CN111786654B - Bulk acoustic wave resonator, method of manufacturing the same, filter, and radio frequency communication system - Google Patents
Bulk acoustic wave resonator, method of manufacturing the same, filter, and radio frequency communication system Download PDFInfo
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Images
Classifications
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- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
- H03H9/00—Networks comprising electromechanical or electro-acoustic devices; Electromechanical resonators
- H03H9/15—Constructional features of resonators consisting of piezoelectric or electrostrictive material
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- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
- H03H3/00—Apparatus or processes specially adapted for the manufacture of impedance networks, resonating circuits, resonators
- H03H3/007—Apparatus or processes specially adapted for the manufacture of impedance networks, resonating circuits, resonators for the manufacture of electromechanical resonators or networks
- H03H3/02—Apparatus or processes specially adapted for the manufacture of impedance networks, resonating circuits, resonators for the manufacture of electromechanical resonators or networks for the manufacture of piezoelectric or electrostrictive resonators or networks
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
- H03H9/00—Networks comprising electromechanical or electro-acoustic devices; Electromechanical resonators
- H03H9/15—Constructional features of resonators consisting of piezoelectric or electrostrictive material
- H03H9/17—Constructional features of resonators consisting of piezoelectric or electrostrictive material having a single resonator
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
- H03H9/00—Networks comprising electromechanical or electro-acoustic devices; Electromechanical resonators
- H03H9/15—Constructional features of resonators consisting of piezoelectric or electrostrictive material
- H03H9/17—Constructional features of resonators consisting of piezoelectric or electrostrictive material having a single resonator
- H03H9/171—Constructional features of resonators consisting of piezoelectric or electrostrictive material having a single resonator implemented with thin-film techniques, i.e. of the film bulk acoustic resonator [FBAR] type
- H03H9/172—Means for mounting on a substrate, i.e. means constituting the material interface confining the waves to a volume
- H03H9/174—Membranes
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- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
- H03H9/00—Networks comprising electromechanical or electro-acoustic devices; Electromechanical resonators
- H03H9/46—Filters
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
- H03H9/00—Networks comprising electromechanical or electro-acoustic devices; Electromechanical resonators
- H03H9/46—Filters
- H03H9/462—Microelectro-mechanical filters
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
- H03H9/00—Networks comprising electromechanical or electro-acoustic devices; Electromechanical resonators
- H03H9/46—Filters
- H03H9/54—Filters comprising resonators of piezo-electric or electrostrictive material
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- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
- H03H9/00—Networks comprising electromechanical or electro-acoustic devices; Electromechanical resonators
- H03H9/46—Filters
- H03H9/54—Filters comprising resonators of piezo-electric or electrostrictive material
- H03H9/547—Notch filters, e.g. notch BAW or thin film resonator filters
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- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
- H03H9/00—Networks comprising electromechanical or electro-acoustic devices; Electromechanical resonators
- H03H9/15—Constructional features of resonators consisting of piezoelectric or electrostrictive material
- H03H2009/155—Constructional features of resonators consisting of piezoelectric or electrostrictive material using MEMS techniques
Abstract
The invention provides a bulk acoustic wave resonator, a manufacturing method thereof, a filter and a radio frequency communication system, wherein a bottom electrode convex part and a top electrode concave part which are formed at the periphery of a piezoelectric resonance layer and suspended above a cavity can prevent transverse waves generated by the piezoelectric resonance layer from being transmitted to the periphery of the cavity and reflect the transverse waves back to an effective working area, so that the acoustic wave loss is reduced, the quality factor of the resonator is improved, and the performance of a device can be finally improved. Further, the overlapping parts of the bottom electrode overlapping part and the top electrode overlapping part and the cavity are all suspended, and the bottom electrode overlapping part and the top electrode overlapping part are staggered mutually, so that parasitic parameters can be greatly reduced, the problems of electric leakage, short circuit and the like are avoided, and the reliability of the device can be improved.
Description
Technical Field
The invention relates to the technical field of radio frequency communication, in particular to a bulk acoustic wave resonator, a manufacturing method thereof, a filter and a radio frequency communication system.
Background
Radio Frequency (RF) communications, such as those used in mobile phones, require the use of RF filters, each capable of passing a desired frequency and limiting all other frequencies. With the development of mobile communication technology, the amount of mobile data transmission is also rapidly increasing. Therefore, increasing the transmission power of a wireless power transmitting device such as a wireless base station, a micro base station or a repeater becomes a problem that must be considered under the premise that the frequency resources are limited and the mobile communication device should be used as little as possible, and the requirement for the filter power in the front-end circuit of the mobile communication device is higher and higher.
At present, a high-power filter in a wireless base station and other devices is mainly a cavity filter, and the power of the high-power filter can reach hundreds of watts, but the size of the high-power filter is too large. There are also devices that use dielectric filters with average powers of up to 5 watts or more, which are also large in size. Due to the large size, these two filters cannot be integrated into the rf front-end chip.
With the more mature MEMS technology, the filter composed of Bulk Acoustic Wave (BAW) resonators can overcome the above two kinds of filter defects. The bulk acoustic wave resonator has the advantages of incomparable volume of a ceramic dielectric filter and incomparable working frequency and power capacity of a Surface Acoustic Wave (SAW) resonator, and becomes the development trend of the current wireless communication system.
The bulk acoustic wave resonator has a sandwich structure formed by a bottom electrode, a piezoelectric film and a top electrode, converts electric energy into mechanical energy by utilizing the inverse piezoelectric effect of the piezoelectric film, and forms standing waves in a filter formed by the bulk acoustic wave resonator in the form of acoustic waves. Since the speed of an acoustic wave is 5 orders of magnitude smaller than that of an electromagnetic wave, the size of a filter constituted by a bulk acoustic wave resonator is smaller than that of a conventional dielectric filter or the like.
The working principle of the cavity type bulk acoustic wave resonator is that the acoustic waves are reflected at the interface of a bottom electrode or a supporting layer and air, the acoustic waves are limited on a piezoelectric layer, resonance is achieved, and the cavity type bulk acoustic wave resonator has the advantages of being high in Q value, low in insertion loss, capable of being integrated and the like, and is widely adopted.
However, the quality factor (Q) of the currently manufactured cavity bulk acoustic wave resonator cannot be further improved, and thus the requirement of a high-performance radio frequency system cannot be met.
Disclosure of Invention
The invention aims to provide a bulk acoustic wave resonator, a manufacturing method thereof, a filter and a radio frequency communication system, which can improve the quality factor and further improve the device performance.
In order to achieve the above object, the present invention provides a bulk acoustic wave resonator comprising:
a substrate;
the bottom electrode layer is arranged on the substrate, a cavity is formed between the bottom electrode layer and the substrate, the bottom electrode layer is provided with a bottom electrode protruding part, and the bottom electrode protruding part is positioned in the area of the cavity and protrudes towards the direction far away from the bottom surface of the cavity;
a piezoelectric resonance layer formed on the bottom electrode layer above the cavity;
the top electrode layer is formed on the piezoelectric resonance layer, the top electrode layer has a top electrode depressed part, the top electrode depressed part is located in the region of cavity and towards being close to the direction of the bottom surface of cavity is sunken, the top electrode depressed part with the bottom electrode bellying all is located in the outlying cavity region of piezoelectric resonance layer, the bottom electrode bellying with the top electrode depressed part all centers on the peripheral direction extension of piezoelectric resonance layer, and the two is at least partially relative.
The invention also provides a filter comprising at least one bulk acoustic wave resonator according to the invention.
The invention also provides a radio frequency communication system comprising at least one filter according to the invention.
The present invention also provides a method for manufacturing a bulk acoustic wave resonator, comprising:
providing a substrate, and forming a first sacrificial layer with a sacrificial bulge on a part of the substrate;
forming a bottom electrode layer on the first sacrificial layer, wherein the bottom electrode layer covers the part on the surface of the sacrificial protrusion to form a bottom electrode protrusion part;
forming a piezoelectric resonance layer on the bottom electrode layer, wherein the piezoelectric resonance layer exposes the bottom electrode bulge;
forming a second sacrificial layer with a first groove in an exposed area around the piezoelectric resonance layer;
forming a top electrode layer on the piezoelectric resonance layer and a part of the second sacrificial layer around the piezoelectric resonance layer, wherein the part of the top electrode layer covering the first groove forms a top electrode recess;
and removing the second sacrificial layer and the first sacrificial layer with the sacrificial protrusions, wherein cavities are formed at the positions of the second sacrificial layer and the first sacrificial layer with the sacrificial protrusions, the top electrode concave part and the bottom electrode convex part are located in the cavity region on the periphery of the piezoelectric resonance layer, and the bottom electrode convex part and the top electrode concave part extend around the peripheral direction of the piezoelectric resonance layer and are at least partially opposite to each other.
Compared with the prior art, the technical scheme of the invention has the following beneficial effects:
1. when electric energy is applied to the bottom electrode and the top electrode, a desired longitudinal wave propagating along the thickness direction and an undesired transverse wave propagating along the plane of the piezoelectric resonance layer are generated through a piezoelectric phenomenon generated in the piezoelectric resonance layer, the transverse wave can be blocked at the bottom electrode protruding part and the top electrode recessed part which are suspended on the cavity on the periphery of the piezoelectric resonance layer and reflected back to the corresponding region of the piezoelectric resonance layer, and then the loss caused when the transverse wave propagates to the film layer on the periphery of the cavity is reduced and reduced, so that the acoustic wave loss is improved, the quality factor of the resonator is improved, and finally the device performance can be improved.
2. The periphery on piezoelectricity resonance layer and the peripheral alternate segregation of cavity, piezoelectricity resonance layer can not extend to the peripheral substrate top of cavity continuously promptly, can restrict the effective working area of bulk acoustic wave syntonizer in the cavity region completely, and bottom electrode overlap joint portion and top electrode overlap joint portion all can extend to the part edge of cavity (bottom electrode layer and top electrode layer do not all can not cover the cavity comprehensively promptly), can reduce the influence of the longitudinal vibration that the rete produced piezoelectricity resonance layer around the cavity from this, the high performance.
