventeenth edge, and the eighteenth edge; the first electrode extension layer 3005 connected to the second edge; the first lap layer 3010 has overlapping portions on a plurality of edge sides of the first electrode layer 3004, is adjacent to the first electrode extension layer 3005, and the first lap layer 3010 includes the first raised portion 3015 and the first extension portion 3016; wherein the first raised portion 3015 is located inside an edge of the first electrode layer 3004, and has an overlapping portion with the ninth edge side, the seventeenth edge side, the first edge side, the tenth edge side, and the eighteenth edge side; the second extending portion 3005 is located at the outer side of the ninth edge, the seventeenth edge, the first edge, the tenth edge, and the eighteenth edge, and does not overlap with the first electrode layer 3004.
In this embodiment, the width w of the first butt strap layer 3010 is the same for each edge, accordingly, the width of the first raised portion 3015 is the same for each edge, and the width of the first extending portion 3016 is the same for each edge.
In this embodiment, the first passive structure 3012 includes the first lap layer 3010 adjacent to the first electrode extension layer 3005. In this embodiment, the first passive structure 3012 includes the first raised portion 3015 and has an overlapping portion with the ninth edge side, the seventeenth edge side, the eighteenth edge side, the tenth edge side, and the tenth edge side. In this embodiment, the first passive structure 3012 further includes the first extending portion 3016 located outside the ninth edge, the seventeenth edge, the first edge, the tenth edge, and the eighteenth edge and having no overlapping portion with the first electrode layer 3004.
In this embodiment, the width w of the first passive structure 3012 corresponding to each edge is the same.
Fig. 6 is a second top view structure diagram of the bulk acoustic wave resonator device 3000 according to the embodiment of the present invention, based on the second electrode layer 3006, with respect to the cross section a.
As shown in fig. 6, the bulk acoustic wave resonator device 3000 includes: the second electrode layer 3006 (shown by dotted lines), the second electrode layer 3006 having a hexagonal shape including the fifth edge, the sixth edge, the thirteenth edge, the fourteenth edge, the nineteenth edge, and the twentieth edge; the second electrode extension layer 3007 connected to the fifth edge; the second lap layer 3011 having overlapping portions with a plurality of edge sides of the second electrode layer 3006 and being adjacent to the second electrode extension layer 3007, the second lap layer 3011 including the second raised portion 3017 and the second extension portion 3018; wherein the second raised portion 3017 is located inside an edge of the second electrode layer 3006 and has an overlapping portion with the thirteenth edge side, the nineteenth edge side, the sixth edge side, the fourteenth edge side, and the twentieth edge side; the second extending portion 3018 is located at the outer side of the thirteenth edge, the nineteenth edge, the sixth edge, the fourteenth edge, and the twentieth edge, and has no overlapping portion with the second electrode layer 3006.
In this embodiment, the width w of the second butt strap layer 3011 is the same for each edge, accordingly, the width of the second raised portion 3017 is the same for each edge, and the width of the second extending portion 3018 is the same for each edge.
In this embodiment, the second passive structure 3013 includes the second lap layer 3011 adjacent to the second electrode extension layer 3007. In this embodiment, the second passive structure 3013 includes the second raised portion 3017 and has an overlapping portion with the thirteenth edge side, the nineteenth edge side, the sixth edge side, the fourteenth edge side, and the twentieth edge side. In this embodiment, the second passive structure 3013 further includes a second extending portion 3018 located outside the thirteenth edge, the nineteenth edge, the sixth edge, the fourteenth edge, and the twentieth edge and having no overlapping portion with the second electrode layer 3006.
In this embodiment, the width w of the second passive structure 3013 is the same for each edge.
In this embodiment, the first and second passive structures 3012 and 3013 surround the first and second electrode layers 3004 and 3006, i.e., surround the resonant region 3100.
It should be noted that, in the embodiment of the present invention, the top view of the electrode layer is a hexagon, so the present invention is not limited to the specific embodiment disclosed below, and the top view of the electrode layer may be other polygons (for example, pentagon, heptagon), ellipse, and the like.
In another embodiment, the bulk acoustic wave resonator includes a plurality of electrode extension layers respectively connected to a plurality of edges of the electrode layer, and the passive structure corresponding to the electrode layer is adjacent to the plurality of electrode extension layers and has a passive overlap with other edges than the plurality of edges, and the passive structure further includes a passive extension portion located outside the other edges.
In another embodiment, the bulk acoustic wave resonator device includes three or more passive structures surrounding a resonance region of the bulk acoustic wave resonator device.
Fig. 12 to 15 show one embodiment of the bulk acoustic wave resonator device of the present invention, but the present invention can be implemented in other ways than those described herein, and thus the present invention is not limited to the embodiments disclosed below. Fig. 12 is a schematic diagram of a first cross-sectional structure of the bulk acoustic wave resonator device and a sound velocity distribution diagram of a corresponding region, fig. 13 is a schematic diagram of a second cross-sectional structure of the bulk acoustic wave resonator device, fig. 14 is a schematic diagram of a first top-view structure of a first electrode layer of the bulk acoustic wave resonator device relative to the first cross-section, and fig. 15 is a schematic diagram of a second top-view structure of a second electrode layer of the bulk acoustic wave resonator device relative to the first cross-section.
In this embodiment, the bulk acoustic wave resonator device 3000 is described in the following with reference to the cross-sectional a structure (fig. 3) of the bulk acoustic wave resonator device 3000, and the difference between this embodiment and the above embodiment is: the bulk acoustic wave resonator device 3000 further includes: a third passivation and a surrounding groove in the third passivation. The following detailed description will be made in conjunction with the accompanying drawings.
As shown in fig. 12 to 15, the bulk acoustic wave resonator device 3000 further includes: a third passivation portion (not labeled) on the second side 3003 and contacting the second electrode layer 3006; a surrounding groove 3019 in the third passivation, inside the resonant region 3100, inside the second raised portion, and adjacent to the second raised portion.
In this embodiment, the surrounding type groove 3019 is polygonal. In other embodiments, the circumferential groove may also be circular or elliptical.
Note that the second passivation layer 3009 includes the third passivation portion and the second passivation portion.
In this embodiment, the surrounding groove 3019, the first section I formed by the surrounding groove 3019, and the second section II formed by the first raised portion and the second raised portion are added inside the resonance region 3100. By setting the cutoff frequency of the first section region I to be higher than the cutoff frequency of the intermediate portion (not labeled) of the resonance region 3100 inside the surrounding groove 3019 and setting the cutoff frequency of the second section region II to be lower than the cutoff frequency of the intermediate portion, a piston mode (piston mode) is formed, see fig. 12, which shows a sound velocity distribution diagram in a piston mode where the sound velocity is proportional to the cutoff frequency, and the piston mode is excited to suppress the higher-order spurious modes of the transverse sound wave, as shown in fig. 33, and the series resonance frequency (f) is reduced s ) Near and less than f s Clutter of the portion (c).
To more clearly illustrate the benefits of embodiments of the present invention, referring to FIG. 16, three exemplary second Type (Type II) sonic dispersion curves (Curve 1, curve 2, and Curve 3 in FIG. 16) are shown. The horizontal axis of the dispersion curve coordinate system represents the wave number, the vertical axis represents the frequency, the origin of the coordinate system represents the wave number as 0, the left side of the origin represents that the wave number only contains an imaginary part, and the right side of the origin represents that the wave number only contains a real part. As shown in fig. 16, a first dispersion curve (curve 1 in fig. 16) represents the middle of the resonance regionDispersion relation (dispersion relation), an intersection of the first dispersion curve and the vertical axis represents a first cut-off frequency of the resonance region (a in fig. 16); a second dispersion curve (curve 2 in fig. 16) represents the dispersion relation of the first section I, and the intersection point of the second dispersion curve and the vertical axis represents a second cut-off frequency (b in fig. 16) of the first section I, which is greater than the first cut-off frequency; a third dispersion curve (curve 3 in fig. 16) represents the dispersion relation of the second section region II, and an intersection of the third dispersion curve and the vertical axis represents a third cutoff frequency (c in fig. 16) of the second section region II, which is smaller than the first cutoff frequency. Referring again to FIG. 16, for the series resonant frequency (straight line f in FIG. 16) s ) The wave number of the first dispersion curve is 0 and is a resonance mode, the wave number of the second dispersion curve only contains a real part, so that a standing wave is formed by a high-order parasitic mode of the transverse sound wave in a first section region I, the propagation of the transverse sound wave in a resonance region and a second section region II can be transited, the wave number of the third dispersion curve only contains an imaginary part, and the high-order parasitic mode of the transverse sound wave is an attenuation mode after propagating from the first section region I to the second section region II, specifically, the expression of the displacement of the transverse sound wave includes exp (-jkx), and the wave number k only contains an imaginary part.
Fig. 33 shows two series admittance curves, where the abscissa represents frequency, the ordinate represents relative series admittance values, and the relative series admittance values represent the ratio of the absolute series admittance value to a specific series admittance value, e.g., 1 siemens for the absolute series admittance value and 2 siemens for the specific series admittance value, and 0.5 (1/2) for the relative series admittance value. Referring to fig. 33, a first series admittance curve (curve 1 in fig. 33) represents a relative series admittance curve of the bulk acoustic wave resonator device excluding the surround-type groove 3019 and the passive structure, and a second series admittance curve (curve 2 in fig. 33) represents a relative series admittance curve of the bulk acoustic wave resonator device including the surround-type groove 3019 and the passive structure. As shown in fig. 33, for the series resonance frequency f s Near and less than f s The corresponding ripple on the second series admittance curve is smaller than the first series admittance curveThe corresponding ripple on the admittance curve. It should be noted that the surrounding type groove 3019 and the passive structure may form a piston mode in the resonance region 3100, suppress a high-order parasitic mode of a transverse acoustic wave, improve resonator performance, and reduce an in-band ripple.
Fig. 17 shows one embodiment of the bulk acoustic wave resonator device of the present invention, but the present invention can be implemented in other ways than those described herein, and thus the present invention is not limited to the embodiments disclosed below. Fig. 17 is a first cross-sectional structure diagram of the bulk acoustic wave resonator device and a sound velocity distribution diagram of a corresponding region.
In this embodiment, the bulk acoustic wave resonator device 3000 is explained in addition to the cross-sectional a structure (fig. 3) of the bulk acoustic wave resonator device in the above-described embodiment, and the difference between this embodiment and the above-described embodiment is that: the bulk acoustic wave resonator device 3000 further includes: a third passivation and a surrounding groove in the third passivation. The following detailed description will be made in conjunction with the accompanying drawings.
As shown in fig. 17, the bulk acoustic wave resonator device 3000 further includes: a third passivation portion (not labeled) on the first side 3002 and contacting the first electrode layer 3004; a surrounding groove 3019 in the third passivation, inside the resonance region 3100, inside the first raised portion, and adjacent to the first raised portion.
In this embodiment, the surrounding type groove 3019 is polygonal. In other embodiments, the circumferential groove may also be circular or elliptical.
