JP2022507306A - Bulk acoustic wave resonator and its manufacturing method, filter, radio frequency communication system - Google Patents

Abstract

A bulk acoustic wave resonator, a method for manufacturing the same, a filter, and a radio frequency communication system, wherein the bottom electrode protrusion (1041) is formed on the outer periphery of the piezoelectric resonance layer (1051) and floats above the cavity (102). And the top electrode recess (1081) can block the lateral wave generated by the piezoelectric resonance layer (1051) from being transferred to the outer periphery of the cavity (102), and can reflect the transverse wave to the effective operating region (102A). Further, the loss of acoustic waves can be reduced, the quality coefficient of the resonator can be improved, and finally the performance of the device can be improved. Further, the bottom electrode bridge portion (1040) and the portion where the top electrode bridge portion (1080) and the cavity (102) overlap each other are floating, and the bottom electrode bridge portion (1040) and the top electrode bridge portion (1080) are combined. Can be displaced from each other, significantly reducing parasitic parameters, avoiding problems such as leaks and short circuits, and improving device reliability. [Selection diagram] FIG. 1B

Description

The present invention relates to the technical field of radio frequency communication, and particularly to a bulk acoustic wave resonator, a method for manufacturing the same, a filter, and a radio frequency communication system.

Radio frequency (RF) communications, such as those used in mobile phones, must use radio frequency filters, each of which transmits the required frequency and limits all other frequencies. Can be done. With the development of mobile communication technology, the amount of mobile data transferred is also increasing rapidly. Therefore, it is not possible to improve the transmission power of wireless power transfer devices such as radio base stations, micro base stations or repeaters, assuming that frequency resources are limited and it is necessary to use as few mobile communication devices as possible. This is a problem to be considered, and it also means that the demand for filter power in the front-end circuit of the mobile communication device is high.

Conventionally, high power filters in devices such as radio base stations mainly consist of cavity filters, the power of which reaches 100 watts, but the size of such filters is too large. Some devices use a dielectric filter, the average power of which can reach 5 watts or more, and the size of this filter is also large. Due to their large size, these two filters cannot be integrated into a radio frequency front-end chip.

As MEMS technology matures, filters composed of bulk acoustic wave (BAW) resonators can successfully overcome the existing flaws of the two filters described above. Bulk acoustic wave resonators have volume advantages that cannot be compared with ceramic dielectric filters, and operating frequency and power capacitance advantages that cannot be compared with surface acoustic wave (SAW) resonators. It has become.

The main body of the bulk acoustic wave resonator has a "sandwich" structure consisting of a bottom electrode, a piezoelectric thin film, and a top electrode, and uses the inverse piezoelectric effect of the piezoelectric thin film to convert electrical energy into mechanical energy and bulk it. A stationary wave is formed in the form of an acoustic wave in a filter composed of an acoustic wave resonator. Since the velocity of the acoustic wave is five orders of magnitude smaller than that of the electromagnetic wave, the size of the filter configured by the bulk acoustic wave resonator is smaller than that of a conventional dielectric filter or the like.

The operating principle of one of these cavity-type bulk acoustic wave resonators is to use acoustic waves to reflect at the intersection of the bottom electrode or support layer and air, limiting the acoustic waves to the piezoelectric layer and achieving resonance. It has advantages such as high Q value, low insertion loss, and can be integrated, and is widely adopted.

However, the conventionally manufactured cavity type bulk acoustic wave resonator cannot further improve its quality coefficient (Q) and cannot meet the demand for a high-performance radio frequency system.

It is an object of the present invention to provide a bulk acoustic wave resonator, a manufacturing method thereof, a filter, and a radio frequency communication system capable of improving the quality coefficient and further improving the performance of the device.

In order to achieve the above object, according to the present invention,
With the board
A bottom electrode layer provided on the substrate, in which a cavity is formed between the bottom electrode layer and the substrate, and the bottom electrode layer is located in the region of the cavity and is separated from the bottom surface of the cavity. A bottom electrode layer having a bottom electrode protrusion protruding in the direction,
A piezoelectric resonance layer formed on the bottom electrode layer above the cavity,
A top electrode layer formed on the piezoelectric resonance layer, wherein the top electrode layer is located in the region of the cavity and has a top electrode recessed portion recessed in a direction close to the bottom surface of the cavity. The top electrode recess and the bottom electrode protrusion are both located in the cavity region on the outer periphery of the piezoelectric resonance layer, and the bottom electrode protrusion and the top electrode recess both surround the piezoelectric resonance layer. A bulk acoustic wave resonator is provided that extends in the peripheral direction and includes a top electrode layer that is at least partially opposed to each other.