3. Even if the bottom electrode convex part and the top electrode concave part have the mutually overlapped parts, the overlapped parts are also in a gap structure, so that the parasitic parameters can be greatly reduced, the problems of electric contact and the like of the top electrode layer and the bottom electrode layer in a cavity region are avoided, and the reliability of the device can be improved.
4. Bottom electrode overlap joint portion and top electrode overlap joint portion and the overlap portion of cavity all are unsettled, and bottom electrode overlap joint portion and top electrode overlap joint portion stagger each other in the region of cavity (the two does not overlap in the cavity region promptly), can greatly reduced parasitic parameter from this to avoid bottom electrode overlap joint portion and top electrode overlap joint portion to contact and the electric leakage that arouses, short circuit scheduling problem, can improve the device reliability.
5. The bottom electrode overlapping part completely covers the cavity above the cavity part where the bottom electrode overlapping part is located, so that the membrane layer above the bottom electrode overlapping part with a large area can be strongly and mechanically supported, and the problem of failure of a device due to cavity collapse is avoided.
6. The top electrode depressed part surrounds a top electrode resonance portion for a circle, and the bottom electrode bellying surrounds a bottom electrode resonance portion for a circle, can follow the peripheral omnidirectional of piezoelectricity resonance layer and block the transverse wave, and then obtain the quality factor of preferred.
7. Bottom electrode bellying, bottom electrode resonance portion and bottom electrode overlap joint portion adopt same rete to form, and the membrane is thick even, top electrode bellying, top electrode resonance portion and top electrode overlap joint portion adopt same rete to form, and the membrane is thick even, can simplify the technology from this, and the cost is reduced, and because the membrane of bottom electrode bellying is thick basically the same with other parts of bottom electrode layer, the membrane of top electrode bellying is thick basically the same with other parts of top electrode layer, consequently bottom electrode bellying fracture and the cracked condition of top electrode bellying can not appear, can improve the reliability of device.
Drawings
Fig. 1A is a schematic top view of a bulk acoustic wave resonator according to an embodiment of the present invention.
Fig. 1B and 1C are schematic sectional views along the lines XX 'and YY' in fig. 1.
Fig. 2A to 2D are schematic top-view structural diagrams of bulk acoustic wave resonators according to other embodiments of the present invention.
Fig. 2E and 2F are schematic cross-sectional structures of bulk acoustic wave resonators according to other embodiments of the present invention.
Fig. 3 is a flowchart of a method for manufacturing a bulk acoustic wave resonator according to an embodiment of the present invention.
Fig. 4A to 4H are schematic cross-sectional views along XX' in fig. 1A in a method of manufacturing a bulk acoustic wave resonator according to an embodiment of the present invention.
Fig. 5 is a schematic sectional view taken along XX' in fig. 1A in a method of manufacturing a bulk acoustic wave resonator according to another embodiment of the present invention.
Wherein the reference numbers are as follows:
100-a substrate; 101, etching a protective layer; 102-a cavity; 102' -a second groove; 102A-active working area; 102B-null area; 103-a first sacrificial layer; 1033' -sacrificial bumps; 104-bottom electrode layer (i.e. remaining bottom electrode material layer); 1040-bottom electrode lap; 1041-bottom electrode projection; 1042-bottom electrode resonance part; 1043-a bottom electrode periphery; 105-a layer of piezoelectric material; 1050-a piezoelectric peripheral portion; 1051-a piezoelectric resonance layer (or called as a piezoelectric resonance part); 106-a second sacrificial layer; 107-sacrificial bumps; 108-the top electrode layer (i.e., the remaining layer of top electrode material); 1080-top electrode lap; 1081-top electrode recess; 1082-a top electrode resonance part; 1083-top electrode peripheral portion.
Detailed Description
The technical solution of the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments. The advantages and features of the present invention will become more apparent from the following description. It is to be noted that the drawings are in a very simplified form and are not to precise scale, which is merely for the purpose of facilitating and distinctly claiming the embodiments of the present invention. Similarly, if the method described herein comprises a series of steps, the order in which these steps are presented herein is not necessarily the only order in which these steps may be performed, and some of the described steps may be omitted and/or some other steps not described herein may be added to the method. In addition, something "offset from" something in this context means that the two do not overlap in the region of the cavity, i.e. that the projections of the two onto the bottom surface of the cavity do not overlap.
Referring to fig. 1A to 1C, fig. 1A is a schematic top view of a bulk acoustic wave resonator according to an embodiment of the present invention, fig. 1B is a schematic cross-sectional structure along XX 'in fig. 1, fig. 1C is a schematic cross-sectional structure along YY' in fig. 1A, and the bulk acoustic wave resonator of the present embodiment includes: a substrate, a bottom electrode layer 104, a piezoelectric resonance layer 1051, and a top electrode layer 108.
The substrate comprises a base 100 and an etching protection layer 101 covering the base 100. The substrate 100 may be any suitable substrate known to those skilled in the art, and may be, for example, at least one of the following materials: silicon (Si), germanium (Ge), silicon germanium (SiGe), silicon carbon (SiC), silicon germanium carbon (SiGeC), indium arsenide (InAs), gallium arsenide (GaAs), indium phosphide (InP), or other III/V compound semiconductors, and further includes a multilayer structure composed of these semiconductors, or may be Silicon On Insulator (SOI), silicon on insulator (SSOI), silicon germanium on insulator (S-SiGeOI), silicon germanium on insulator (SiGeOI), and germanium on insulator (GeOI), or may be Double-Side Polished silicon Wafers (DSP), or may be a ceramic substrate such as alumina, quartz, or a glass substrate. The material of the etching protection layer 101 may be any suitable dielectric material, including but not limited to at least one of silicon oxide, silicon nitride, silicon oxynitride, silicon carbonitride, and the like, and the etching protection layer may be used to increase structural stability of the finally manufactured bulk acoustic wave resonator, increase isolation between the bulk acoustic wave resonator and the substrate 100, and reduce a requirement on resistivity of the substrate 100, and on the other hand, protect other regions of the substrate from being etched in the process of manufacturing the bulk acoustic wave resonator, thereby improving device performance and reliability.
A cavity 102 is formed between the bottom electrode layer 104 and the substrate. Referring to fig. 1A to 1C, in the present embodiment, the cavity 102 may be formed by sequentially etching the etching protection layer 101 and the substrate 100 with a partial thickness through an etching process, so as to form a groove structure with a whole bottom recessed in the substrate. However, the technology of the present invention is not limited thereto, and referring to fig. 2E, in another embodiment of the present invention, the cavity 102 may also be formed above the top surface of the etching protection layer 101 by a process of removing a sacrificial layer protruding from the surface of the etching protection layer 101 by a post-removal method, so as to form a cavity structure protruding from the surface of the etching protection layer 101. In addition, in the embodiment, the bottom surface of the cavity 102 is rectangular, but in other embodiments of the invention, the bottom surface of the cavity 102 may also be circular, oval, or polygonal other than rectangular, such as pentagonal, hexagonal, etc.
The piezoelectric resonance layer 1051, which may be referred to as a piezoelectric resonance portion, is located in an upper region of the cavity 102 (or in a region of the cavity 102), corresponding to an effective operating region of the bulk acoustic wave resonator, and the piezoelectric resonance layer 1051 is provided between the bottom electrode layer 104 and the top electrode layer 108. The bottom electrode layer 104 includes a bottom electrode lap 1040, a bottom electrode protrusion 1041, and a bottom electrode resonance portion 1042, which are sequentially connected, the top electrode layer 108 includes a top electrode lap 1080, a top electrode recess 1081, and a top electrode resonance portion 1082, which are sequentially connected, the bottom electrode resonance portion 1042 and the top electrode resonance portion 1082 are both overlapped with the piezoelectric resonance layer 1051, and the cavity 102 and the areas corresponding to the bottom electrode resonance portion 1042, the piezoelectric resonance layer 1051, and the top electrode resonance portion 1082, which are overlapped together, form an effective working area 102A of the bulk acoustic wave resonator, the portion of the cavity 102 other than the effective working area 102A is an inactive area 102B, the piezoelectric resonance layer 1051 is located in the effective working area 102A and separated from the film layers around the cavity 102, the effective working area of the bulk acoustic wave resonator can be completely limited in the area of the cavity 102, the influence of the film layers around the cavity on the longitudinal vibration generated by the piezoelectric resonance layer can be reduced, the parasitic parameters generated in the inactive area 102B can be reduced, and the device performance can be improved. The bottom electrode resonance portion 1042, the piezoelectric resonance layer 1051, and the top electrode resonance portion 1082 are flat structures whose upper and lower surfaces are planar, the bottom electrode protrusion 1041 is located above the cavity 102B at the periphery of the active working area 102A and electrically connected to the bottom electrode resonance portion 1042, and protrudes toward a direction away from the bottom surface of the cavity, and the top electrode recess 1081 is located above the cavity 102B at the periphery of the active working area 102A and electrically connected to the top electrode resonance portion 1082, and protrudes toward a direction away from the bottom surface of the cavity 102. The bottom electrode raised portion 1041 is higher than the top surface of the bottom electrode resonance portion 1042 as a whole, the top electrode recessed portion 1081 is lower than the top surface of the top electrode resonance portion 1082 as a whole, and both the top electrode recessed portion 1081 and the bottom electrode raised portion 1041 are located in a cavity region (i.e., 102B) in the periphery of the piezoelectric resonance layer 1051. The bottom electrode protrusion 1041 and the top electrode recess 1081 may be solid structures, or may be hollow structures, preferably hollow structures, so that the film thicknesses of the bottom electrode layer 104 and the top electrode layer 108 are uniform, the bottom electrode resonance portion 1042 and the piezoelectric resonance layer 1051 are prevented from being separated by gravity of the solid bottom electrode protrusion 1041, and the top electrode resonance portion 1082 and the piezoelectric resonance layer 1051 and the bottom electrode resonance portion 1042 below the top electrode resonance portion 1081 are prevented from being deformed by the solid top electrode recess 1081, thereby further improving the resonance factor. The bottom electrode resonance part 1042 and the top electrode resonance part 1082 are polygonal (both the top surface and the bottom surface are polygonal), and the shapes of the bottom electrode resonance part 1042 and the top electrode resonance part 1082 may be similar (as shown in fig. 2A to 2B and 2D) or identical (as shown in fig. 1A and 2C). The piezoelectric resonance layer 1051 has a polygonal structure similar to the shapes of the bottom electrode resonance portion 1042 and the top electrode resonance portion 1082.