Note that the first passivation layer 3008 includes the third passivation portion and the first passivation portion.
In this embodiment, the surrounding groove 3019, the first section I formed by the surrounding groove 3019, and the second section II formed by the first raised portion and the second raised portion are added inside the resonance region 3100. By arranging for the cut-off frequency of the first section I to be greater than that of the middle portion (not labeled) of the resonance region 3100 inside the surrounding-type groove 3019A cut-off frequency is set to be lower than the cut-off frequency of the middle part in the second section region II, a piston mode (piston mode) is formed, referring to fig. 17, a sound velocity distribution diagram in the piston mode is shown, the sound velocity is proportional to the cut-off frequency, the piston mode can be excited to suppress the higher order parasitic mode of the transverse sound wave, as shown in fig. 33, and the series resonance frequency (f) is reduced s ) Near and less than f s Of the portion (c).
Fig. 18 and 19 show one embodiment of the bulk acoustic wave resonator device of the present invention, but the present invention may be practiced in other ways than those described herein, and thus the present invention is not limited to the embodiments disclosed below. Wherein, fig. 18 is a first cross-sectional structural diagram of the bulk acoustic wave resonance device, and fig. 19 is a second cross-sectional structural diagram of the bulk acoustic wave resonance device.
Fig. 18 is a schematic structural view of a cross section a of a bulk acoustic wave resonator 9000 according to an embodiment of the present invention.
As shown in fig. 18, the bulk acoustic wave resonator 9000 includes: a piezoelectric layer 9001, the piezoelectric layer 9001 comprising a first side 9002 and a second side 9003 vertically opposing the first side 9002; a first electrode layer 9004 located at the first side 9002 and contacting the piezoelectric layer 9001, wherein the first electrode layer 9004 comprises a first sublayer a and a second sublayer b, the first sublayer a contacts the piezoelectric layer 9001, the second sublayer b contacts the first sublayer a, the first sublayer a is located between the piezoelectric layer 9001 and the second sublayer b, the first sublayer a comprises a first edge and a second edge opposite to the first edge in a horizontal direction, the second sublayer b comprises a third edge and a fourth edge opposite to the third edge in a horizontal direction, the first edge is in a downhill shape, the third edge is located inside the first edge, the fourth edge is aligned with the second edge, and the size of the second sublayer b is smaller than that of the first sublayer a; a first electrode extension layer 9005 at the first side 9002 contacting the piezoelectric layer 9001, connecting the second edge and the fourth edge; a second electrode layer 9006 located on the second side 9003 and contacting the piezoelectric layer 9001, wherein the second electrode layer 9006 includes a third sublayer c and a fourth sublayer d, the third sublayer c contacts the piezoelectric layer 9001, the fourth sublayer d contacts the third sublayer c, the third sublayer c is located between the piezoelectric layer 9001 and the fourth sublayer d, the third sublayer c includes a fifth edge and a sixth edge opposite to the fifth edge in the horizontal direction, the fourth sublayer d includes a seventh edge and an eighth edge opposite to the seventh edge in the horizontal direction, the sixth edge is in a down-slope shape, the eighth edge is located inside the sixth edge, the fifth edge is aligned with the seventh edge, and the size of the fourth sublayer d is smaller than that of the third sublayer c; a second electrode extension layer 9007 at the second side 9003 contacting the piezoelectric layer 9001 connecting the fifth edge and the seventh edge; the overlapping area of the first sublayer a, the third sublayer c and the piezoelectric layer 9001 is a resonance area 9100, wherein the first edge vertically corresponds to the fifth edge and the seventh edge, and the sixth edge vertically corresponds to the fourth edge and the second edge; the first electrode extension 9005 and the second electrode extension 9007 are located outside the resonance region 9100 without an overlapping portion; a first passivation layer 9008 on the first side 9002, the first passivation layer 9008 inside the resonance region 9100 covering the first electrode layer 9004, the first passivation layer 9008 outside the resonance region 9100 covering the first electrode extension layer 9005 outside the second and fourth edges; a second passivation layer 9009 on the second side 9003, the second passivation layer 9009 inside the resonance region 9100 covering the second electrode layer 9006, the second passivation layer 9009 outside the resonance region 9100 covering the second electrode extension layer 9007 outside the fifth and seventh edges; a first overlap layer 9010 located on the first side 9002 and contacting the first passivation layer 9008, wherein the first overlap layer 9010 includes a first raised portion (not labeled) and a first extended portion (not labeled), the first raised portion is raised relative to the first extended portion, the first raised portion is located inside the resonance region 9100 and has a first overlapping portion overlapping with the first edge side, the first overlapping portion extends to the third edge along the horizontal direction, the first raised portion and the first electrode layer 9004 are located on two sides of the first passivation layer 9008, the first extended portion is located outside the resonance region 9100 and is located outside the first edge and has no overlapping portion with the first electrode layer 9004, and a first empty slot 9015 is included between the first extended portion and the piezoelectric layer 9001; a second overlap layer 9011 located on the second side 9003 and contacting the second passivation layer 9009, wherein the second overlap layer 9011 includes a second raised portion (not labeled) and a second extended portion (not labeled), the second raised portion is raised with respect to the second extended portion, the second raised portion is located inside the resonance region 9100 and has a second overlapping portion overlapping with the sixth edge side, the second overlapping portion extends to the eighth edge along the horizontal direction, the second raised portion and the second electrode layer 9006 are located on both sides of the second passivation layer 9009, the second extended portion is located outside the resonance region 9100 and is located outside the sixth edge without overlapping with the second electrode layer 9006, and a second empty groove 9016 is included between the second extended portion and the piezoelectric layer 9001.
In this embodiment, the material of the piezoelectric layer 9001 includes, but is not limited to, one of the following: aluminum nitride, aluminum nitride alloy, gallium nitride, zinc oxide, lithium tantalate, lithium niobate, lead zirconate titanate, lead magnesium niobate-lead titanate.
In this embodiment, the piezoelectric layer 9001 is a flat layer, and the piezoelectric layer 9001 comprises a plurality of grains including a first grain and a second grain, wherein the first grain and the second grain are any two grains of the plurality of grains. Those skilled in the art know that the crystal orientation, crystal plane, etc. of the crystal grain can be expressed based on a coordinate system.
In this embodiment, the first die may be represented based on a first stereo coordinate system, and the second die may be represented based on a second stereo coordinate system, where the first stereo coordinate system at least includes a first coordinate axis along a first direction and a third coordinate axis along a third direction, and the second stereo coordinate system at least includes a second coordinate axis along a second direction and a fourth coordinate axis along a fourth direction, where the first coordinate axis corresponds to a height of the first die, and the second coordinate axis corresponds to a height of the second die.
In this embodiment, the first direction and the second direction are the same or opposite. It should be noted that the first direction and the second direction are the same: the included angle range of the vector along the first direction and the vector along the second direction comprises 0 degree to 5 degrees; the first direction and the second direction are opposite to each other: an included angle range of a vector along the first direction and a vector along the second direction includes 175 degrees to 180 degrees.
In another embodiment, the first stereo coordinate system is an ac stereo coordinate system, wherein the first coordinate axis is a first c-axis, and the third coordinate axis is a first a-axis; the second three-dimensional coordinate system is an ac three-dimensional coordinate system, the second coordinate axis is a second c-axis, the fourth coordinate axis is a second a-axis, and the first c-axis and the second c-axis are directed in the same direction or in opposite directions.
In another embodiment, the first stereoscopic coordinate system further comprises a fifth coordinate axis along a fifth direction, and the second stereoscopic coordinate system further comprises a sixth coordinate axis along a sixth direction. In another embodiment, the first direction and the second direction are the same or opposite, and the third direction and the fourth direction are the same or opposite. It should be noted that the third direction and the fourth direction are the same: the included angle range of the vector along the third direction and the vector along the fourth direction comprises 0 degree to 5 degrees; the third direction and the fourth direction are opposite to each other: an included angle range of a vector along the third direction and a vector along the fourth direction includes 175 degrees to 180 degrees.
In another embodiment, the first stereo coordinate system is an xyz stereo coordinate system, wherein the first coordinate axis is a first z-axis, the third coordinate axis is a first y-axis, and the fifth coordinate axis is a first x-axis; the second three-dimensional coordinate system is an xyz three-dimensional coordinate system, the second coordinate axis is a second z axis, the fourth coordinate axis is a second y axis, and the sixth coordinate axis is a second x axis. In another embodiment, the first and second z-axes are pointing in the same direction, and the first and second y-axes are pointing in the same direction. In another embodiment, the first and second z-axes are oppositely directed and the first and second y-axes are oppositely directed. In another embodiment, the first and second z-axes are pointing in the same direction, and the first and second y-axes are pointing in opposite directions. In another embodiment, the first and second z-axes are oppositely directed, and the first and second y-axes are identically directed.
In this embodiment, the piezoelectric layer 9001 comprises a plurality of grains forming a crystal having a rocking curve half-width below 2.5 degrees.
In this embodiment, the material of the first electrode layer 9004 includes, but is not limited to, at least one of the following: molybdenum, ruthenium, tungsten, platinum, iridium, aluminum, beryllium, the material of the first electrode extension layer 9005 includes but is not limited to at least one of: molybdenum, ruthenium, tungsten, platinum, iridium, aluminum, beryllium, copper, gold. In this embodiment, the material of the first electrode layer 9004 is the same as that of the first electrode extension layer 9005. In this embodiment, the material of the first sub-layer a is the same as the material of the second sub-layer b. In this embodiment, the thickness of the first sub-layer a is greater than 1 nm.
In this embodiment, the material of the second electrode layer 9006 includes, but is not limited to, at least one of the following: molybdenum, ruthenium, tungsten, platinum, iridium, aluminum, beryllium, and the material of the second electrode extension layer 9007 includes but is not limited to at least one of: molybdenum, ruthenium, tungsten, platinum, iridium, aluminum, beryllium, copper and gold. In this embodiment, the material of the second electrode layer 9006 is the same as the material of the second electrode extension layer 9007. In this embodiment, the material of the third sublayer c is the same as the material of the fourth sublayer d. In this embodiment, the thickness of the third sublayer c is greater than 1 nm.
In another embodiment, the material of the electrode layer and the material of the electrode extension layer may be different.
In this embodiment, the material of the first passivation layer 9008 includes but is not limited to one of the following: silicon dioxide, silicon oxynitride, silicon oxycarbide, silicon nitride, titanium oxide, aluminum oxide, hafnium silicate, zirconium silicate, hafnium dioxide, zirconium dioxide. In this embodiment, the material of the second passivation layer 9009 includes, but is not limited to, one of the following: silicon dioxide, silicon oxynitride, silicon oxycarbide, silicon nitride, titanium oxide, aluminum oxide, hafnium silicate, zirconium silicate, hafnium dioxide, zirconium dioxide. In this embodiment, the material of the first passivation layer 9008 is the same as the material of the second passivation layer 9009. In another embodiment, the material of the first passivation layer (e.g., the first passivation layer 9008) and the material of the second passivation layer (e.g., the second passivation layer 9009) may be different.