The present invention further provides a filter comprising at least one bulk acoustic wave resonator according to the present invention.

The present invention further provides a radio frequency communication system comprising at least one filter according to the present invention.

Further, according to the present invention,
A step of providing a substrate and forming a first sacrificial layer with sacrificial protrusions on some of the substrates.
A step of forming a bottom electrode layer on the first sacrificial layer and forming a portion of the bottom electrode layer covering the surface of the sacrificial protrusion as a bottom electrode protrusion.
A step of forming a piezoelectric resonance layer that exposes the bottom electrode protrusion on the bottom electrode layer,
A step of forming a second sacrificial layer having a first groove in an exposed region around the piezoelectric resonance layer.
The top electrode layer is formed on the piezoelectric resonance layer and a part of the second sacrificial layer around the piezoelectric resonance layer, and the portion of the top electrode layer covering the first groove is used as a top electrode recess. Steps to form and
It is a step of removing the second sacrificial layer and the first sacrificial layer having the sacrificial protrusion, and forming a cavity at the position of the second sacrificial layer and the first sacrificial layer having the sacrificial protrusion. The top electrode recess and the bottom electrode protrusion are both located in the cavity region on the outer periphery of the piezoelectric resonance layer, and the bottom electrode protrusion and the bottom electrode recess both form the piezoelectric resonance layer. A method of manufacturing a bulk acoustic wave resonator is provided that includes a step extending in the enclosed peripheral direction and at least partially opposed to each other.

Compared with the prior art, the technical solution of the present invention has the following beneficial effects.
1. When electrical energy is applied to the bottom and top electrodes, the piezoelectric phenomenon that occurs in the piezoelectric resonance layer produces desirable longitudinal waves that propagate in the thickness direction and unwanted transverse waves that propagate along the plane of the piezoelectric resonance layer. The transverse wave is blocked by the bottom electrode protrusion and the top electrode recess on the cavity floating on the outer periphery of the piezoelectric resonance layer, reflected in the region corresponding to the piezoelectric resonance layer, and the transverse wave is further applied to the film layer on the outer periphery of the cavity. The loss due to propagation in can be reduced, thereby improving acoustic wave loss, improving the quality factor of the resonator, and ultimately improving the performance of the device.

2. The periphery of the piezoelectric resonance layer and the periphery of the cavity are separated from each other, that is, the piezoelectric resonance layer does not continuously extend above the substrate on the outer periphery of the cavity, and the bulk acoustic wave resonator is effectively operated. The region can be completely restricted to the cavity region, with both the bottom and top electrode bridges extending to only some sides of the cavity (ie, the bottom and top electrode layers). Does not completely cover the cavity), thereby reducing the effect of the film layer around the cavity on the longitudinal vibrations generated in the piezoelectric resonant layer and improving performance.

3. Even if the protruding portion of the bottom electrode and the recessed portion of the top electrode have a portion that overlaps with each other, there is a gap structure between the overlapping portions, which can significantly reduce the parasitic parameters and the top electrode layer. And problems such as electrical contact in the cavity region of the bottom electrode layer can be avoided and the reliability of the device can be improved.

4. The bottom electrode bridge portion and the portion where the top electrode bridge portion and the cavity overlap are both floating, and the bottom electrode bridge portion and the top electrode bridge portion are displaced from each other (that is, the cavity region). Both do not overlap in the cavity region), which can significantly reduce parasitic parameters and avoid problems such as leaks and short circuits caused by contact between the bottom electrode bridge and the top electrode bridge. , The reliability of the device can be improved.

5. The bottom electrode bridge portion completely covers the cavity above a part of the cavity in which it is located, thereby being strong against the membrane layer above it using a large area bottom electrode bridge portion. Provides good mechanical support, thereby avoiding the problem of device expiration due to cavity collapse.