Referring to fig. 1A to 1C, in the present embodiment, the bottom electrode layer 104, the piezoelectric resonance layer 1051 and the top electrode layer 108 form a film structure in a shape of a "watch", one corner of the bottom electrode overlap 1040 and the bottom electrode overlap 1042 is aligned, one corner of the top electrode overlap 10840 and the top electrode resonance portion 1082 is aligned, the bottom electrode overlap 1040 and the top electrode overlap 10840 correspond to two watchbands of the "watch", the bottom electrode protrusion 1041 is disposed along an edge of the bottom electrode resonance portion 1042 and is only disposed in an area where the bottom electrode overlap 1040 and the bottom electrode resonance portion 1042 are aligned, the top electrode recess 1081 is disposed along an edge of the top electrode resonance portion 1082 and is only disposed in an area where the top electrode overlap 1080 and the top electrode resonance portion 1082 are aligned, the bottom electrode protrusion 1041 and the top electrode recess 1081 correspond to a connection structure between a dial of the "watch" and two watchbands ", the effective area 102A cavity portion, the bottom electrode protrusion 1081 and the bottom electrode layer are separated from the surrounding substrate of the watch band by the film structure, and the bottom electrode layer is separated from the watch band by the surrounding substrate and the bottom electrode substrate. That is, in this embodiment, the bottom electrode protrusion 1041 and the top electrode recess 1081 both extend around the peripheral direction of the piezoelectric resonance layer 1051, and the bottom electrode protrusion 1041 and the top electrode recess 1081 only surround part of the edge of the piezoelectric resonance layer 1051 along the peripheral direction of the piezoelectric resonance layer 1051, respectively, and with the plane where the piezoelectric resonance layer 1051 is located as a reference, the top electrode recess 1081 and the bottom electrode protrusion 1041 are respectively located at two sides of the piezoelectric resonance layer 1051 and are completely opposite to each other, so that while a certain transverse wave blocking effect is achieved, the reduction of the areas of the inactive area 102B not covered by the top electrode overlapping portion 1080 and the bottom electrode overlapping portion 1040 can be facilitated, and thus the reduction of the size of the device is facilitated, and the reduction of the areas of the top electrode overlapping portion 1080 and the bottom electrode overlapping portion 1040 is facilitated, so as to further reduce parasitic parameters, and improve the electrical performance of the device. The bottom electrode bonding portion 1040 is electrically connected to a side of the bottom electrode protruding portion 1041 facing away from the bottom electrode resonance portion 1042, and extends from the bottom electrode protruding portion 1041 to a portion of the etching protection layer 101 on the periphery of the cavity 102 after suspending above the cavity (i.e., 102B) outside the bottom electrode protruding portion 1041; the top electrode bonding portion 1080 is electrically connected to one side of the top electrode recess 1081, which faces away from the top electrode resonance portion 1082, and extends from the top electrode recess 1081 to a position above a part of the etching protection layer 101 on the periphery of the cavity 102 after being suspended above the cavity (i.e., 102B) outside the top electrode recess 1081; the bottom electrode overlapping portion 1040 and the top electrode overlapping portion 1080 extend to the upper side of the substrate outside two opposite sides of the cavity 102, and at this time, the bottom electrode overlapping portion 1040 and the top electrode overlapping portion 1080 are staggered with each other (that is, the two are not overlapped) in the cavity 102 region, so that parasitic parameters can be reduced, the problems of electric leakage, short circuit and the like caused by the contact of the bottom electrode overlapping portion and the top electrode overlapping portion are avoided, and the device performance is improved. The bottom electrode lap 1040 may be configured to connect to a corresponding signal line, so as to transmit a corresponding signal to the bottom electrode resonance portion 1042 through the bottom electrode protrusion 1041, and the top electrode lap 1080 may be configured to connect to a corresponding signal line, so as to transmit a corresponding signal to the top electrode resonance portion 1082 through the top electrode recess 1081, so that the bulk acoustic wave resonator may normally operate, specifically, a time-varying voltage is applied to the bottom electrode resonance portion 1042 and the top electrode resonance portion 1082 through the bottom electrode lap 1040 and the top electrode lap 1080, so as to excite a longitudinally extending mode or a "piston" mode, the piezoelectric resonance layer 1051 converts energy in the form of electrical energy into a longitudinal wave, a parasitic transverse wave may be generated in the process, and the bottom electrode protrusion 1041 and the top electrode recess 1081 may block the transverse wave from propagating into a film layer on the periphery of the cavity, and limit the transverse wave in the area of the cavity 102, so as to avoid energy loss caused by the transverse wave, and improve the quality factor.
Preferably, the line widths of the top electrode recess 1081 and the bottom electrode protrusion 1041 are respectively the minimum line widths allowed by the corresponding processes, and the horizontal distance between the bottom electrode protrusion 1041 and the piezoelectric resonance layer 1051 and the horizontal distance between the top electrode recess 1081 and the piezoelectric resonance layer 1051 are the minimum distances allowed by the corresponding processes, so that the top electrode recess 1081 and the bottom electrode protrusion 1041 can achieve a certain transverse wave blocking effect, and at the same time, the reduction of the device area can be facilitated.
In addition, the side wall of the top electrode recess 1081 is an inclined side wall with respect to the top surface of the piezoelectric resonance layer, as shown in fig. 1B, the cross section of the top electrode recess 1081 along the line XX' in fig. 1A is trapezoidal or trapezoid-like, and the included angles β 1 and β 2 between the two side walls of the top electrode recess 1081 and the top surface of the piezoelectric resonance layer 1051 are both less than or equal to 45 degrees, so that the top electrode recess 1081 is prevented from being broken due to the excessively vertical side wall of the top electrode recess 1081, thereby affecting the effect of transmitting signals to the top electrode resonance portion 1082, and meanwhile, the thickness uniformity of the entire top electrode layer 108 can also be improved; the side wall of bottom electrode boss 1041 is relative the bottom surface of piezoelectric resonance layer is the slope side wall, as shown in fig. 1B, bottom electrode boss 1041 is trapezoidal or trapezoidal type along the cross-section of XX ' line in fig. 1A, two side walls of bottom electrode boss 1041 with contained angle alpha 1, alpha 2 between the bottom surface of piezoelectric resonance layer 1051 all be less than or equal to 45 degrees, from this, avoid because bottom electrode layer 104 fracture because of bottom electrode boss 1041's side wall is too vertical, and then influence the effect of transmitting signal on bottom electrode resonance portion 1042, can also improve bottom electrode layer 104's thickness homogeneity simultaneously.
In a preferred embodiment of the present invention, the bottom electrode resonance portion 1042, the bottom electrode protrusion 1041 and the bottom electrode overlapping portion 1040 are formed by a same film layer manufacturing process (i.e. a same film layer manufacturing process), the top electrode resonance portion 1082, the top electrode recess 1081 and the top electrode overlapping portion 1080 are formed by a same film layer manufacturing process (i.e. a same film layer manufacturing process), i.e. the bottom electrode resonance portion 1042, the bottom electrode protrusion 1041 and the bottom electrode overlapping portion 1040 are integrally formed, and the top electrode resonance portion 1082, the top electrode recess 1081 and the top electrode overlapping portion 1080 are integrally formed, so as to simplify the process and reduce the cost, wherein, the film materials for forming the bottom electrode resonance portion 1042, the bottom electrode raised portion 1041 and the bottom electrode bonding portion 1040 and the film materials for forming the top electrode resonance portion 1082, the top electrode recessed portion 1081 and the top electrode bonding portion 1080 may be any suitable conductive materials or semiconductor materials known in the art, respectively, wherein the conductive materials may be metal materials having conductive properties, such as one or more of aluminum (Al), copper (Cu), platinum (Pt), gold (Au), molybdenum (Mo), tungsten (W), iridium (Ir), osmium (Os), rhenium (Re), palladium (Pd), rhodium (Rh) and ruthenium (Ru), and the semiconductor materials may be Si, ge, siGe, siC, siGeC, etc. In other embodiments of the present invention, the bottom electrode resonance portion 1042, the bottom electrode raised portion 1041 and the bottom electrode overlapping portion 1040 may be formed by different film layer manufacturing processes, and the top electrode resonance portion 1082, the top electrode recessed portion 1081 and the top electrode overlapping portion 1080 may be formed by different film layer manufacturing processes, under the premise of process cost and process technology.