In this embodiment, the material of the first bordering layer 9010 includes, but is not limited to, at least one of the following: molybdenum, ruthenium, tungsten, platinum, iridium, aluminum, beryllium. In this embodiment, the material of the first butt-strap layer 9010 is the same as that of the electrode 9004.
In this embodiment, the material of the second lap layer 9011 includes, but is not limited to, at least one of the following: molybdenum, ruthenium, tungsten, platinum, iridium, aluminum, beryllium. In this embodiment, the material of the second border layer 9011 is the same as that of the electrode 9006.
In another embodiment, the material of the overlap layer and the electrode layer may be different, for example, the material of the overlap layer is tungsten or platinum, and the material of the electrode layer is molybdenum.
In another embodiment, the bead layer includes a first bead layer and a second bead layer, the first bead layer contacts the passivation layer, the second bead layer contacts the first bead layer, the second bead layer and the passivation layer are located on two sides of the first bead layer, the first bead layer is made of a material different from that of the second bead layer, for example, the material of the first bead layer on the passivation layer is molybdenum, and the material of the second bead layer on the first bead layer is platinum or tungsten.
In this embodiment, the bulk acoustic wave resonator 9000 further comprises: a first passive structure 9012 located on the first side 9002 and contacting the first edge of the first sublayer a, the third edge of the second sublayer b, and the piezoelectric layer 9001 outside the first edge, wherein the first passive structure 9012 includes a first passivation portion (not labeled) on the first overlap layer 9010 and the first passivation layer 9008 that overlaps with the first overlap layer 9010; and a second passive structure 9013, located on the second side 9003, and contacting the sixth edge of the third sublayer c, the eighth edge of the fourth sublayer d, and the piezoelectric layer 9001 outside the sixth edge, where the second passive structure 9013 includes the second ledge layer 9011 and a second passivation portion (not labeled) on the second passivation layer 9009 and overlapping with the second ledge layer 9011. The passivation portion includes a dielectric material, and the electrode layer and the overlap layer are electrically isolated from each other and are not electrically connected to each other, so that the overlap layer is passive, and a combined structure of the passivation portion and the overlap layer is also passive.
In this embodiment, a first thickness of the first passive structure 9012 is smaller than a thickness of the first electrode layer 9004, a second thickness of the second passive structure 9013 is smaller than a thickness of the second electrode layer 9006, and the first thickness is equal to or approximately equal to the second thickness.
In this embodiment, a first width of the first raised portion matches an acoustic wavelength of a primary lateral acoustic mode generated by the resonant region 9100, e.g., a rayleigh S1 mode, or a TE1 mode (e.g., the first width is equal to an integer multiple of one-half wavelength), a second width of the second raised portion matches an acoustic wavelength of a primary lateral acoustic mode generated by the resonant region 9100 (e.g., the second width is equal to an integer multiple of one-half wavelength), and the first width is equal to or approximately equal to the second width. It should be noted that the first raised portion and the second raised portion are used for matching acoustic impedances of the resonance region and the attenuation region, so that more sound waves generated by the resonance region propagate into the attenuation region.
In this embodiment, the first sub-layer a is located on one side of the first raised portion in the vertical direction, and the second sub-layer b is located on one side of the first raised portion in the horizontal direction. In this embodiment, the third sub-layer c is located on one side of the second raised portion in the vertical direction, and the fourth sub-layer d is located on one side of the second raised portion in the horizontal direction. The thickness of the raised portion is matched with the thickness of the sub-layers (e.g., the second sub-layer b and the fourth sub-layer d) of the electrode layer on the horizontal direction side, that is, the thickness of the raised portion is close to the thickness of the sub-layers, so that the continuity of the sound wave propagating from the resonance region into the attenuation region can be improved, and the parasitic resonance generated in the propagation process can be reduced.
In this embodiment, a third thickness of the first extension portion is smaller than a thickness of the first electrode layer 9004, a fourth thickness of the second extension portion is smaller than a thickness of the second electrode layer 9006, and the third thickness is equal to or approximately equal to the fourth thickness.
In this embodiment, a region where the first extension portion, the second electrode extension layer 9007, and the piezoelectric layer 9001 overlap is an attenuation region 9200; a region where the second extension portion, the first electrode extension layer 9005 and the piezoelectric layer 9001 coincide is an attenuation region 9300; a second cutoff frequency of the attenuated region 9200 matches (e.g., is equal to or less than) the first cutoff frequency of the resonant region 9100, a third cutoff frequency of the attenuated region 9300 matches (e.g., is equal to or less than) the first cutoff frequency of the resonant region 9100, and the second cutoff frequency is equal to or approximately the third cutoff frequency.
It should be noted that, the cutoff frequency of the attenuation region matches the cutoff frequency of the resonance region, so that the sound wave entering the attenuation region is in an attenuation mode, that is, the wave number in the attenuation region only includes an imaginary part, and the sound wave is exponentially attenuated. Therefore, the passive structure can attenuate the transversely-propagated sound waves generated in the resonance region, inhibit parasitic edge modes and improve the parallel impedance Z p And Q value, while for Kt 2 The influence of (c) is small.
In this embodiment, the bulk acoustic wave resonator 9000 further comprises: a cavity 9014, wherein the first electrode layer 9004 is located in the cavity 9014, one end of the first electrode extension layer 9005 is located in the cavity 9014, and the first passive structure 9012 is located in the cavity 9014. In another embodiment, a lower electrode layer (e.g., the first electrode layer 9004) may be positioned over the cavity, covering the cavity; and the passive structure corresponding to the lower electrode is positioned outside the cavity.
Fig. 19 is a schematic structural diagram of a bulk acoustic wave resonator 9000 in a cross section B according to an embodiment of the present invention.
As shown in fig. 19, the bulk acoustic wave resonator 9000 includes: the piezoelectric layer 9001, the first side 9002 and the second side 9003 that the piezoelectric layer 9001 comprises; the first electrode layer 9004, located on the first side 9002, contacts the piezoelectric layer 9001, the first electrode layer 9004 comprises the first sublayer a and the second sublayer b, the first sublayer a contacts the piezoelectric layer 9001, the second sublayer b contacts the first sublayer a, the first sublayer a is located between the piezoelectric layer 9001 and the second sublayer b, the first sublayer a further comprises a ninth edge and a tenth edge opposite to the ninth edge in the horizontal direction, the ninth edge is in a downhill shape, the tenth edge is in a downhill shape, the second sublayer b comprises an eleventh edge and a twelfth edge opposite to the eleventh edge in the horizontal direction, the eleventh edge is in a downhill shape, the twelfth edge is in a downhill shape, the eleventh edge is located inside the ninth downhill edge, the twelfth edge is located inside the tenth edge, and the size of the second sublayer b is smaller than the size of the first sublayer a; the second electrode layer 9006, located on the second side 9003, contacts the piezoelectric layer 9001, the second electrode layer 9006 includes the third sublayer c and the fourth sublayer d, the third sublayer c contacts the piezoelectric layer 9001, the fourth sublayer d contacts the third sublayer c, the third sublayer c is located between the piezoelectric layer 9001 and the fourth sublayer d, the third sublayer c further includes a thirteenth edge and a fourteenth edge opposite to the thirteenth edge in the horizontal direction, the thirteenth edge is in a downslope shape, the fourteenth edge is in a downslope shape, the fourth sublayer d includes a fifteenth edge and a sixteenth edge opposite to the fifteenth edge in the horizontal direction, the fifteenth edge is in a downslope shape, the fifteenth edge is located inside the thirteenth edge, the sixteenth edge is located inside the fourteenth edge, that is, the size of the fourth sublayer d is smaller than the size of the third sublayer c; within the resonance region 9100, the ninth edge corresponds to the thirteenth edge in the vertical direction, the tenth edge corresponds to the fourteenth edge in the vertical direction, the eleventh edge corresponds to the fifteenth edge in the vertical direction, and the twelfth edge corresponds to the sixteenth edge in the vertical direction; the first passivation layer 9008 positioned at the first side 9002, the first passivation layer 9008 positioned inside the resonance region 9100 covering the first electrode layer 9004; the second passivation layer 9009 positioned at the second side 9003, the second passivation layer 9009 positioned inside the resonance region 9100 covering the second electrode layer 9006; the first overlap layer 9010 is located at the first side 9002, contacts the first passivation layer 9008, and includes the first raised portion (not labeled) and the first extension portion (not labeled), the first raised portion is raised with respect to the first extension portion, the first raised portion is located inside the resonance region 9100, and has a third overlapping portion overlapping with the ninth edge side, and has a fourth overlapping portion overlapping with the tenth edge side, the third overlapping portion extends to the eleventh edge in the horizontal direction, the fourth overlapping portion extends to the twelfth edge in the horizontal direction, the first raised portion and the first electrode layer 9004 are located at both sides of the first passivation layer 9008, the first extension portion is located outside the resonance region 9100, and is located outside the ninth edge and the tenth edge, and has no overlapping portion with the first electrode layer 9004, and the first extension portion and the piezoelectric layer 9001 include the first empty groove 9090015 therebetween; the second overlap layer 9011 is located on the second side 9003, and contacts the second passivation layer 9009, the second overlap layer 9011 includes the second raised portion (not labeled) and the second extending portion (not labeled), the second raised portion is raised with respect to the second extending portion, the second raised portion is located inside the resonance region 9100, the second raised portion further includes a fifth overlapping portion overlapping with the thirteenth edge side, and a sixth overlapping portion overlapping with the fourteenth edge side, the fifth overlapping portion extends to the fifteenth edge in the horizontal direction, the sixth overlapping portion extends to the sixteenth edge in the horizontal direction, the second raised portion and the second electrode layer 9006 are located on both sides of the second passivation layer 9009, the second extending portion is located outside the resonance region 9100, the second raised portion is located outside the thirteenth edge and the fourteenth edge, and the sixth electrode layer 9006 has no overlapping portion, and the second empty groove 9016 is included between the second extending portion and the piezoelectric layer 9001.
In this embodiment, an overlapped region of the first extending portion, the second extending portion and the piezoelectric layer 9001 is an attenuation region 9400; a fourth cutoff frequency of the attenuation region 9400 matches (e.g., is equal to or less than) the first cutoff frequency of the resonance region 9100.
Fig. 20 is a schematic structural diagram of a wireless communication apparatus 1000. As shown in fig. 20, the wireless communication apparatus 1000 includes: the radio frequency front end device 1010, the baseband processing device 1030 and the antenna 1050, wherein a first end of the radio frequency front end device 1010 is connected to the baseband processing device 1030, and a second end of the radio frequency front end device 1010 is connected to the antenna 1050. Wherein the radio frequency front end device 1010 comprises: a first filtering device 1011, a second filtering device 1013, a multiplexing device 1015, a power amplifying device 1017 and a low noise amplifying device 1019; wherein, the first filtering device 1011 is connected with the power amplifying device 1017; wherein said second filtering means 1013 is electrically connected with said low noise amplifying means 1019; the multiplexing device 1015 comprises at least one transmitting filter device (not shown) and at least one receiving filter device (not shown). Wherein, the first filtering device 1011 includes at least one bulk acoustic wave resonance device provided in one of the above-mentioned embodiments, and the second filtering device 1013 includes at least one bulk acoustic wave resonance device provided in one of the above-mentioned embodiments. Wherein the at least one transmitting filter device comprises at least one bulk acoustic wave resonator device as provided in one of the above embodiments, or the at least one receiving filter device comprises at least one bulk acoustic wave resonator device as provided in one of the above embodiments.
Fig. 21 shows one specific embodiment of the method of forming the bulk acoustic wave resonator device of the present invention, but the present invention may be practiced in other ways than those described herein, and thus the present invention is not limited to the specific embodiments disclosed below.
Fig. 21 is a flow chart illustrating a method 1100 for forming a bulk acoustic wave resonator device according to an embodiment of the present invention.
The embodiment of the invention also provides a method for forming the bulk acoustic wave resonance device, which comprises the following steps:
s1101, forming a piezoelectric layer, wherein the piezoelectric layer comprises a first side and a second side opposite to the first side in the vertical direction; forming a first electrode layer on the first side, wherein the forming of the first electrode layer comprises forming a first sublayer and a second sublayer, the first sublayer is positioned between the second sublayer and the piezoelectric layer, the first sublayer contacts the piezoelectric layer, and the first sublayer also contacts the second sublayer; forming a second electrode layer on the second side, wherein the forming of the second electrode layer includes forming a third sub-layer and a fourth sub-layer, the third sub-layer is located between the piezoelectric layer and the fourth sub-layer, the third sub-layer contacts the piezoelectric layer, the third sub-layer also contacts the fourth sub-layer, and a region where the first sub-layer, the third sub-layer and the piezoelectric layer are overlapped is a resonance region;
s1103, forming a first passive structure on the first side and contacting at least one edge of the first sub-layer, where the first passive structure includes: the first lifting part is raised relative to the first extending part; the first lifting part is positioned on the inner side of the resonance region and provided with a first superposition part with at least one edge of the first sublayer, and the first lifting part is used for matching acoustic impedances of the resonance region and at least one attenuation region on the outer side of the resonance region so that more sound waves generated in the resonance region enter the at least one attenuation region; the first passivation is located between the first raised portion and the first electrode layer, contacting at least one edge of the first sub-layer, for electrically isolating the first electrode layer from the first passive structure; the first extension part is positioned outside the resonance region and inside the at least one attenuation region and is used for attenuating the sound waves entering the at least one attenuation region;
s1105, forming a second passive structure on the second side, contacting at least one edge of the third sublayer, the second passive structure including: the second lifting part is raised relative to the second extending part; the second lifting part is positioned inside the resonance region and provided with a second overlapping part with at least one edge of the third sublayer, and the second lifting part is used for matching acoustic impedances of the resonance region and the at least one attenuation region so that more sound waves generated in the resonance region enter the at least one attenuation region; the second passivation portion is located between the second raised portion and the second electrode layer, contacting at least one edge of the third sub-layer, for electrically isolating the second electrode layer from the second passive structure; the second extension portion is located outside the resonance region and inside the at least one attenuation region, and is used for attenuating the sound waves entering the at least one attenuation region.
In some embodiments, the forming the first sub-layer comprises forming at least one first downslope edge corresponding to the first passive structure, and the forming the third sub-layer comprises forming at least one second downslope edge corresponding to the second passive structure.
In some embodiments, the second sublayer has a size smaller than the first sublayer, and the fourth sublayer has a size smaller than the third sublayer.
In some embodiments, at least one edge of the second sublayer is located inward of a corresponding at least one edge of the first sublayer, and at least one edge of the fourth sublayer is located inward of a corresponding at least one edge of the third sublayer.
In some embodiments, the first passive structure and the second passive structure surround the resonance region.
In some embodiments, the first passive structure has a thickness equal to or less than a thickness of the first electrode layer, and the second passive structure has a thickness equal to or less than a thickness of the second electrode layer.
In some embodiments, the forming the first passive structure includes forming a first passivation layer on the first side covering the first electrode layer; forming a first overlap layer contacting the first passivation layer, wherein at least one edge of the first overlap layer and at least one edge of the first sublayer have an overlap; wherein the first passivation layer includes the first passivation portion; wherein the first lap layer comprises the first raised part and the first extending part.
In some embodiments, the forming the second passive structure includes forming a second passivation layer on the second side covering the second electrode layer; forming a second overlap layer contacting the second passivation layer, wherein at least one edge of the second overlap layer and at least one edge of the third sublayer have an overlap portion; wherein the second passivation layer includes the second passivation portion; wherein the second lap layer includes the second raised portion and the second extending portion.
In some embodiments, the at least one attenuation region includes a first attenuation region having a first cutoff frequency equal to or less than a cutoff frequency of the resonance region, the first attenuation region corresponding to a region where the first extension, the piezoelectric layer, and the second extension coincide.
In some embodiments, the method of forming the bulk acoustic wave resonator device further comprises: forming a first electrode extension layer, located on the first side, connected to the first electrode layer; and forming a second electrode extension layer which is positioned on the second side and is connected with the second electrode layer.
In some embodiments, the at least one attenuation region includes a second attenuation region having a second cutoff frequency equal to or lower than a cutoff frequency of the resonance region, the second attenuation region corresponding to a region where the second electrode extension layer, the piezoelectric layer, and the first extension portion coincide with each other.
In some embodiments, the at least one attenuation region includes a third attenuation region having a third cutoff frequency equal to or less than the cutoff frequency of the resonance region, the third attenuation region corresponding to a region where the second extension, the piezoelectric layer, and the first electrode extension layer coincide.
In some embodiments, the first overlapping portion extends in a horizontal direction to at least one edge of the corresponding second sub-layer, and the second overlapping portion extends in a horizontal direction to at least one edge of the corresponding fourth sub-layer.
In some embodiments, the first sub-layer is located on one side of the first raised portion in the vertical direction, and the second sub-layer is located on one side of the first raised portion in the horizontal direction; the third sub-layer is located on one side of the second lifting part in the vertical direction, and the fourth sub-layer is located on one side of the second lifting part in the horizontal direction.
In some embodiments, the first extension portion has a thickness less than a thickness of the first electrode layer, and the second extension portion has a thickness less than a thickness of the second electrode layer.
In some embodiments, the width of the first raised portion is an integer multiple of one-half wavelength of the acoustic wave generated within the resonance region, and the width of the second raised portion is an integer multiple of one-half wavelength of the acoustic wave generated within the resonance region.
In some embodiments, the forming a first bead layer comprises; and forming a first overlap sub-layer and a second overlap sub-layer, wherein the second overlap sub-layer and the piezoelectric layer are positioned at two sides of the first overlap sub-layer, and the material of the first overlap sub-layer is different from that of the second overlap sub-layer.
In some embodiments, said forming a second bead layer comprises; and forming a third lapping sub-layer and a fourth lapping sub-layer, wherein the fourth lapping sub-layer and the piezoelectric layer are positioned at two sides of the third lapping sub-layer, and the material of the third lapping sub-layer is different from that of the fourth lapping sub-layer.
In some embodiments, the method of forming a bulk acoustic wave resonator device further comprises: forming a first sacrificial layer between the first extension and the piezoelectric layer; forming a second sacrificial layer between the second extension and the piezoelectric layer.
In some embodiments, the method of forming the bulk acoustic wave resonator device further comprises: removing the first sacrificial layer to form a first empty groove located between the first extending portion and the piezoelectric layer; and removing the second sacrificial layer to form a second empty groove which is positioned between the second extending part and the piezoelectric layer.
In some embodiments, the first passivation is also located between the piezoelectric layer and the first extension, and the second passivation is also located between the piezoelectric layer and the second extension.
In some embodiments, further comprising: forming a third passivation portion located on the second side and in contact with the second electrode layer; and forming a surrounding type groove, located in the third passivation part, located inside the resonance region, located inside the second raised part, and adjacent to the second raised part.
In some embodiments, the shape of the encircling groove comprises: circular, elliptical, or polygonal.
It should be noted that the raised portion of the passive structure is located inside the resonance region, and has a superposition portion with the electrode layer, so that acoustic impedances of the resonance region and the attenuation region outside the resonance region can be matched, and thus more acoustic waves generated by the resonance region propagate into the attenuation region. In addition, the thickness of the raised part is matched with the thickness of the sub-layer of the electrode layer on the horizontal direction side, namely the thickness of the raised part is close to the thickness of the sub-layer, so that the continuity of sound waves which are transmitted from the resonance region into the attenuation region can be improved, and the parasitic resonance generated in the transmission process can be reduced. In addition, the cutoff frequency of the attenuation region matches (e.g., is equal to or less than) the cutoff frequency of the resonance region, which can attenuate sound waves entering the attenuation region, suppress parasitic edge modes, and raise Z p And corresponding Q value, while for Kt 2 The influence of (c) is small. Wherein, the cut-off frequency is the frequency corresponding to the wave number of 0 on the dispersion curve.
Fig. 22 to 25 show one specific embodiment of the method of forming the bulk acoustic wave resonator device of the present invention, but the present invention may be implemented in other ways than those described herein, and thus the present invention is not limited to the specific embodiment disclosed below.
Fig. 22 to 25 are schematic structural diagrams of a cross section a of a method for forming a bulk acoustic wave resonator 1200 according to an embodiment of the present invention.
As shown in fig. 22, the method of forming the bulk acoustic wave resonator device 1200 includes: forming a piezoelectric layer 1201, the piezoelectric layer 1201 including a first side 1202 and a second side 1203 vertically opposing the first side 1202; forming a first electrode layer 1204 on the first side 1202 in contact with the piezoelectric layer 1201, the forming the first electrode layer 1204 including forming a first sub-layer a and a second sub-layer b, the first sub-layer a contacting the piezoelectric layer 1201, the second sub-layer b contacting the first sub-layer a, the first sub-layer a being between the piezoelectric layer 1201 and the second sub-layer b, the first sub-layer a including a first edge and a second edge opposite to the first edge in a horizontal direction, the second sub-layer b including a third edge and a fourth edge opposite to the third edge in the horizontal direction, the third edge being inside the first edge, the fourth edge being aligned with the second edge, the size of the second sub-layer b being smaller than the size of the first sub-layer a; a first electrode extension layer 1205 is formed, located at the first side 1202, contacting the piezoelectric layer 1201, the first electrode extension layer 1205 being connected to the second edge and the fourth edge of the first electrode layer 1204.
In this embodiment, the method for forming the bulk acoustic wave resonator 1200 further includes: a first substrate (not shown) is provided prior to the formation of the piezoelectric layer 1201. In this embodiment, the piezoelectric layer 1201 is formed on one side of the first substrate, and the first substrate is located on the second side 1203.