Referring to fig. 2A to 2D, in order to further improve the transverse wave blocking effect, the bottom electrode protrusion 1041 extends to more continuous sides of the bottom electrode resonance portion 1042, the top electrode recess 1081 extends to more continuous sides of the top electrode resonance portion 1082, and when the bottom electrode protrusion 1041 and the top electrode recess 1081 are overlapped, referring to fig. 2F, a gap H is formed therebetween, so that the top electrode layer 108 and the bottom electrode layer 104 are not electrically contacted, and the short circuit problem is avoided. For example, referring to fig. 2A, the projections of the bottom electrode protrusion 1041 and the top electrode recess 1081 on the bottom surface of the cavity 102 may be exactly connected or nearly connected, that is, the projections of the bottom electrode protrusion 1041 and the top electrode recess 1081 on the bottom surface of the cavity 102 may form a completely closed ring or a nearly closed ring, so that the matching of the bottom electrode protrusion 1041 and the top electrode recess 1081 may block the transverse wave of the entire periphery of the piezoelectric resonant layer 1051, in this case, the projection sizes of the bottom electrode protrusion 1041 and the top electrode recess 1081 on the bottom surface of the cavity 102 may be equally divided (at this time, the bottom electrode protrusion 1041 and the top electrode recess 1081 are located on two sides of the piezoelectric resonant layer 1051 and all portions are completely opposite), or not equally divided (at this time, the bottom electrode protrusion 1041 and the top electrode recess 1081 are located on two sides of the piezoelectric resonant layer 1051 and only portions are opposite to each other). For another example, referring to fig. 2B, the piezoelectric resonance layer 1051, the top electrode resonance portion 1082 and the bottom electrode resonance portion 1042 are all pentagonal planar structures, the area of the piezoelectric resonance layer 1051 is the smallest, the area of the top electrode resonance portion 1082 is the second, and the area of the bottom electrode resonance portion 1042 is the largest, the bottom electrode protrusion portion 1041 is disposed along and connected to each side of the bottom electrode resonance portion 1042, and the projection of the bottom electrode protrusion portion 1041 on the bottom surface of the cavity 102 exposes the partial projection or the entire projection of the boundary of the top electrode recess portion 1081 connected by the top electrode bridging portion 1080 on the bottom surface of the cavity 102, the top electrode recess portion 1081 is disposed along and connected to each side of the top electrode resonance portion 1082, and the projection of the top electrode recess portion 1081 on the bottom surface of the cavity 102 exposes the partial projection or the entire projection of the boundary of the bottom electrode protrusion portion 1041 connected by the bottom electrode bridging portion 1040 on the bottom surface of the cavity 102, therefore, the bottom electrode convex part 1041 and the top electrode lapping part 1080 are not overlapped, the top electrode concave part 1081 and the bottom electrode lapping part 1040 are not overlapped, and the parasitic parameter can be reduced, in addition, the bottom electrode convex part 1041 and the top electrode concave part 1081 can be mutually staggered (the overlapped parts are not contacted) or even completely staggered, namely, at this time, the bottom electrode convex part 1041 and the top electrode concave part 1081 are partially aligned up and down in the direction vertical to the piezoelectric resonance layer 1051 but are not contacted or completely staggered, but all the parts are opposite in the peripheral direction of the piezoelectric resonance layer 1051, so that the bottom electrode convex part 1041 can partially surround the top electrode concave part 1081 in the projection structure towards the bottom surface of the cavity, thus, the cooperation of the bottom electrode convex part 1041 and the top electrode concave part 1081 can block the transverse wave of the whole periphery of the piezoelectric resonance layer 1051, moreover, the alignment requirements of the bottom electrode raised part 1041 and the top electrode recessed part 1081 can be reduced, which is beneficial to reducing the difficulty of the process manufacturing. For another example, referring to fig. 2C, the piezoelectric resonant layer 1051, the top electrode resonant portion 1082, and the bottom electrode resonant portion 1042 are all pentagonal planar structures, and the area of the piezoelectric resonant layer 1051 is the smallest, the areas, shapes, etc. of the top electrode resonant portion 1082 and the bottom electrode resonant portion 1042 are the same or substantially the same, the bottom electrode protrusion 1041 surrounds a circumference of the bottom electrode resonant portion 1042, the top electrode recess 1081 surrounds a circumference of the top electrode resonant portion 1082, and the projections of the bottom electrode protrusion 1041 and the top electrode recess 1081 on the bottom surface of the cavity 102 are overlapped, and the projections of the top electrode resonant portion 1082 and the bottom electrode resonant portion 1042 on the bottom surface of the cavity 102 are overlapped, so that the bottom electrode protrusion 1041 and the top electrode recess 1081 located at different heights in the vertical direction are all in a closed loop shape, thereby blocking transverse waves generated by the piezoelectric resonant layer 1051 at different heights. That is, when the bottom electrode raised portion 1041 extends to more continuous sides of the bottom electrode resonance portion 1042 and the top electrode recessed portion 1081 extends to more continuous sides of the top electrode resonance portion 1082, the bottom electrode raised portion 1041 and the top electrode recessed portion 1081 both extend around the peripheral direction of the piezoelectric resonance layer 1051, and the bottom electrode raised portion 1041 and the top electrode recessed portion 1081 respectively surround the periphery of the piezoelectric resonance layer 1051 in the peripheral direction of the piezoelectric resonance layer 1051 (as shown in fig. 2A-2B), at which time, both the top electrode recessed portion 1081 and the bottom electrode raised portion 1041 are at least partially opposed, or the bottom electrode raised portion 1041 and the top electrode recessed portion 1081 respectively surround the periphery of the piezoelectric resonance layer 1051 in the peripheral direction of the piezoelectric resonance layer 1051 (as shown in fig. 2C), at which time, all the portions of the top electrode raised portion 1081 and the bottom electrode raised portion 1041 are opposed.
Referring to fig. 2A to 2D, in the embodiments of the present invention, the bottom electrode bonding portion 1040 is electrically connected to at least one edge or at least one corner of the bottom electrode bump 1041 facing away from the bottom electrode resonance portion 1042, and extends from the corresponding edge of the bottom electrode bump 1041 to above a portion of the etching protection layer 101 at the periphery of the cavity 102 after suspending above the cavity (i.e., 102B) outside the bottom electrode bump 1041; the top electrode bonding portion 1080 is electrically connected to at least one edge or at least one corner of the top electrode recess 1081 facing away from the top electrode resonance portion 1082, and extends from the top electrode recess 1081 to the top of the partial etching protection layer 101 at the periphery of the cavity 102 after suspending above the cavity (i.e., 102B) at the outer side of the top electrode recess 1081, and the projections of the top electrode bonding portion 1080 and the bottom electrode bonding portion 1040 on the bottom surface of the cavity 102 may be directly connected to each other or separated from each other, so that the top electrode bonding portion 1080 and the bottom electrode bonding portion 1040 are not overlapped in the area of the cavity 102 and are staggered from each other. For example, as shown in fig. 1A and fig. 2A to 2C, the bottom electrode strap 1040 may extend only above a portion of the substrate at the periphery of one side of the cavity 102, the top electrode strap 1080 extends only above a portion of the substrate at the periphery of one side of the cavity 102, and the projections of the top electrode strap 1080 and the bottom electrode strap 1040 on the bottom surface of the cavity 102 are separated from each other, thereby avoiding the problems of parasitic parameters, leakage, short circuit and the like that may be caused when the top electrode strap 1080 and the bottom electrode strap 1040 are overlapped. Preferably, however, referring to fig. 2D, when the bottom electrode protruding portion 1041 is disposed along a plurality of continuous edges of the bottom electrode resonance portion 1042, the bottom electrode strap 1040 is disposed along all edges of the bottom electrode protruding portion 1041 facing away from the bottom electrode resonance portion 1042 and continuously extends onto the substrate at the periphery of the cavity 102, so that the bottom electrode strap 1040 can extend onto a portion of the substrate at more directions at the periphery of the cavity 102, that is, at this time, the bottom electrode strap 1040 completely covers the cavity 102 above the cavity portion where it is located, so that the support force for the film layer of the effective working area 102A can be enhanced by laying the bottom electrode strap 1040 with a large area, and the collapse of the cavity 102 can be prevented. Further preferably, when the bottom electrode strap 1040 extends above a portion of the substrate in more directions around the periphery of the cavity 102, the top electrode strap 1080 extends only above a portion of the substrate in one direction around the periphery of the cavity 102, for example, when the cavity 102 is rectangular in plan view, the top electrode strap 1080 extends only above the substrate around one side of the cavity 102, the bottom electrode strap 1040 extends to the other three sides of the cavity 102, and the top electrode strap 1080 and the bottom electrode strap 1040 are directly connected or separated from each other in projection onto the bottom surface of the cavity 102, that is, the bottom electrode strap 1040 completely covers the cavity 102 above the cavity portion where it is located, and does not overlap with the top electrode strap 1080 in the width direction of the top electrode strap 1080, so as to avoid the situation that the arrangement of the large-area top electrode strap may overlap with the structure such as the bottom electrode strap in the vertical direction to introduce excessive parasitic parameters, and further improve the electrical performance and reliability of the device.
In each embodiment of the present invention, when the cavity 102 has a polygonal top view shape, the bottom electrode overlapping portion 1040 and the top electrode overlapping portion 1080 respectively expose at least one side of the cavity, so that at least one end of each of the bottom electrode resonance portion 1042 connected to the bottom electrode protrusion 1041 and the top electrode resonance portion 1082 connected to the top electrode recess 1081 is completely suspended, which is beneficial to reducing the area of the inactive area 102B, further reducing parasitic parameters such as parasitic capacitance generated in the inactive area 102B, and improving device performance. Preferably, the bottom electrode raised portion 1041 is staggered with at least the top electrode overlapping portion 1080 above the cavity 102 (i.e. they do not overlap in the cavity area), the top electrode recessed portion 1081 is staggered with at least the bottom electrode overlapping portion 1040 above the cavity 102 (i.e. they do not overlap in the cavity area), and the projections of the top electrode recessed portion 1081 and the bottom electrode raised portion 1041 on the bottom surface of the cavity 102 are right in contact with each other or staggered with each other or have only partial overlap, so as to further reduce the parasitic parameters such as parasitic capacitance generated in the dead zone 102B and improve the device performance.
It should be noted that, in order to achieve the best transverse wave blocking effect and facilitate the fabrication of small-sized devices, the closer the top electrode concave portion 1081 and the bottom electrode convex portion 1041 are to the effective working area 102A, the better, the smaller the line widths of the top electrode concave portion 1081 and the bottom electrode convex portion 1041 are, the better, preferably, the line widths of the top electrode concave portion 1081 and the bottom electrode convex portion 1041 are respectively the minimum line widths allowed by the corresponding processes, and the horizontal distances between the top electrode concave portion 1081 and the bottom electrode convex portion 1041 and the effective working area 102A (i.e. the horizontal distance between the top electrode concave portion 1081 and the piezoelectric resonance layer 1051) are respectively the minimum distances allowed by the corresponding processes.
It is to be noted that, in the above embodiments, the top electrode resonance portion 1082 and the bottom electrode resonance portion 1042 have similar or identical shapes and have the same area, or the bottom electrode resonance portion 1042 has an area larger than that of the top electrode resonance portion 1082, but the technical solution of the present invention is not limited thereto, and in other embodiments of the present invention, the shapes of the top electrode resonance portion 1082 and the bottom electrode resonance portion 1042 may not be similar, but preferably, the shapes of the top electrode recess 1081 and the bottom electrode protrusion 1041 are adapted to the shape of the piezoelectric resonance layer 1051, which can extend along at least one side of the piezoelectric resonance layer 1051. In addition, it is found through research that most of the parasitic transverse waves of the bulk acoustic wave resonator are transmitted through the connection structure between the film layer on the effective working area 102A and the substrate at the periphery of the cavity, so in the embodiments of the present invention, on the premise of ensuring that the film layer of the effective working area 102A can be effectively supported, the area (or line width) of the top electrode overlapping portion 1080 can be controlled to be the smallest as possible, and the area (or line width) of the bottom electrode overlapping portion 1040 is the smallest.