In this embodiment, the forming the first electrode layer 1204 includes: forming a first, downwardly sloping edge at said first edge; forming a second downhill edge located at said third edge.
As shown in fig. 23, the method of forming the bulk acoustic wave resonator device 1200 further includes: forming a first passivation layer 1206 on the first side 1202, the first passivation layer 1206 covering the first electrode layer 1204, the first passivation layer 1206 further covering the piezoelectric layer 1201 outside the first edge, the first passivation layer 1206 further covering the first electrode extension layer 1205 outside the second edge and the fourth edge; forming a first lap layer 1207 on the first side 1202 to contact the first passivation layer 1206, where the first lap layer 1207 includes a first raised portion (not labeled) and a first extending portion (not labeled), the first raised portion is raised relative to the first extending portion, the first raised portion is located inside the first edge and has a first overlapping portion overlapping with the first edge, the first overlapping portion extends to the third edge along the horizontal direction, the first raised portion and the first electrode layer 1204 are located on two sides of the first passivation layer 1206, the first extending portion is located outside the first edge and has no overlapping portion with the first electrode layer 1204, and the first extending portion and the piezoelectric layer 1201 are located on two sides of the first passivation layer 1206.
In this embodiment, the method for forming the bulk acoustic wave resonator 1200 further includes: forming a sacrificial layer 1208 on the first side 1202, covering the first electrode layer 1204, an end of the first electrode extension layer 1205 connected to the second edge and the fourth edge, and the first lap layer 1207, wherein the first passivation layer 1206 is included between the sacrificial layer 1208 and the first electrode layer 1204 and the first electrode extension layer 1205.
In this embodiment, the method for forming the bulk acoustic wave resonator 1200 further includes: a first connection layer (not shown) is formed on the first side 1202 covering the sacrificial layer 1208 and the first passivation layer 1206.
In another embodiment, the method of forming a bulk acoustic wave resonator device further includes: forming a sacrificial layer having an overlapping portion with a lower electrode layer (for example, the first electrode layer 1204), wherein a passivation layer is included between the sacrificial layer and the lower electrode layer, a lower lap layer corresponding to the lower electrode layer is located on a first side of the sacrificial layer in the horizontal direction, and a lower electrode extension layer is located on a second side of the sacrificial layer in the horizontal direction; and forming a connecting layer to cover the sacrificial layer, the lower lapping layer and the passivation layer.
In this embodiment, the method for forming the bulk acoustic wave resonator 1200 further includes: providing a second substrate (not shown); forming a second connection layer (not shown) on one side of the second substrate to cover the second substrate; bonding the first and second connection layers to form an intermediate layer (not shown), the second substrate and the intermediate layer being located on the first side 1202; and removing the first substrate. In this embodiment, bonding the first connection layer and the second connection layer includes: bonding the first and second connection layers or adhering the first and second connection layers.
As shown in fig. 24, the method for forming the bulk acoustic wave resonator device 1200 further includes: forming a second electrode layer 1209 on the second side 1203 and in contact with the piezoelectric layer 1201, wherein the forming of the second electrode layer 1209 includes forming a third sublayer c and a fourth sublayer d, the third sublayer c is in contact with the piezoelectric layer 1201, the fourth sublayer d is in contact with the third sublayer c, the third sublayer c is between the piezoelectric layer 1201 and the fourth sublayer d, the third sublayer c includes a fifth edge and a sixth edge opposite to the fifth edge in the horizontal direction, the fourth sublayer d includes a seventh edge and an eighth edge opposite to the seventh edge in the horizontal direction, the eighth edge is located inside the sixth edge, the fifth edge is aligned with the seventh edge, and the size of the fourth sublayer d is smaller than that of the third sublayer c; forming a second electrode extension layer 1210 on the second side 1203, the second electrode extension layer 1210 contacting the piezoelectric layer 1201, the second electrode extension layer 1210 being connected to a fifth edge and a seventh edge of the second electrode layer 1209, wherein the fifth edge and the seventh edge vertically correspond to the first edge, and the sixth edge vertically corresponds to the second edge and the fourth edge.
In this embodiment, the forming the second electrode layer 1209 includes: forming a third downhill edge located at said sixth edge; forming a fourth downhill edge, located at said eighth edge.
As shown in fig. 25, the method for forming the bulk acoustic wave resonator device 1200 further includes: forming a second passivation layer 1211 located on the second side 1203, wherein the second passivation layer 1211 covers the second electrode layer 1209, the second passivation layer 1211 further covers the piezoelectric layer 1201 outside the sixth edge, and the second passivation layer 1211 further covers the second electrode extension layer 1210 outside the fifth edge and the seventh edge; forming a second overlap edge layer 1212 at the second side 1203 and contacting the second passivation layer 1211, wherein the second overlap edge layer 1212 includes a second raised portion (not labeled) and a second extending portion (not labeled), the second raised portion is raised relative to the second extending portion, the second raised portion is located inside the sixth edge and has a second overlapping portion overlapping with the sixth edge, the second overlapping portion extends to the eighth edge along the horizontal direction, the second raised portion and the second electrode layer 1209 are located on two sides of the second passivation layer 1211, the second extending portion is located outside the sixth edge and has no overlapping portion with the second electrode layer 1209, and the second extending portion and the piezoelectric layer 1201 are located on two sides of the second passivation layer 1211.
In this embodiment, the method for forming the bulk acoustic wave resonator 1200 further includes: the sacrificial layer 1208 is removed to form a cavity 1213, and the first electrode layer 1204, an end of the first electrode extension layer 1205 connected to the second edge and the fourth edge, and the first lap layer 1207 are located in the cavity 1213.
In this embodiment, the first overlap layer 1207 and a first passivation (not labeled) on the first passivation layer 1206 that coincides with the first overlap layer 1207 form a first passive structure 1214 on the first side 1202 contacting the first edge of the first sublayer a, the third edge of the second sublayer b, and the piezoelectric layer 1201 outside the first edge; a second passivation (not labeled) on the second overlap layer 1212 and the second passivation 1211, which coincides with the second overlap layer 1212, forms a second passive structure 1215 located on the second side 1203, contacting the sixth edge of the third sublayer c, the eighth edge of the fourth sublayer d, and the piezoelectric layer 1201 outside the sixth edge. The passivation portion includes a dielectric material, and the electrode layer and the edge bead layer are electrically isolated from each other and are not electrically connected to each other, so that the edge bead layer is passive, and a combined structure of the passivation portion and the edge bead layer is also passive.
In this embodiment, a first thickness of the first passive structure 1214 is less than a thickness of the first electrode layer 1204, a second thickness of the second passive structure 1215 is less than a thickness of the second electrode layer 1209, and the first thickness is equal to or approximately equal to the second thickness.
In this embodiment, a region where the first sub-layer a, the third sub-layer c and the piezoelectric layer 1201 overlap is a resonance region 1220, and a region where the first extension portion, the second electrode extension layer 1210 and the piezoelectric layer 1201 overlap is an attenuation region 1230; the area where the second extension, the first electrode extension layer 1205 and the piezoelectric layer 1201 coincide is an attenuation region 1240; a second cutoff frequency of the attenuation region 1230 matches (e.g., is equal to or less than) the first cutoff frequency of the resonance region 1220, a third cutoff frequency of the attenuation region 1240 matches (e.g., is equal to or less than) the first cutoff frequency of the resonance region 1220, and the second cutoff frequency is equal to or approximately the third cutoff frequency.
In this embodiment, a first width of the first raised portion matches an acoustic wavelength of a primary transverse acoustic mode generated by the resonance region (e.g., the first width equals an integer multiple of one-half wavelength), such as a rayleigh lamb S1 mode or a TE1 mode, and a second width of the second raised portion matches an acoustic wavelength of a primary transverse acoustic mode generated by the resonance region (e.g., the second width equals an integer multiple of one-half wavelength), the first width being equal to or approximately equal to the second width. The first raised portion and the second raised portion are used to match acoustic impedances of the resonance region and the attenuation region, so that more of the sound waves generated by the resonance region propagate into the attenuation region.
In this embodiment, the first sub-layer a is located on one side of the first raised portion in the vertical direction, and the second sub-layer b is located on one side of the first raised portion in the horizontal direction. In this embodiment, the third sub-layer c is located on one side of the second raised portion in the vertical direction, and the fourth sub-layer d is located on one side of the second raised portion in the horizontal direction. The thickness of the raised portion is matched with the thickness of the sub-layers (e.g., the second sub-layer b and the fourth sub-layer d) of the electrode layer on the horizontal direction side, that is, the thickness of the raised portion is close to the thickness of the sub-layers, so that the continuity of the sound wave propagating from the resonance region into the attenuation region can be improved, and the parasitic resonance generated in the propagation process can be reduced.
In this embodiment, a third thickness of the first extension portion is smaller than a thickness of the first electrode layer 1204, a fourth thickness of the second extension portion is smaller than a thickness of the second electrode layer 1209, and the third thickness is equal to or approximately equal to the fourth thickness.
It should be noted that the cutoff frequency of the attenuation region is matched with the cutoff frequency of the resonance region, so that the sound wave entering the attenuation region is in an attenuation mode, that is, the wave number in the attenuation region only includes an imaginary part, and the sound wave is exponentially attenuated, so that the transversely propagated sound wave generated in the resonance region can be attenuated, a parasitic edge mode is suppressed, and the parallel impedance Z is improved p And Q value, while for Kt 2 Has a smaller influence.
In another embodiment, forming the bead layer includes: forming a first overlap sub-layer contacting the passivation layer; and forming a second overlap sub-layer to contact the first overlap sub-layer, wherein the passivation layer and the second overlap sub-layer are located on two sides of the first overlap sub-layer, the material of the first overlap sub-layer is different from that of the second overlap sub-layer, for example, the material of the first overlap sub-layer is molybdenum, and the material of the second overlap sub-layer is platinum or tungsten.
Fig. 26 shows one embodiment of a method of forming the bulk acoustic wave resonator device of the present invention, but the present invention can be implemented in other ways than those described herein, and thus the present invention is not limited to the embodiments disclosed below.
In the present embodiment, the description of the bulk acoustic wave resonator device is continued on the basis of the method for forming the bulk acoustic wave resonator device 1200 in the above-described embodiment, and the difference between the present embodiment and the above-described embodiment is that: the bulk acoustic wave resonator device 1200 further includes a third passivation and a surrounding groove. The following detailed description will be made in conjunction with the accompanying drawings.
As shown in fig. 26, in addition to fig. 25, fig. 26 is described, and the method for forming the bulk acoustic wave resonator device 1200 further includes: forming a third passivation portion (not labeled) on the second side 1203 and in contact with the second electrode layer 1209; a wrap-around groove 1216 in the third passivation, inside the resonance region 1220, inside the second raised portion, and adjacent to the second raised portion.
In this embodiment, the surrounding groove 1216 has a polygonal shape. In other embodiments, the circumferential groove may also be circular or elliptical.
The second passivation layer 1211 includes the third passivation portion and the second passivation portion.
In this embodiment, the surrounding groove 1216, the first section I formed by the surrounding groove 1216, and the second section II formed by the first raised portion and the second raised portion are added inside the resonance region 1220. By setting the cutoff frequency of the first section region I to be higher than the cutoff frequency of the intermediate portion (not labeled) of the resonance region 1220 inside the surrounding-type groove 1216 and setting the cutoff frequency of the second section region II to be lower than the cutoff frequency of the intermediate portion, a piston mode (piston mode) is formed, see fig. 26, which shows a sound velocity distribution diagram in a piston mode where the sound velocity is proportional to the cutoff frequency, and the piston mode is excited to suppress higher-order spurious modes of transverse sound waves, as shown in fig. 33, and the series resonance frequency (f) is reduced s ) Near and less than f s Clutter of the portion (c).
Fig. 27 and 28 show one embodiment of a method of forming a bulk acoustic wave resonator device of the present invention, but the present invention may be practiced in other ways than those described herein, and thus the present invention is not limited to the embodiments disclosed below.
In the present embodiment, the description of the bulk acoustic wave resonator device is continued on the basis of the method for forming the bulk acoustic wave resonator device 1200 in the above-described embodiment, and the difference between the present embodiment and the above-described embodiment is that: the bulk acoustic wave resonator device 1200 further includes a third passivation and a surrounding groove. The following detailed description will be made in conjunction with the accompanying drawings.
As shown in fig. 27, the method for forming the bulk acoustic wave resonator device 11200 further includes, in addition to fig. 23, the steps of fig. 27: forming a third passivation portion (not labeled) on the first side 1202 and contacting the first electrode layer 1204; a wrap-around groove 1216 in the third passivation, inside the resonance region 1220, inside the first raised portion, and adjacent to the first raised portion.
In this embodiment, the circumferential groove 1116 has a polygonal shape. In other embodiments, the circumferential groove may also be circular or oval.
Note that the first passivation layer 1206 includes the third passivation portion and the first passivation portion.
It should be noted that, after the surrounding type groove is formed, the subsequent processes are consistent with fig. 25 and the corresponding description until the bulk acoustic wave resonator device 1200 (as shown in fig. 28) is formed.
In this embodiment, the surrounding groove 1216, the first section I formed by the surrounding groove 1216, and the second section II formed by the first raised portion and the second raised portion are added inside the resonance region 1220. By setting the cut-off frequency of the first section region I to be higher than the cut-off frequency of the middle portion (not labeled) of the resonance region 1220 inside the surrounding groove 1216 and setting the cut-off frequency of the second section region II to be lower than the cut-off frequency of the middle portion, a piston mode (piston mode) is formed, see fig. 28, showing a sound velocity profile in the piston mode, where the sound velocity is proportional to the cut-off frequency, and the excitation of the piston mode can suppress transverse sound wavesAs shown in fig. 33, reduces the series resonance frequency (f) s ) Near and less than f s Of the portion (c).
Fig. 29 to 32 show one specific embodiment of the method of forming the bulk acoustic wave resonator device of the present invention, but the present invention may be implemented in other ways than those described herein, and thus the present invention is not limited to the specific embodiment disclosed below.
Fig. 29 to 32 are schematic cross-sectional a structural diagrams illustrating a method for forming a bulk acoustic wave resonator 1300 according to an embodiment of the present invention.
As shown in fig. 29, the method of forming the bulk acoustic wave resonator device 1300 includes: forming a piezoelectric layer 1301, wherein the piezoelectric layer 1301 comprises a first side 1302 and a second side 1303 opposite to the first side 1302 in the vertical direction; forming a first electrode layer 1304 on the first side 1302 in contact with the piezoelectric layer 1301, wherein the forming the first electrode layer 1304 includes forming a first sub-layer a and a second sub-layer b, wherein the first sub-layer a is in contact with the piezoelectric layer 1301, the second sub-layer b is in contact with the first sub-layer a, the first sub-layer a is located between the piezoelectric layer 1301 and the second sub-layer b, the first sub-layer a includes a first edge and a second edge opposite to the first edge in a horizontal direction, the second sub-layer b includes a third edge and a fourth edge opposite to the third edge in the horizontal direction, the third edge is located inside the first edge, the fourth edge is aligned with the second edge, and the size of the second sub-layer b is smaller than that of the first sub-layer a; a first electrode extension layer 1305 is formed on the first side 1302 contacting the piezoelectric layer 1301, the first electrode extension layer 1305 is connected to the second edge and the fourth edge of the first electrode layer 1304.
In this embodiment, the method for forming the bulk acoustic wave resonator 1300 further includes: before the piezoelectric layer 1301 is formed, a first substrate (not shown) is provided. In this embodiment, the piezoelectric layer 1301 is formed on one side of the first substrate, and the first substrate is located on the second side 1303.
In this embodiment, the forming the first electrode layer 1304 includes: forming a first, downwardly sloping edge at said first edge; forming a second downhill edge located at said third edge.
As shown in fig. 30, the method for forming the bulk acoustic wave resonator device 1300 further includes: forming a first passivation layer 1306 on the first side 1302, the first passivation layer 1306 covering the first electrode layer 1304 and also covering the first electrode extension layer 1305 outside the second edge and the fourth edge; forming a sacrificial layer 1307 on the first side 1302, outside the first edge, contacting the piezoelectric layer 1301 and the first passivation layer 1306; forming a first overlap layer 1308 on the first side 1302, contacting the first passivation layer 1306 and the sacrificial layer 1307, where the first overlap layer 1308 includes a first raised portion (not labeled) and a first extending portion (not labeled), where the first raised portion is raised with respect to the first extending portion, the first raised portion is located inside the first edge, and has a first overlapping portion overlapping with the first edge, the first overlapping portion extends to the third edge along the horizontal direction, the first raised portion and the first electrode layer 1304 are located on two sides of the first passivation layer 1306, the first extending portion is located outside the first edge, and has no overlapping portion with the first electrode layer 1304, and the first extending portion and the piezoelectric layer 1301 are located on two sides of the sacrificial layer 1307.
In this embodiment, the method for forming the bulk acoustic wave resonator 1300 further includes: forming a sacrificial layer 1309 on the first side 1302, covering the first electrode layer 1304, an end of the first electrode extension layer 1305 connected to the second edge and the fourth edge, the first edge lapping layer 1308, and the sacrificial layer 1307, wherein the first passivation layer 1306 is included between the sacrificial layer 1309 and the first electrode layer 1304 and the first electrode extension layer 1305.
In this embodiment, the method for forming the bulk acoustic wave resonator 1300 further includes: a first connection layer (not shown) is formed on the first side 1302, covering the sacrificial layer 1309 and the first passivation layer 1306.
In this embodiment, the method for forming the bulk acoustic wave resonator 1300 further includes: providing a second substrate (not shown); forming a second connection layer (not shown) on one side of the second substrate to cover the second substrate; bonding the first and second tie layers to form an intermediate layer (not shown), the second substrate and the intermediate layer being located on the first side 1302; and removing the first substrate. In this embodiment, bonding the first connection layer and the second connection layer includes: bonding the first and second connection layers or adhering the first and second connection layers.
As shown in fig. 31, the method for forming the bulk acoustic wave resonator device 1300 further includes: forming a second electrode layer 1310, located on the second side 1303, in contact with the piezoelectric layer 1301, wherein the forming of the second electrode layer 1310 includes forming a third sublayer c and a fourth sublayer d, the third sublayer c is in contact with the piezoelectric layer 1301, the fourth sublayer d is in contact with the third sublayer c, the third sublayer c is located between the piezoelectric layer 1301 and the fourth sublayer d, the third sublayer c includes a fifth edge and a sixth edge opposite to the fifth edge in the horizontal direction, the fourth sublayer d includes a seventh edge and an eighth edge opposite to the seventh edge in the horizontal direction, the eighth edge is located inside the sixth edge, the fifth edge is aligned with the seventh edge, and the size of the fourth sublayer d is smaller than that of the third sublayer c; forming a second electrode extension layer 1311 on the second side 1303 and contacting the piezoelectric layer 1301, wherein the second electrode extension layer 1311 is connected to a fifth edge and a seventh edge of the second electrode layer 1310, the fifth edge and the seventh edge vertically correspond to the first edge, and the sixth edge vertically corresponds to the second edge and the fourth edge.
In this embodiment, the forming the second electrode layer 1310 includes: forming a third downhill edge located at said sixth edge; forming a fourth downhill edge, located at said eighth edge.
As shown in fig. 32, the method for forming the bulk acoustic wave resonator device 1300 further includes: forming a second passivation layer 1312 on the second side 1303, wherein the second passivation layer 1312 covers the second electrode layer 1310 and also covers the second electrode extension layer 1311 outside the fifth edge and the seventh edge; forming a dummy sacrificial layer (not shown), for example, the sacrificial layer 1307, on the second side 1303, outside the sixth edge, contacting the piezoelectric layer 1301 and the second passivation layer 1312; forming a second overlap layer 1313 on the second side 1303, where the second overlap layer 1313 is located on the second side 1303 and contacts the second passivation layer 1312 and the empty slot sacrificial layer, where the second overlap layer 1313 includes a second raised portion (not labeled) and a second extending portion (not labeled), the second raised portion is raised relative to the second extending portion, the second raised portion is located inside the sixth edge and has a second overlapping portion overlapping with the sixth edge, the second overlapping portion extends to the eighth edge along the horizontal direction, the second raised portion and the second electrode layer 1310 are located on two sides of the second passivation layer 1312, the second extending portion is located outside the sixth edge and has no overlapping with the second electrode layer 1310, and the second extending portion and the piezoelectric layer 1301 are located on two sides of the empty slot sacrificial layer.
In this embodiment, the method for forming the bulk acoustic wave resonator 1300 further includes: the sacrificial layer 1309 is removed to form a cavity 1314, and the first electrode layer 1304, an end of the first electrode extension layer 1305 connected to the second edge and the fourth edge, and the first lap layer 1308 are located in the cavity 1314.
In this embodiment, the method for forming the bulk acoustic wave resonator 1300 further includes: the sacrificial layer 1307 and the empty groove sacrificial layer are removed to form an empty groove 1315 and an empty groove 1316 respectively.
In this embodiment, the first overlap layer 1308, the first passivation portion (not labeled) on the first passivation layer 1306 coinciding with the first overlap layer 1308, and the empty trench 1315 form a first passive structure 1317 on the first side 1302, contacting the first edge of the first sub-layer a and the third edge of the second sub-layer b; the second ledge layer 1313, a second passivation (not labeled) on the second passivation layer 1312 coinciding with the second ledge layer 1313, and the empty slot 1316 form a second passive structure 1318 on the second side 1303, contacting the sixth edge of the third sublayer c and the eighth edge of the fourth sublayer d. The passivation portion includes a dielectric material, and the electrode layer and the overlap layer are electrically isolated from each other and are not electrically connected to each other, so that the overlap layer is passive, and a combined structure of the passivation portion and the overlap layer is also passive.