An embodiment of the present invention further provides a filter, including at least one bulk acoustic wave resonator according to any of the embodiments of the present invention described above.
An embodiment of the present invention further provides a radio frequency communication system, including at least one filter according to an embodiment of the present invention.
Referring to fig. 3, an embodiment of the invention further provides a method for manufacturing a bulk acoustic wave resonator (for example, the bulk acoustic wave resonators shown in fig. 1A to 2D) of the invention, including:
s1, providing a substrate, and forming a first sacrificial layer with a sacrificial bulge on a part of the substrate;
s2, forming a bottom electrode layer on the first sacrificial layer, wherein the bottom electrode layer covers the part on the surface of the sacrificial bulge to form a bottom electrode bulge;
s3, forming a piezoelectric resonance layer on the bottom electrode layer, wherein the piezoelectric resonance layer exposes out of the bottom electrode bulge;
s4, forming a second sacrificial layer with a first groove in the area exposed around the piezoelectric resonance layer;
s5, forming a top electrode layer on the piezoelectric resonance layer and a part of the second sacrificial layer around the piezoelectric resonance layer, wherein the part of the top electrode layer covering the first groove forms a top electrode sunken part;
s6, removing the second sacrificial layer and the first sacrificial layer with the sacrificial bulges, wherein cavities are formed at the positions of the second sacrificial layer and the first sacrificial layer with the sacrificial bulges.
Referring to fig. 1A and 1B and fig. 4A to 4B, in step S1 of this embodiment, a first sacrificial layer is formed on a portion of a substrate by a process of forming a groove by etching the substrate and filling a material into the groove, and the specific implementation process includes:
first, referring to fig. 1A and fig. 4A, a substrate, specifically, a base 100 is provided, and an etching protection layer 101 is covered on the base 100. The etching protection layer 101 may be formed on the substrate 100 by any suitable process, such as a thermal treatment method, such as thermal oxidation, thermal nitridation or thermal oxynitridation, or a deposition method, such as chemical vapor deposition, physical vapor deposition or atomic layer deposition. Further, the thickness of the etching protection layer 101 may be set reasonably according to the actual device process requirements, and is not limited specifically herein.
Next, with continued reference to fig. 1A, 1B and 4A, the substrate is etched through photolithography and etching processes to form at least one second groove 102'. The etching process may be a wet etching or a dry etching process, wherein preferably a dry etching process is used, including but not limited to Reactive Ion Etching (RIE), ion beam etching, plasma etching or laser cutting. The depth and shape of the second groove 102' are determined by the depth and shape of the cavity required by the bulk acoustic wave resonator to be manufactured, the cross-sectional shape of the second groove 102' is rectangular, and in other embodiments of the present invention, the cross-section of the second groove 102' may be any other suitable shape, such as a circle, an ellipse, or other polygons (e.g., pentagon, hexagon, etc.) except for a rectangle.
Then, referring to fig. 1A, 1B and 4B, the first sacrificial layer 103 may be filled in the second groove 102' by processes of vapor deposition, thermal oxidation, spin coating or epitaxial growth, etc., where the first sacrificial layer 103 may be selected from a semiconductor material, a dielectric material or a photoresist material, etc., different from the substrate 100 and the etching protection layer 101, for example, when the substrate 100 is a Si substrate, the first sacrificial layer 103 may be Ge, and the formed first sacrificial layer 103 may further cover the etching protection layer 101 at the periphery of the groove or the top surface thereof is higher than the top surface of the etching protection layer 101 at the periphery of the groove; then, the top of the first sacrificial layer 103 is planarized to the top surface of the etching protection layer 101 by a Chemical Mechanical Planarization (CMP) process, so that the first sacrificial layer 103 is only located in the second groove 102', and the top surface of the first sacrificial layer 103 is flush with the top surface of the etching protection layer 101 around the first sacrificial layer 103, thereby providing a planar process surface for the subsequent process.
Next, a sacrificial material layer (not shown) may be covered on the first sacrificial layer 103 through a coating process, a vapor deposition process, or the like, wherein the thickness of the sacrificial material layer depends on the protruding height of the subsequently formed bottom electrode protrusion, and the material of the sacrificial material layer may be at least one selected from amorphous carbon, photoresist, dielectric material (e.g., silicon nitride, silicon oxycarbide, porous material, etc.), or semiconductor material (e.g., polysilicon, amorphous silicon, germanium), or the like; then, the sacrificial material layer is patterned by a photolithography process or a process combining photolithography and etching to form a sacrificial protrusion 103', and the line width, size, shape and position of the sacrificial protrusion 103' determine the line width, size, shape and position of a subsequently formed bottom electrode protrusion. In this embodiment, the longitudinal cross-section of the sacrificial protrusion 103' along XX ' in fig. 2A is a trapezoid with a narrow top and a wide bottom, and an included angle between the sidewall of the sacrificial protrusion 103' and the top surface of the first sacrificial layer 103
Less than 45 degrees, thereby facilitating the deposition of the subsequent bottom electrode material layer and further improving the thickness uniformity of the subsequently formed bottom electrode layer in the second groove 102' region. In other embodiments of the present invention, the cross-sectional shape of the sacrificial protrusion 103 'may also be a spherical cap with a narrow top and a wide bottom, i.e. its longitudinal cross-section along line XX' of fig. 1A is an inverted U-shape. The horizontal distance between the sacrificial protrusion 103' and the active working area 102A is preferably a minimum distance allowed by a process of etching alignment of the sacrificial protrusion 103', and a line width of the sacrificial protrusion 103' is a minimum line width allowed by a corresponding process.
In other embodiments of the present invention, the sacrificial protrusion 103 'and the first sacrificial layer 103 may be formed by the same process, for example, the first sacrificial layer 103 is covered on the second groove 102' and the etching protection layer 101, and the thickness of the first sacrificial layer 103 is not less than the sum of the depth of the second groove 102 'and the thickness of the sacrificial protrusion 103'; then, the first sacrificial layer 10 is patterned by an etching process to form the first sacrificial layer 103 only filled in the second groove 102', and a portion of the first sacrificial layer 103 has a sacrificial protrusion 103', a bottom surface of which may be flush with a top surface of the etching protection layer 101, and a remaining portion of the first sacrificial layer 103 has a top surface flush with the top surface of the etching protection layer 101.
Referring to fig. 1A, 1B and 4D, in step S2, first, a bottom electrode material layer (not shown) may be covered on the surfaces of the etching protection layer 101, the first sacrificial layer 103 and the sacrificial protrusion 103' by selecting a suitable method according to a material of a bottom electrode to be formed, for example, the bottom electrode material layer may be formed by a physical vapor deposition method such as magnetron sputtering and evaporation, or a chemical vapor deposition method; then, a photoresist layer (not shown) with a bottom electrode pattern defined thereon is formed on the bottom electrode material layer by using a photolithography process, the bottom electrode material layer is etched using the photoresist layer as a mask to form a bottom electrode layer (i.e., the remaining bottom electrode material layer) 104, and then the photoresist layer is removed. The bottom electrode material layer may use any suitable conductive material or semiconductor material known in the art, wherein the conductive material may be a metal material having a conductive property, such as one or more of aluminum (Al), copper (Cu), platinum (Pt), gold (Au), molybdenum (Mo), tungsten (W), iridium (Ir), osmium (Os), rhenium (Re), palladium (Pd), rhodium (Rh), and ruthenium (Ru), or a semiconductor material, such as Si, ge, siGe, siC, siGeC, or the like. In this embodiment, the bottom electrode layer (the remaining bottom electrode material layer) 104 includes a bottom electrode resonance portion 1042 covering the active working region 102A to be formed later, a bottom electrode bump 1041 covering the sacrificial protrusion 103', a bottom electrode overlap portion 1040 extending from one side of the bottom electrode bump 1041 to the outer side of the second recess 102' through the surface of the first sacrificial layer 103, and a bottom electrode peripheral portion 1043 separated from the bottom electrode resonance portion 1042 and the bottom electrode bump 1041, where the bottom electrode peripheral portion 1043 may be connected to a side of the bottom electrode bump 1041 facing away from the bottom electrode resonance portion 1042 to serve as a metal contact of the bulk acoustic wave resonator to be formed in the region, and may be separated from the bottom electrode overlap portion 1040 to serve as a part of the bottom electrode overlap portion of the adjacent bulk acoustic wave resonator, and in other embodiments of the present invention, the bottom electrode peripheral portion 1043 may be omitted. The bottom electrode resonator 1042 may be pentagonal in top view, and may also be quadrilateral or hexagonal in other embodiments of the present invention, a bottom electrode bump 1041 is disposed between the bottom electrode strap 1040 and the bottom electrode resonator 1042, the bottom electrode bump 1041 is disposed along at least one side of the bottom electrode resonator 1042 and is connected to a corresponding side of the bottom electrode resonator 1042, the bottom electrode strap 1040 is electrically connected to at least one side or at least one corner of the bottom electrode bump 1041 facing away from the bottom electrode resonator 1042, and extends from the corresponding side of the bottom electrode bump 1041 to a top surface of a partially etched protective layer 101 at the periphery of the second recess 102' after passing through a top surface of a first sacrificial layer 103 covering the outside of the bottom electrode bump 1041, that is, the bottom electrode bump 1041 is disposed along the side of the bottom electrode resonator 1042 and is disposed at least in an area where the bottom electrode strap 1040 and the bottom electrode resonator 1042 are aligned, for example, the bottom electrode bump 1041 may surround the bottom electrode resonator 1042, and at least one of the bottom electrode strap may be disposed along a closed loop resonator 1042 (see fig. 2, or two resonant structures as shown in the drawings (see fig. 2, the bottom electrode bump 1042 may also be disposed along a — 2). The shape, line width, horizontal distance from the active region 102A, and the like of the bottom electrode bump 1041 are determined by the forming process of the sacrificial bump 103'. Preferably, as shown in fig. 2D, the bottom electrode strap 1040 completely covers the cavity 102 above the cavity portion where it is located, and has no overlap with the top electrode strap 1080 in the width direction of the top electrode strap 1080, so as to improve the supporting force for the subsequent film layer and avoid the overlap with the top electrode strap 1080 as much as possible to introduce unnecessary parasitic parameters, for example, when the top view shape of the second groove 102' is a rectangle, the bottom electrode strap 1040 extends to three sides of the rectangle. The bottom electrode resonance section 1042 may function as an input electrode or an output electrode that receives or provides an electrical signal such as a Radio Frequency (RF) signal. In this embodiment, the bottom electrode bump 1041 has substantially the same thickness as the bottom electrode resonating section 1042 and the bottom electrode overlapping section 1040.