In this embodiment, the first passive structure 1317 has a first thickness that is less than the thickness of the first electrode layer 1304, the second passive structure 1318 has a second thickness that is less than the thickness of the second electrode layer 1310, and the first thickness is equal to or approximately equal to the second thickness.
In this embodiment, the overlapped area of the first sublayer a, the third sublayer c and the piezoelectric layer 1301 is a resonance area 1320, and the overlapped area of the first extension portion, the second electrode extension layer 1311 and the piezoelectric layer 1301 is an attenuation area 1330; the area where the second extension portion, the first electrode extension layer 1305 and the piezoelectric layer 1301 are overlapped is an attenuation region 1340; a second cutoff frequency of the attenuation region 1330 matches (e.g., is equal to or less than) the first cutoff frequency of the resonance region 1320, a third cutoff frequency of the attenuation region 1340 matches (e.g., is equal to or less than) the first cutoff frequency of the resonance region 1320, and the second cutoff frequency is equal to or approximately the third cutoff frequency.
In this embodiment, a first width of the first raised portion matches an acoustic wavelength of a fundamental mode of transverse acoustic waves generated by the resonance region 1320 (e.g., a rayleigh S1 mode, or a TE1 mode) (e.g., the first width is equal to an integer multiple of one-half wavelength), a second width of the second raised portion matches an acoustic wavelength of a fundamental mode of transverse acoustic waves generated by the resonance region 1320 (e.g., the second width is equal to an integer multiple of one-half wavelength), and the first width is equal to or approximately equal to the second width. It should be noted that the first raised portion and the second raised portion are used for matching acoustic impedances of the resonance region and the attenuation region, so that more sound waves generated by the resonance region propagate into the attenuation region.
In this embodiment, the first sub-layer a is located on one side of the first raised portion in the vertical direction, and the second sub-layer b is located on one side of the first raised portion in the horizontal direction. In this embodiment, the third sub-layer c is located on one side of the second raised portion in the vertical direction, and the fourth sub-layer d is located on one side of the second raised portion in the horizontal direction. It should be noted that the thickness of the raised portion matches the thickness of the sub-layer of the electrode layer on the horizontal side, that is, the thickness of the raised portion is close to the thickness of the sub-layer, so that the continuity of the sound wave propagating from the resonance region into the attenuation region can be improved, and the parasitic resonance generated in the propagation process can be reduced.
In this embodiment, a third thickness of the first extension portion is smaller than the thickness of the first electrode layer 1304, a fourth thickness of the second extension portion is smaller than the thickness of the second electrode layer 1310, and the third thickness is equal to or approximately equal to the fourth thickness.
It should be noted that the cutoff frequency of the attenuation region is matched with the cutoff frequency of the resonance region, so that the sound wave entering the attenuation region is in an attenuation mode, that is, the wave number in the attenuation region only includes an imaginary part, and the sound wave is exponentially attenuated, so that the transversely-propagated sound wave generated in the resonance region can be attenuated, the parasitic edge mode is suppressed, and the Z-axis direction is improved p And corresponding Q value, while for Kt 2 Has a smaller influence.
In another embodiment, forming the bead layer includes: forming a first overlap sub-layer contacting the passivation layer; and forming a second overlap sub-layer to contact the first overlap sub-layer, wherein the passivation layer and the second overlap sub-layer are located on two sides of the first overlap sub-layer, the material of the first overlap sub-layer is different from that of the second overlap sub-layer, for example, the material of the first overlap sub-layer is molybdenum, and the material of the second overlap sub-layer is platinum or tungsten.
To sum up, the passive structure includes a raised portion located inside the resonance region and having an overlap with the electrode layer, and can match acoustic impedances of the resonance region and the attenuation region outside the resonance region, so that more sound waves generated by the resonance region propagate into the attenuation region. Furthermore, the thickness of the raised part is adaptedThe thickness of the sub-layer of the electrode layer on the horizontal direction side, namely the thickness of the lifting part is close to the thickness of the sub-layer, so that the continuity of sound waves which are transmitted from the resonance region into the attenuation region can be improved, and parasitic resonance generated in the transmission process is reduced. In addition, the cutoff frequency of the attenuation region matches (e.g., is equal to or less than) the cutoff frequency of the resonance region, which can attenuate sound waves entering the attenuation region, suppress parasitic edge modes, and raise Z p And corresponding Q value, while for Kt 2 Has a smaller influence.
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 (55)
1. A bulk acoustic wave resonator device, comprising:
a cavity;
a first electrode layer, at least one end of the first electrode layer being located above or within the cavity, the first electrode layer comprising a first sub-layer and a second sub-layer, the first sub-layer contacting the second sub-layer;
the piezoelectric layer comprises a first side and a second side opposite to the first side in the vertical direction, the cavity is located on the first side, the first electrode layer is located on the first side, the first sub-layer is also in contact with the piezoelectric layer, and the first sub-layer is located between the second sub-layer and the piezoelectric layer;
the second electrode layer is positioned on the second side and comprises a third sublayer and a fourth sublayer, the third sublayer is in contact with the piezoelectric layer and also in contact with the fourth sublayer, the third sublayer is positioned between the piezoelectric layer and the fourth sublayer, and the superposed area of the first sublayer, the third sublayer and the piezoelectric layer is a resonance area;
a first passive structure on the first side in contact with at least one edge of the first sublayer;
a second passive structure on the second side in contact with at least one edge of the third sublayer;
wherein the first passive structure comprises:
a first raised part which is positioned inside the resonance region and has a first overlapping part with at least one edge of the first sublayer, wherein the first raised part is used for matching acoustic impedances of the resonance region and at least one attenuation region outside the resonance region, so that more sound waves generated in the resonance region enter the at least one attenuation region;
a first passivation portion located between the first raised portion and the first electrode layer for electrically isolating the first electrode layer from the first passive structure;
a first extension located outside the resonance region and within the at least one attenuation region for attenuating sound waves entering the at least one attenuation region, the first raised portion being raised relative to the first extension;
the second passive structure includes:
a second raised part which is positioned inside the resonance region and has a second overlapping part with at least one edge of the third sublayer, wherein the second raised part is used for matching acoustic impedances of the resonance region and the at least one attenuation region so that more sound waves generated in the resonance region enter the at least one attenuation region;
a second passivation portion located between the second raised portion and the second electrode layer for electrically isolating the second electrode layer from the second passive structure;
and the second extension part is positioned outside the resonance region and in the at least one attenuation region and is used for attenuating the sound waves entering the at least one attenuation region, and the second lifting part is raised relative to the second extension part.
2. The bulk acoustic wave resonator device according to claim 1, wherein at least one edge of the first sublayer is downslope shaped, corresponding to the first passive structure; at least one edge of the third sublayer is in a downhill shape corresponding to the second passive structure.
3. The bulk acoustic wave resonator device of claim 1, wherein the size of the second sublayer is smaller than the size of the first sublayer, and the size of the fourth sublayer is smaller than the size of the third sublayer.
4. The bulk acoustic wave resonator device of claim 1, wherein at least one edge of the second sublayer is located inward of a corresponding at least one edge of the first sublayer and at least one edge of the fourth sublayer is located inward of a corresponding at least one edge of the third sublayer.
5. The bulk acoustic wave resonator device of claim 4, wherein the at least one edge of the first sublayer comprises a first edge and the at least one edge of the second sublayer comprises a second edge, the first edge vertically corresponding to the second edge, the second edge being located inward of the first edge.
6. The bulk acoustic wave resonator device of claim 4, wherein the at least one edge of the third sublayer comprises a third edge and the at least one edge of the fourth sublayer comprises a fourth edge, the third edge vertically corresponding to the fourth edge, the fourth edge being located inward of the third edge.
7. The bulk acoustic wave resonator device of claim 1, wherein the first passive structure and the second passive structure surround the resonance region.
8. The bulk acoustic wave resonator device according to claim 1, wherein a thickness of the first passive structure is equal to or less than a thickness of the first electrode layer, and a thickness of the second passive structure is equal to or less than a thickness of the second electrode layer.
9. The bulk acoustic wave resonator device according to claim 1, wherein the at least one attenuation region includes a first attenuation region having a first cutoff frequency equal to or lower than a cutoff frequency of the resonance region, the first attenuation region corresponding to a region where the first extension portion, the piezoelectric layer, and the second extension portion coincide.
10. The bulk acoustic wave resonator device of claim 1, further comprising: a first electrode extension layer located at the first side and connected with the first electrode layer; and the second electrode extension layer is positioned on the second side and is connected with the second electrode layer.
11. The bulk acoustic wave resonator device according to claim 10, wherein the at least one attenuation region includes a second attenuation region having a second cutoff frequency equal to or lower than a cutoff frequency of the resonance region, the second attenuation region corresponding to a region where the second electrode extension layer, the piezoelectric layer, and the first extension portion coincide with each other.
12. The bulk acoustic wave resonator device according to claim 10, wherein the at least one attenuation region includes a third attenuation region having a third cutoff frequency equal to or lower than a cutoff frequency of the resonance region, the third attenuation region corresponding to a region where the second extension portion, the piezoelectric layer, and the first electrode extension layer coincide.
13. The bulk acoustic wave resonator device according to claim 1, wherein the width of the first raised portion is an integral multiple of one-half wavelength of the acoustic wave generated in the resonance region, and the width of the second raised portion is an integral multiple of one-half wavelength of the acoustic wave generated in the resonance region.
14. The bulk acoustic wave resonator device according to claim 1, wherein the material of the first raised portion comprises a metal, the material of the first extension portion comprises a metal, the material of the second raised portion comprises a metal, and the material of the second extension portion comprises a metal.
15. The bulk acoustic wave resonator device according to claim 1, wherein the first sub-layer is located on one side of the first raised portion in the vertical direction, and the second sub-layer is located on one side of the first raised portion in the horizontal direction; the third sub-layer is located on one side of the second lifting portion in the vertical direction, and the fourth sub-layer is located on one side of the second lifting portion in the horizontal direction.
16. The bulk acoustic wave resonator device according to claim 1, wherein the first overlap portion extends in a horizontal direction to at least one edge of the corresponding second sublayer, and the second overlap portion extends in a horizontal direction to at least one edge of the corresponding fourth sublayer.
17. The bulk acoustic wave resonator device according to claim 1, wherein a thickness of the first extension portion is smaller than a thickness of the first electrode layer, and a thickness of the second extension portion is smaller than a thickness of the second electrode layer.
18. The bulk acoustic wave resonator device according to claim 1, wherein the first extension portion includes a first sub-portion and a second sub-portion, the second sub-portion and the piezoelectric layer are located on both sides of the first sub-portion, and a material of the first sub-portion is different from a material of the second sub-portion.
19. The bulk acoustic wave resonator device according to claim 1, wherein the second extension portion includes a third sub-portion and a fourth sub-portion, the piezoelectric layer and the fourth sub-portion are located on both sides of the third sub-portion, and a material of the third sub-portion is different from a material of the fourth sub-portion.