Referring to fig. 1A, 1B and 4E, in step S3, first, a piezoelectric material layer 105 may be deposited by any suitable method known to those skilled in the art, such as chemical vapor deposition, physical vapor deposition or atomic layer deposition; then, a photoresist layer (not shown) with a piezoelectric thin film pattern defined thereon is formed on the piezoelectric material layer 105 by a photolithography process, the piezoelectric material layer 105 is etched using the photoresist layer as a mask to form the piezoelectric resonance layer 1051, and then the photoresist layer is removed. As the material of the piezoelectric material layer 105, aluminum nitride (AlN), zinc oxide (ZnO), lead zirconate titanate (PZT), lithium niobate (LiNbO) can be used 3 ) Quartz (Quartz), potassium niobate (KNbO) 3 ) Or lithium tantalate (LiTaO) 3 ) And the like, and combinations thereof. When the piezoelectric material layer 105 includes aluminum nitride (AlN), the piezoelectric material layer 105 may further include a rare earth metal, for example, at least one of scandium (Sc), erbium (Er), yttrium (Y), and lanthanum (La). In addition, when the piezoelectric material layer 105 includes aluminum nitride (Al)AlN), the piezoelectric material layer 105 may further include a transition metal, for example, at least one of zirconium (Zr), titanium (Ti), manganese (Mn), and hafnium (Hf). The piezoelectric material layer 105 remaining after patterning includes a piezoelectric resonance layer 1051 and a piezoelectric peripheral portion 1050 that are separated from each other, the piezoelectric resonance layer 1051 is located on the bottom electrode resonance portion 1042, exposes the bottom electrode protrusion 1041, and may completely cover or partially cover the bottom electrode resonance portion 1042. The shape of the piezoelectric resonance layer 1051 may be the same as or different from that of the bottom electrode resonance section 1042, and the planar shape thereof may be pentagonal or other polygonal shapes such as a quadrangle, a hexagon, a heptagon, or an octagon. The piezoelectric peripheral portion 1050 can form a gap with the piezoelectric resonance layer 1051 to expose the bottom electrode protrusion 1041 and the first sacrificial layer 103 around the bottom electrode resonance portion 1042, and further limit a formation region of a subsequent second sacrificial layer by the formed gap, while providing a relatively flat process surface for formation of the subsequent second sacrificial protrusion, and the piezoelectric peripheral portion 1050 can also achieve isolation between a subsequently formed top electrode peripheral portion and a previously formed bottom electrode peripheral portion 1043, while providing a relatively flat process surface for formation of the subsequent second sacrificial layer and the top electrode layer.
Referring to fig. 1A, 1B and 4F, in step S4, first, a second sacrificial layer 106 may be covered in the piezoelectric periphery 1050, the piezoelectric resonance layer 1051 and the gap between the piezoelectric periphery 1050 and the piezoelectric resonance layer 1051 by a coating process or a vapor deposition process, and the second sacrificial layer 106 may fill the gap between the piezoelectric periphery 1050 and the piezoelectric resonance layer 1051, the material of the second sacrificial layer 106 may be at least one selected from amorphous carbon, photoresist, dielectric material (e.g. silicon nitride, silicon oxycarbide, porous material, etc.) or semiconductor material (e.g. polysilicon, amorphous silicon, germanium), and the material of the second sacrificial layer 106 is preferably different from that of the first sacrificial layer 103, so as to be able to utilize the top surface of the first sacrificial layer 103 as an etching stop point in the subsequent etching process for forming the first groove 107 and further control the depth of the subsequently formed first groove 107; then, the second sacrificial layer 106 is top-planarized by a CMP process so that the second sacrificial layer 106 is filled only in the gap between the piezoelectric periphery 1050 and the piezoelectric resonance layer 1051, and the piezoelectric periphery 1050, the piezoelectric resonance layer 1051, and the second sacrificial layer 106 constitute a flat upper surface. In other embodiments of the present invention, the second sacrificial layer 106 on the upper surfaces of the piezoelectric peripheral portion 1050 and the piezoelectric resonance layer 1051 may also be removed by an etch-back process so as to fill only the gap between the piezoelectric peripheral portion 1050 and the piezoelectric resonance layer 1051. Then, the second sacrificial layer 106 is patterned by photolithography or a process combining photolithography and etching to form a first groove 107, and the shape, size, position, and the like of the first groove 107 determine the shape, size, position, and the like of a subsequently formed top electrode recess. Preferably, the side wall of the first groove 107 is an inclined side wall inclined relative to the plane where the piezoelectric resonance layer 1051 is located, and included angles θ 1 and θ 2 between the side wall of the first groove 107 and the top surface of the piezoelectric resonance layer 1051 are both smaller than or equal to 45 degrees, so that the material coverage of the subsequent top electrode concave portion 1081 is facilitated, the occurrence of fracture is avoided, and the thickness uniformity is improved. Further preferably, the line width of the first groove 107 is the minimum line width allowed by the corresponding process, and the horizontal distance between the first groove 107 and the piezoelectric resonance layer 1051 is the minimum distance allowed by the corresponding process, thereby facilitating the reduction of the device size while achieving a better transverse wave blocking effect. In other embodiments of the present invention, when the first groove 107 and the sacrificial protrusion 103' do not have an overlapping portion in the vertical direction, after etching the second sacrificial layer 106, there may be a certain over-etching so that the bottom surface of the formed first groove 107 stops in the top surface or a certain thickness of the first sacrificial layer 103, thereby making it possible for the subsequently formed top electrode recess 1081 to complement the portion of the side of the bottom electrode recess 1041 not surrounding the piezoelectric resonance layer 1051, so that the combination of the top electrode recess 1081 and the bottom electrode recess 1041 may surround the piezoelectric resonance layer 1051. In other embodiments of the present invention, the cross-sectional shape of the first groove 107 may also be a spherical cap with a wide top and a narrow bottom, i.e. its longitudinal cross-section along line XX' of fig. 1A is U-shaped.
In other embodiments of the present invention, the second sacrificial layer 106 includes a first sub-sacrificial layer (not shown) and a second sub-sacrificial layer (not shown) which are made of different materials and stacked from bottom to top, and the arrangement of the first sub-sacrificial layer and the second sub-sacrificial layer enables a stop point of etching to be precisely controlled when a first groove is formed by etching, so as to precisely control a recess depth of a subsequently formed top electrode recess 1081, and thus, a thickness of the second sub-sacrificial layer determines a recess depth of the subsequently formed top electrode recess 1081. Wherein the second sacrificial layer 106 having the first sub-sacrificial layer, the second sub-sacrificial layer and the first groove 107 may be formed by the following steps including: firstly, filling a first sub sacrificial layer in a gap between the piezoelectric resonance layer 1051 and the piezoelectric periphery 1050 by a vapor deposition or epitaxial growth process, wherein the first sub sacrificial layer is made of a material which can be converted into another material after being processed by some processes, in this embodiment, the first sub sacrificial layer may be a semiconductor material, and is formed in the gap by a chemical vapor deposition process, and at this time, the first sub sacrificial layer not only fills the gap between the piezoelectric resonance layer 1051 and the piezoelectric periphery 1050, but also covers the upper surfaces of the piezoelectric resonance layer 1051 and the piezoelectric periphery 1050; then, the top of the first sub-sacrificial layer is planarized to the top surfaces of piezoelectric resonance layer 1051 and piezoelectric peripheral portion 1050 by a Chemical Mechanical Planarization (CMP) process so that the first sub-sacrificial layer is located only in the gap between piezoelectric resonance layer 1051 and piezoelectric peripheral portion 1050; then, selecting a suitable surface modification treatment process according to the material of the first sub-sacrificial layer, for example, including at least one of oxidation treatment, nitridation treatment and ion implantation, and performing surface modification treatment on the top of the first sub-sacrificial layer to a certain thickness, so that the first sub-sacrificial layer with the certain thickness is converted into a second sub-sacrificial layer of another material, where the second sub-sacrificial layer and the remaining first sub-sacrificial layer below the second sub-sacrificial layer, which is not subjected to the surface modification treatment, form a second sacrificial layer 106 that fills up the gap between the piezoelectric resonance layer 1051 and the piezoelectric peripheral portion 1050, and the thickness of the second sub-sacrificial layer depends on the recess depth of a top electrode recess 1081 to be formed subsequently; thereafter, since the surface treatment process may make the top surface of the filled second sacrificial layer 106 no longer flush with the top surface of the piezoelectric resonator layer 1051 around the filled second sacrificial layer, which is not favorable for the deposition of the subsequent top electrode layer 108, it is necessary to further planarize the top of the second sub-sacrificial layer to the top surface of the piezoelectric resonator layer 1051 through a Chemical Mechanical Planarization (CMP) process, so that the top surface of the second sacrificial layer 106 is flush with the top surface of the piezoelectric resonator layer 1051 around the filled second sacrificial layer again, so as to provide a relatively flat operation surface for the subsequent process. Then, the second sub-sacrificial layer in the periphery of the second sacrificial layer 106 corresponding to the effective working area (e.g., 102A in fig. 4H) of the bulk acoustic wave resonator to be manufactured may be etched by a process of photolithography and etching, and the etching may be stopped at the top surface of the first sub-sacrificial layer, or may be performed with a certain over-etching so as to be stopped in the first sub-sacrificial layer, thereby forming the first groove 107.
Referring to fig. 1A, fig. 1B and fig. 4G, in step S5, first, a top electrode material layer (not shown) may be coated on the surfaces of the piezoelectric periphery 1050, the piezoelectric resonator layer 1051, the second sacrificial layer 106 and the first groove 107 by a suitable method according to a material of a top electrode to be formed, for example, the top electrode material layer may be formed by a physical vapor deposition method such as magnetron sputtering or evaporation, or a chemical vapor deposition method, and the top electrode material layer may have a uniform thickness at each position; then, a photoresist layer (not shown) with a top electrode pattern defined thereon is formed on the top electrode material layer by using a photolithography process, the top electrode material layer is etched using the photoresist layer as a mask to form a top electrode layer (i.e., the patterned top electrode material layer or the remaining top electrode material layer) 108, and then the photoresist layer is removed. The top electrode material layer may use any suitable conductive material or semiconductor material known in the art, wherein the conductive material may be a metal material with conductive property, such as one or more of Al, cu, pt, au, mo, W, ir, os, re, pd, rh, and Ru, and the semiconductor material may be Si, ge, siGe, siC, siGeC, etc. In this embodiment, the top electrode layer 108 includes a top electrode resonance portion 1082 covering the piezoelectric resonance layer 1051, a top electrode recess 1081 covering the first groove 107, a top electrode lap 1080 extending from the top electrode recess 1081 through a part of the top surface of the second sacrificial layer 106 to the piezoelectric peripheral portion 1050 outside the top electrode recess 1081, and a top electrode peripheral portion 1083 separated from both the top electrode resonance portion 1082 and the top electrode recess 1081, the top electrode peripheral portion 1083 may be connected to a side of the top electrode lap 1080 facing away from the top electrode resonance portion 1082 to serve as one metal contact of the bulk acoustic wave resonator to be formed in the area, and may be separated from the top electrode lap 1080 to serve as a part of the top electrode lap of an adjacent bulk acoustic wave resonator, and in other embodiments of the present invention, the top electrode peripheral portion 1083 may be omitted. The top electrode resonance portion 1082 may have the same or different top view shape as that of the piezoelectric resonance layer 1051, for example, a pentagonal top view shape, and preferably has an area larger than that of the piezoelectric resonance layer 1051, so that the piezoelectric resonance layer 1051 is completely sandwiched by the top electrode resonance portion 1082 and the bottom electrode resonance portion 1042, thereby facilitating reduction of the device size and parasitic parameters. The top electrode layer 108 may serve as an input electrode or an output electrode that receives or provides electrical signals, such as Radio Frequency (RF) signals. For example, when the bottom electrode layer 104 is used as an input electrode, the top electrode layer 108 may be used as an output electrode, and when the bottom electrode layer 104 is used as an output electrode, the top electrode layer 108 may be used as an input electrode, and the piezoelectric resonance layer 1051 converts an electric signal input through the top electrode resonance portion 1082 or the bottom electrode resonance portion 1042 into a bulk acoustic wave. For example, the piezoelectric resonance layer 1051 converts an electric signal into a bulk acoustic wave by physical vibration. The top electrode recessed portion 1081 is disposed along at least one side of the top electrode resonance portion 1082 and connected to a corresponding side of the top electrode resonance portion 1082, i.e., the top electrode recessed portion 1081 is disposed along the side of the top electrode resonance portion 1082 and at least disposed in an area where the top electrode lap 1080 and the top electrode resonance portion 1082 are aligned, e.g., the top electrode recessed portion 1081 surrounds the top electrode resonance portion 1082 for a circle to form a closed loop structure (as shown in fig. 2C and 2D, 2F), while the portion where the top electrode recessed portion 1081 overlaps the bottom electrode raised portion 1041 has a gap H therebetween without contacting, e.g., the top electrode recessed portion 1081 extends on a plurality of continuous sides of the top electrode resonance portion 1082 to form an open loop structure (as shown in fig. 2A and 2B). The top electrode strap 1080 is electrically connected to a side of the top electrode recess 1081 facing away from the top electrode resonance portion 1082, and extends from the top electrode recess 1081 to a top surface of a portion of the etching protection layer 101 outside the second groove 102 'through a top surface of a portion of the second sacrificial layer 106, the top electrode strap 1080 and the bottom electrode strap 1040 are staggered with respect to each other (i.e., they do not overlap in a region of the cavity 102), and the top electrode strap 1080 and the bottom electrode strap 1040 respectively expose at least one side of the second groove 102'. In an embodiment of the invention, referring to fig. 2A and 2B, in a direction perpendicular to the bottom surface of the second groove 102', the top electrode recess 1081 and the bottom electrode lap 1040 do not overlap with a side of the bottom electrode bump 1041 facing, and the bottom electrode bump 1041 and the top electrode lap 1080 are not overlapped with a side of the top electrode recess 1081 facing. The projections of the top electrode strap 1080 and the bottom electrode strap 1040 on the bottom surface of the second recess 102 'are directly connected or separated from each other, and the top electrode strap 1080 may extend only over a portion of the substrate at the periphery of one side of the second recess 102'.
Referring to fig. 1A, 1B and 4H, in step S6, holes may be punched at the edge of the piezoelectric peripheral portion 1050 facing the second groove 102' or at the periphery of the device region of the bulk acoustic wave resonator by a photolithography combined with an etching process or a laser cutting process to form release holes (not shown) capable of exposing at least one of a portion of the sacrificial protrusion 103', a portion of the first sacrificial layer 103 other than the sacrificial protrusion 103', and a portion of the second sacrificial layer 106; then, gas and/or liquid medicine is introduced into the release hole to remove the second sacrificial layer 106 and the first sacrificial layer 103 having the sacrificial protrusion 103', and the second recess is emptied again to form a cavity 102, where the cavity 102 includes a space of the second recess 102' increased by the bottom electrode protrusion 1041, a space limited by the top electrode recess 1081, and spaces originally occupied by the second sacrificial layer 106 at two sides below the top electrode recess 1081. Among them, the bottom electrode resonance portion 1042, the piezoelectric resonance layer 1051, and the top electrode resonance portion 1082 suspended above the cavity 102 and stacked in order constitute an individual stereo film, and a portion where the bottom electrode resonance portion 1042, the piezoelectric resonance layer 1051, the top electrode resonance portion 1082, and the cavity 102 are overlapped with each other along a vertical direction is an effective area defined as an effective working area 102A, in which, when electric power such as a radio frequency signal is applied to the bottom electrode resonance portion 1042 and the top electrode resonance portion 1082, vibration and resonance are generated in a thickness direction (i.e., a longitudinal direction) of the piezoelectric resonance layer 1051 due to a piezoelectric phenomenon generated in the piezoelectric resonance layer 1051, and other areas of the cavity 102 are inactive areas 102B, in which, even when electric power is applied to the top electrode layer 108 and the bottom electrode layer 104, an area that is not resonated due to the piezoelectric phenomenon is not generated in the inactive area 102B. The independent acoustic thin film composed of the bottom electrode resonance portion 1042, the piezoelectric resonance layer 1051, and the top electrode resonance portion 1082 suspended above the effective working area 102A and stacked in this order can output a radio frequency signal of a resonance frequency corresponding to the vibration of the piezoelectric phenomenon of the piezoelectric resonance layer 1051. Specifically, when electric power is applied to the top electrode resonance portion 1082 and the bottom electrode resonance portion 1042, a bulk acoustic wave is generated by a piezoelectric phenomenon generated in the piezoelectric resonance layer 1051. In this case, the generated bulk acoustic wave has a parasitic transverse wave in addition to the desired longitudinal wave, and the transverse wave is blocked at the top electrode recess 1081 and the bottom electrode protrusion 1041, and the transverse wave is confined in the active region 102A and prevented from propagating into the film layer at the periphery of the cavity, thereby improving acoustic loss caused by propagation of the transverse wave into the film layer at the periphery of the cavity, so that the quality factor of the resonator is improved, and finally the device performance can be improved.
It should be noted that step S6 may be performed after all the film layers above the cavity 102 to be formed are manufactured, so that the first sacrificial layer 103 and the second sacrificial layer 106 may be continuously utilized to protect the space where the cavity 102 is located and the stacked film layer structure formed thereon from the bottom electrode layer 104 to the top electrode layer 108, so as to avoid the risk of cavity collapse caused by continuing the subsequent processes after the cavity 102 is formed. In addition, the release hole formed in step S6 may be left all the time, so that the release hole can be sealed by a subsequent packaging process such as two-substrate bonding, and the cavity 102 is closed.
It should be noted that, in step S1 of the manufacturing method of the bulk acoustic wave resonator in each of the above embodiments, the first sacrificial layer is formed on a portion of the substrate by a process of etching the substrate to form the second groove 102' and filling the second groove 102', so that the cavity 102 formed in step S6 is a groove structure in which the whole bottom is recessed in the substrate, but the technical solution of the present invention is not limited thereto, and in step S1 of other embodiments of the present invention, the first sacrificial layer 103 protruding over the substrate as a whole may be formed by film deposition in combination with photolithography and etching processes, so that the cavity formed in step S6 is a cavity structure protruding over the surface of the substrate as a whole, specifically, referring to fig. 2E and fig. 5, in step S1, the groove 102' for forming the cavity is not formed in the provided substrate, but the etching protection layer 101 on the surface of the substrate 100 is covered with the first sacrificial layer 103; then, the first sacrificial layer 103 is patterned by a process of photolithography and etching, only the first sacrificial layer 103 covering the region 102 remains, and then the first sacrificial layer 103 is disposed on a portion of the substrate, the first sacrificial layer 103 may be a structure with a narrow top and a wide bottom, after the thickness of the first sacrificial layer 103 determines the depth of the cavity 102 to be formed subsequently, a sacrificial material layer for forming a sacrificial protrusion 103 'is covered on the first sacrificial layer 103 and the substrate, and then the sacrificial protrusion 103' is formed on a portion of the first sacrificial layer 103 by a process of photolithography and etching. In this embodiment, the subsequent steps are completely the same as those of the corresponding parts in the method for manufacturing the bulk acoustic wave resonator of the embodiment shown in fig. 4A to 4H, and are not repeated herein, except that the corresponding sidewalls of the formed bottom electrode peripheral portion 1043, the bottom electrode bridging portion 1040, the piezoelectric peripheral portion 1050, the top electrode peripheral portion 1083, and the top electrode bridging portion 1080 need to be deformed to adapt to the protruding first sacrificial layer 103, and the longitudinal cross section of each of the sidewalls is changed into a "Z" shaped structure.