20. The bulk acoustic wave resonator device of claim 1, wherein the material of the first passivation comprises a dielectric and the material of the second passivation comprises a dielectric.
21. The bulk acoustic wave resonator device of claim 1, wherein the first passivation is further located between the piezoelectric layer and the first extension, and the second passivation is further located between the piezoelectric layer and the second extension.
22. The bulk acoustic wave resonator device of claim 1, wherein a first void is included between the first extension and the piezoelectric layer, and a second void is included between the piezoelectric layer and the second extension.
23. The bulk acoustic wave resonator device of claim 1, further comprising: a third passivation portion located on the second side and contacting the second electrode layer; and the surrounding groove is positioned in the third passivation part, positioned on the inner side of the resonance area, positioned on the inner side of the second raised part and adjacent to the second raised part.
24. The bulk acoustic wave resonator device according to claim 23, wherein the shape of the circumferential groove comprises: circular, elliptical, or polygonal.
25. The bulk acoustic wave resonator device of claim 1, further comprising: a third passivation portion located on the first side and contacting the first electrode layer; and the surrounding type groove is positioned in the third passivation part, is positioned on the inner side of the resonance area, is positioned on the inner side of the first raised part and is adjacent to the first raised part.
26. The bulk acoustic wave resonator device of claim 25, wherein the shape of the surround-type groove comprises: circular, elliptical, or polygonal.
27. A filtering apparatus, comprising: at least one bulk acoustic wave resonator device as claimed in any one of claims 1 to 26.
28. A radio frequency front end device, comprising: power amplifying means and at least one filtering means according to claim 27; the power amplifying device is connected with the filtering device.
29. A radio frequency front end apparatus, comprising: low noise amplifying means and at least one filtering means according to claim 27; the low-noise amplifying device is connected with the filtering device.
30. A radio frequency front end apparatus, comprising: multiplexing device comprising at least one filtering device according to claim 27.
31. A method of forming a bulk acoustic wave resonator device, comprising:
forming a piezoelectric layer including a first side and a second side opposite the first side in a vertical direction;
forming a first electrode layer on the first side, wherein the forming of the first electrode layer comprises forming a first sublayer and a second sublayer, the first sublayer is positioned between the second sublayer and the piezoelectric layer, the first sublayer contacts the piezoelectric layer, and the first sublayer also contacts the second sublayer;
forming a second electrode layer on the second side, wherein the forming of the second electrode layer includes forming a third sub-layer and a fourth sub-layer, the third sub-layer is located between the piezoelectric layer and the fourth sub-layer, the third sub-layer contacts the piezoelectric layer, the third sub-layer also contacts the fourth sub-layer, and a region where the first sub-layer, the third sub-layer and the piezoelectric layer are overlapped is a resonance region;
forming a first passive structure on the first side in contact with at least one edge of the first sublayer;
wherein the first passive structure comprises:
the first lifting part is raised relative to the first extending part; the first lifting part is positioned on the inner side of the resonance region and provided with a first superposition part with at least one edge of the first sublayer, and the first lifting part is used for matching acoustic impedances of the resonance region and at least one attenuation region on the outer side of the resonance region so that more sound waves generated in the resonance region enter the at least one attenuation region; the first passivation is located between the first raised portion and the first electrode layer, contacting at least one edge of the first sub-layer, for electrically isolating the first electrode layer from the first passive structure; the first extension part is positioned outside the resonance region and inside the at least one attenuation region and is used for attenuating the sound waves entering the at least one attenuation region;
forming a second passive structure on the second side in contact with at least one edge of the third sublayer,
wherein the second passive structure comprises:
the second lifting part is raised relative to the second extending part; the second lifting part is positioned inside the resonance region and provided with a second overlapping part with at least one edge of the third sublayer, and the second lifting part is used for matching acoustic impedances of the resonance region and the at least one attenuation region so that more sound waves generated in the resonance region enter the at least one attenuation region; the second passivation portion is located between the second raised portion and the second electrode layer, contacting at least one edge of the third sub-layer, for electrically isolating the second electrode layer from the second passive structure; the second extension is located outside the resonance region, within the at least one attenuation region, and is configured to attenuate sound waves entering the at least one attenuation region.
32. The method of forming a bulk acoustic wave resonator device according to claim 31, wherein forming the first sublayer comprises forming at least one first downslope edge corresponding to the first passive structure, and wherein forming the third sublayer comprises forming at least one second downslope edge corresponding to the second passive structure.
33. The method of forming a bulk acoustic wave resonator device according to claim 31, wherein the size of the second sublayer is smaller than the size of the first sublayer, and the size of the fourth sublayer is smaller than the size of the third sublayer.
34. The method of forming a bulk acoustic wave resonator device according to claim 31, wherein at least one edge of the second sub-layer is located inward of a corresponding at least one edge of the first sub-layer, and wherein at least one edge of the fourth sub-layer is located inward of a corresponding at least one edge of the third sub-layer.
35. The method of forming a bulk acoustic wave resonator device, according to claim 31, wherein the first passive structure and the second passive structure surround the resonance region.
36. The method of forming a bulk acoustic wave resonator device according to claim 31, wherein the first passive structure has a thickness equal to or less than a thickness of the first electrode layer, and the second passive structure has a thickness equal to or less than a thickness of the second electrode layer.
37. The method of forming a bulk acoustic wave resonator device according to claim 31, wherein the forming the first passive structure comprises forming a first passivation layer on the first side covering the first electrode layer; forming a first overlap layer contacting the first passivation layer, wherein at least one edge of the first overlap layer and at least one edge of the first sublayer have an overlap; wherein the first passivation layer includes the first passivation portion; wherein the first lap layer comprises the first raised part and the first extending part.
38. The method of forming a bulk acoustic wave resonator device according to claim 31, wherein said forming a second passive structure comprises forming a second passivation layer on said second side overlying said second electrode layer; forming a second overlap layer contacting the second passivation layer, wherein at least one edge of the second overlap layer and at least one edge of the third sublayer have an overlap portion; wherein the second passivation layer includes the second passivation portion; wherein the second lap layer includes the second raised portion and the second extending portion.
39. The method of forming a bulk acoustic wave resonator device according to claim 31, wherein the at least one attenuation region includes a first attenuation region having a first cutoff frequency equal to or lower than a cutoff frequency of the resonance region, the first attenuation region corresponding to a region where the first extension, the piezoelectric layer, and the second extension overlap.
40. The method of forming a bulk acoustic wave resonator device according to claim 31, further comprising:
forming a first electrode extension layer, located on the first side, connected to the first electrode layer; and forming a second electrode extension layer which is positioned on the second side and is connected with the second electrode layer.
41. The method of forming a bulk acoustic wave resonator device according to claim 40, wherein the at least one attenuation region includes a second attenuation region having a second cutoff frequency equal to or lower than a cutoff frequency of the resonance region, the second attenuation region corresponding to a region where the second electrode extension layer, the piezoelectric layer, and the first extension portion coincide.
42. The method of forming a bulk acoustic wave resonator device according to claim 40, wherein the at least one attenuation region includes a third attenuation region having a third cutoff frequency equal to or lower than a cutoff frequency of the resonance region, the third attenuation region corresponding to a region where the second extension portion, the piezoelectric layer, and the first electrode extension layer coincide.
43. The method of forming a bulk acoustic wave resonator device according to claim 31, wherein the first overlap extends horizontally to a corresponding at least one edge of the second sublayer, and the second overlap extends horizontally to a corresponding at least one edge of the fourth sublayer.
44. The method of forming a bulk acoustic wave resonator device according to claim 31, wherein the first sublayer is located on one side of the first raised portion in the vertical direction, and the second sublayer is located on one side of the first raised portion in the horizontal direction; the third sub-layer is located on one side of the second lifting part in the vertical direction, and the fourth sub-layer is located on one side of the second lifting part in the horizontal direction.
45. The method of forming a bulk acoustic wave resonator device according to claim 31, wherein a thickness of the first extension portion is smaller than a thickness of the first electrode layer, and a thickness of the second extension portion is smaller than a thickness of the second electrode layer.
46. The method of forming a bulk acoustic wave resonator device according to claim 31, wherein the width of the first raised portion is an integral multiple of one-half wavelength of the acoustic wave generated in the resonance region, and the width of the second raised portion is an integral multiple of one-half wavelength of the acoustic wave generated in the resonance region.
47. The method of forming a bulk acoustic wave resonator device according to claim 37, wherein the forming the first overlap layer comprises; forming a first butt-strap sublayer and a second butt-strap sublayer, wherein the second butt-strap sublayer and the piezoelectric layer are positioned on two sides of the first butt-strap sublayer, and the material of the first butt-strap sublayer is different from that of the second butt-strap sublayer.
48. The method of forming a bulk acoustic wave resonator device according to claim 38, wherein said forming a second overlap layer comprises; and forming a third overlap sub-layer and a fourth overlap sub-layer, wherein the fourth overlap sub-layer and the piezoelectric layer are positioned at two sides of the third overlap sub-layer, and the material of the third overlap sub-layer is different from that of the fourth overlap sub-layer.
49. The method of forming a bulk acoustic wave resonator device according to claim 31, further comprising: forming a first sacrificial layer between the first extension and the piezoelectric layer; forming a second sacrificial layer between the second extension and the piezoelectric layer.
50. The method of forming a bulk acoustic wave resonator device of claim 49, further comprising: removing the first sacrificial layer to form a first empty groove which is positioned between the first extension part and the piezoelectric layer; and removing the second sacrificial layer to form a second empty groove which is positioned between the second extending part and the piezoelectric layer.
51. The method of forming a bulk acoustic wave resonator device according to claim 31, wherein the first passivation is further located between the piezoelectric layer and the first extension, and the second passivation is further located between the piezoelectric layer and the second extension.
52. The method of forming a bulk acoustic wave resonator device according to claim 31, further comprising: forming a third passivation portion located on the second side and in contact with the second electrode layer; and forming a surrounding groove, which is positioned in the third passivation part, is positioned inside the resonance area, is positioned inside the second raised part, and is adjacent to the second raised part.
53. The method of forming a bulk acoustic wave resonator device according to claim 52, wherein the shape of the circumferential groove comprises: circular, elliptical, or polygonal.
54. The method of forming a bulk acoustic wave resonator device according to claim 31, further comprising: forming a third passivation portion located on the first side and in contact with the first electrode layer; and forming a surrounding type groove, wherein the surrounding type groove is positioned in the third passivation part, positioned on the inner side of the resonance area, positioned on the inner side of the first lifting part and adjacent to the first lifting part.
55. The method of forming a bulk acoustic wave resonator device according to claim 54, wherein the shape of the surround type groove comprises: circular, elliptical, or polygonal.
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| CN202210778139.3A CN115189670A (en) | 2022-06-28 | 2022-06-28 | Bulk acoustic wave resonator device, forming method thereof, filter device and radio frequency front end device |
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