The bulk acoustic wave resonator of the present invention preferably employs the method for manufacturing a bulk acoustic wave resonator of the present invention, so that the bottom electrode lap joint portion, the bottom electrode protrusion portion and the bottom electrode resonance portion are manufactured together, and the top electrode lap joint portion, the top electrode recess portion and the top electrode resonance portion are manufactured together, thereby simplifying the process and reducing the manufacturing cost.
It will be apparent to those skilled in the art that various changes and modifications may be made in the invention without departing from the spirit and scope of the invention. Thus, if such modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include such modifications and variations.
Claims (13)
1. A method of manufacturing a bulk acoustic wave resonator, comprising:
providing a substrate, and forming a first sacrificial layer with a sacrificial bulge on a part of the substrate;
forming a bottom electrode layer on the first sacrificial layer, wherein the bottom electrode layer covers the part on the surface of the sacrificial protrusion to form a bottom electrode protrusion part;
forming a piezoelectric resonance layer on the bottom electrode layer, wherein the piezoelectric resonance layer exposes the bottom electrode bulge;
forming a second sacrificial layer with a first groove in an exposed area around the piezoelectric resonance layer;
forming a top electrode layer on the piezoelectric resonance layer and a part of the second sacrificial layer around the piezoelectric resonance layer, wherein the part of the top electrode layer covering the first groove forms a top electrode recess;
and removing the second sacrificial layer and the first sacrificial layer with the sacrificial protrusions, wherein cavities are formed at the positions of the second sacrificial layer and the first sacrificial layer with the sacrificial protrusions, the top electrode concave part and the bottom electrode convex part are both positioned in the cavity region at the periphery of the piezoelectric resonance layer, and the bottom electrode convex part and the top electrode concave part both extend around the peripheral direction of the piezoelectric resonance layer and are at least partially opposite to each other.
2. The method of manufacturing a bulk acoustic wave resonator according to claim 1, wherein the step of forming a first sacrificial layer having a sacrificial protrusion on a portion of the substrate includes: etching the substrate to form a groove in the substrate; forming a first sacrificial layer to fill in the groove; covering a sacrificial material layer on the first sacrificial layer and the substrate, and patterning the sacrificial material layer to form a sacrificial bulge which is arranged on part of the first sacrificial layer in a protruding mode;
the step of forming a first sacrificial layer having sacrificial protrusions on a portion of a substrate includes: covering a first sacrificial layer on the substrate; patterning the first sacrificial layer to form a first sacrificial layer protruding from a part of the substrate; covering a sacrificial material layer on the first sacrificial layer and the substrate, and patterning the sacrificial material layer to form a sacrificial protrusion protruding on a part of the first sacrificial layer.
3. The method of manufacturing a bulk acoustic wave resonator according to claim 1, wherein the step of removing the second sacrificial layer and the first sacrificial layer having the sacrificial projections includes:
after forming the top electrode layer, forming at least one release hole, wherein the release hole at least exposes a part of the second sacrificial layer, a part of the sacrificial protrusion or a part of the first sacrificial layer except the sacrificial protrusion;
and introducing gas and/or liquid medicine into the release hole to remove the second sacrificial layer and the first sacrificial layer with the sacrificial protrusion.
4. The method of manufacturing a bulk acoustic wave resonator according to any one of claims 1 to 3, wherein the step of forming the bottom electrode layer includes: depositing a bottom electrode material layer to cover the first sacrificial layer with the sacrificial protrusion; and patterning the bottom electrode material layer to form a bottom electrode overlapping part, a bottom electrode protruding part and a bottom electrode resonance part which are sequentially connected, wherein the bottom electrode resonance part is overlapped with the piezoelectric resonance layer, and one end, back to the bottom electrode protruding part, of the bottom electrode overlapping part is overlapped on the substrate on the periphery of the cavity.
5. The method of manufacturing a bulk acoustic wave resonator according to claim 4, wherein the step of forming the top electrode layer includes: depositing a top electrode material layer to cover the second sacrificial layer with the first groove and the piezoelectric resonance layer; patterning the top electrode material layer to form a top electrode overlapping part, a top electrode depressed part and a top electrode resonance part which are connected in sequence, wherein the top electrode resonance part is overlapped with the piezoelectric resonance layer, one end of the top electrode overlapping part, which faces away from the top electrode depressed part, extends to the upper part of the substrate on the periphery of the cavity, and the top electrode overlapping part and the bottom electrode overlapping part are staggered with each other.
6. The method of manufacturing a bulk acoustic wave resonator according to claim 5, wherein the bottom electrode resonance section and the top electrode resonance section are each polygonal, the bottom electrode protrusion section is provided along a side of the bottom electrode resonance section and at least in a region where the bottom electrode lap section and the bottom electrode resonance section are aligned, and the top electrode recess section is provided along a side of the top electrode resonance section and at least in a region where the top electrode lap section and the top electrode resonance section are aligned.
7. The method of manufacturing a bulk acoustic wave resonator according to any one of claims 1 to 3 and 5 to 6, wherein a horizontal distance between the bottom electrode-protrusion and the piezoelectric resonance layer is a minimum distance allowed by a process of manufacturing the bottom electrode-protrusion; the horizontal distance between the top electrode recess and the piezoelectric resonance layer is a minimum distance allowed by a process of manufacturing the top electrode recess.
8. The method of manufacturing a bulk acoustic wave resonator according to any one of claims 1 to 3 and 5 to 6, wherein a line width of the bottom electrode bump is a minimum line width allowed by a process of manufacturing the bottom electrode bump; the line width of the top electrode recess is the minimum line width allowed by the process for manufacturing the top electrode recess.
9. The method of manufacturing a bulk acoustic wave resonator according to claim 6, wherein the bottom electrode bump is staggered from at least the top electrode lap above the cavity, or the bottom electrode bump is looped around the bottom electrode resonance portion; the top electrode sunken part is at least staggered with the bottom electrode overlapping part above the cavity, or the top electrode sunken part surrounds the top electrode resonance part for a circle.
10. The method for manufacturing a bulk acoustic wave resonator according to claim 9, wherein projections of the top electrode recess and the bottom electrode projection on the bottom surface of the cavity are right in contact with each other or are staggered with each other or have an overlap.
11. The method of manufacturing a bulk acoustic wave resonator according to claim 6, wherein the bottom electrode lap completely covers the cavity above the cavity portion where it is located, and does not overlap with the top electrode lap in a width direction of the top electrode lap.
12. The method of manufacturing a bulk acoustic wave resonator according to claim 6, wherein the side wall of the top electrode recess is inclined with respect to the top surface of the piezoelectric resonance layer, and the side wall of the bottom electrode projection is inclined with respect to the bottom surface of the piezoelectric resonance layer.
13. The method of manufacturing a bulk acoustic wave resonator according to claim 12, wherein an angle between a side wall of the top electrode recess and the top surface of the piezoelectric resonance layer is 45 degrees or less, and an angle between a side wall of the bottom electrode projection and the bottom surface of the piezoelectric resonance layer is 45 degrees or less.
Priority Applications (4)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201910273072.6A CN111786654B (en) | 2019-04-04 | 2019-04-04 | Bulk acoustic wave resonator, method of manufacturing the same, filter, and radio frequency communication system |
| JP2021525804A JP7194475B2 (en) | 2019-04-04 | 2019-09-10 | Bulk acoustic wave resonator, manufacturing method thereof, filter, radio frequency communication system |
| PCT/CN2019/105093 WO2020199509A1 (en) | 2019-04-04 | 2019-09-10 | Bulk acoustic wave resonator and manufacturing method therefor, filter and radio-frequency communication system |
| US17/449,836 US20220029603A1 (en) | 2019-04-04 | 2021-10-04 | Bulk acoustic wave resonator, filter and radio frequency communication system |
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| US8981876B2 (en) | 2004-11-15 | 2015-03-17 | Avago Technologies General Ip (Singapore) Pte. Ltd. | Piezoelectric resonator structures and electrical filters having frame elements |
| JP2006211296A (en) | 2005-01-28 | 2006-08-10 | Sony Corp | Method of manufacturing micro machine, and micro machine |
| JP4870541B2 (en) | 2006-12-15 | 2012-02-08 | 太陽誘電株式会社 | Piezoelectric thin film resonator and filter |
| JP5080858B2 (en) * | 2007-05-17 | 2012-11-21 | 太陽誘電株式会社 | Piezoelectric thin film resonator and filter |
| JP2009124640A (en) | 2007-11-19 | 2009-06-04 | Hitachi Media Electoronics Co Ltd | Thin-film piezoelectric bulk wave resonator and its manufacturing method, and thin-film piezoelectric bulk wave resonator filter using thin-film piezoelectric bulk wave resonator |
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| US9520855B2 (en) * | 2014-02-26 | 2016-12-13 | Avago Technologies General Ip (Singapore) Pte. Ltd. | Bulk acoustic wave resonators having doped piezoelectric material and frame elements |
| JP6743830B2 (en) * | 2015-12-11 | 2020-08-19 | 株式会社村田製作所 | Elastic wave device |
| KR20180018149A (en) * | 2016-08-12 | 2018-02-21 | 삼성전기주식회사 | Bulk acoustic wave resonator |
| US10903814B2 (en) * | 2016-11-30 | 2021-01-26 | Samsung Electro-Mechanics Co., Ltd. | Bulk acoustic wave resonator |
| US11476826B2 (en) * | 2017-01-17 | 2022-10-18 | Samsung Electro-Mechanics Co., Ltd. | Bulk acoustic wave resonator |
| KR102345116B1 (en) * | 2017-03-23 | 2021-12-30 | 삼성전기주식회사 | Acoustic resonator and manufacturing method thereof |
| KR102052795B1 (en) * | 2017-03-23 | 2019-12-09 | 삼성전기주식회사 | Acoustic resonator |
| KR102369434B1 (en) * | 2017-04-19 | 2022-03-03 | 삼성전기주식회사 | Bulk-acoustic wave resonator and method for manufacturing the same |
| US11057017B2 (en) * | 2017-08-17 | 2021-07-06 | Samsung Electro-Mechanics Co., Ltd | Bulk-acoustic wave resonator |
| CN108134589B (en) * | 2018-02-05 | 2020-02-18 | 武汉衍熙微器件有限公司 | Film bulk acoustic resonator |
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| CN111786654A (en) | 2020-10-16 |
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