6. The recessed portion of the top electrode surrounds the entire circumference of the resonance portion of the top electrode, the protruding portion of the bottom electrode surrounds the entire circumference of the resonance portion of the bottom electrode, and the transverse wave is blocked from the periphery of the piezoelectric resonance layer in all directions, which is a more preferable quality coefficient. Can be obtained.

7. The bottom electrode protrusion, the bottom electrode resonance part and the bottom electrode bridge part are formed of the same film layer and have a uniform film thickness, and the top electrode recess, the top electrode resonance part and the top electrode bridge part are the same film. It is formed of layers and has a uniform film thickness, which simplifies the process and reduces costs, and the film thickness of the bottom electrode protrusion is about the same as the rest of the bottom electrode layer. Since the film thickness of the electrode recess is almost the same as that of the other parts of the top electrode layer, the reliability of the device can be improved without the situation where the bottom electrode protrusion and the top electrode recess are cut. Can be done.

It is a top surface structure schematic diagram of the bulk acoustic wave resonator of one Example of this invention. FIG. 3 is a schematic cross-sectional structure diagram along the XX'and YY' lines in FIG. 1. FIG. 3 is a schematic cross-sectional structure diagram along the XX'and YY' lines in FIG. 1. It is a top surface structure schematic diagram of the bulk acoustic wave resonator of another embodiment of this invention. It is a top surface structure schematic diagram of the bulk acoustic wave resonator of another embodiment of this invention. It is a top surface structure schematic diagram of the bulk acoustic wave resonator of another embodiment of this invention. It is a top surface structure schematic diagram of the bulk acoustic wave resonator of another embodiment of this invention. It is sectional drawing of the bulk acoustic wave resonator of another Example of this invention. It is sectional drawing of the bulk acoustic wave resonator of another Example of this invention. It is a flowchart of the manufacturing method of the bulk acoustic wave resonator of one Example of this invention. FIG. 3 is a schematic cross-sectional view taken along the line XX'in FIG. 1A in the method for manufacturing a bulk acoustic wave resonator according to an embodiment of the present invention. FIG. 3 is a schematic cross-sectional view taken along the line XX'in FIG. 1A in the method for manufacturing a bulk acoustic wave resonator according to an embodiment of the present invention. FIG. 3 is a schematic cross-sectional view taken along the line XX'in FIG. 1A in the method for manufacturing a bulk acoustic wave resonator according to an embodiment of the present invention. FIG. 3 is a schematic cross-sectional view taken along the line XX'in FIG. 1A in the method for manufacturing a bulk acoustic wave resonator according to an embodiment of the present invention. FIG. 3 is a schematic cross-sectional view taken along the line XX'in FIG. 1A in the method for manufacturing a bulk acoustic wave resonator according to an embodiment of the present invention. FIG. 3 is a schematic cross-sectional view taken along the line XX'in FIG. 1A in the method for manufacturing a bulk acoustic wave resonator according to an embodiment of the present invention. FIG. 3 is a schematic cross-sectional view taken along the line XX'in FIG. 1A in the method for manufacturing a bulk acoustic wave resonator according to an embodiment of the present invention. FIG. 3 is a schematic cross-sectional view taken along the line XX'in FIG. 1A in the method for manufacturing a bulk acoustic wave resonator according to an embodiment of the present invention. FIG. 3 is a schematic cross-sectional view taken along the line XX'in FIG. 1A in the method for manufacturing a bulk acoustic wave resonator according to another embodiment of the present invention.

Hereinafter, the technical solution of the present invention will be described in more detail with reference to the drawings and specific examples. Based on the following description, the effects and features of the present invention will become clearer. It should be noted that all the drawings use a very simplified format and inaccurate proportions, and are merely for the purpose of explaining the embodiments of the present invention easily, clearly and supplementarily. Similarly, if the method described herein comprises a series of steps, the order of these steps shown herein is not the only order in which these steps can be performed, and some of the steps are described. It may be omitted and / or some other steps not described herein may be added to the method. Further, the meaning of "displacement" of an object and an object in the present specification is that they do not overlap in the cavity region, that is, the projections on the bottom surface of both cavities do not overlap.

With reference to FIGS. 1A to 1C, FIG. 1A is a schematic top view of the bulk acoustic wave resonator according to an embodiment of the present invention, and FIG. 1B is a schematic cross-sectional structure along XX'in FIG. 1C is a schematic cross-sectional structure taken along the YY'line in FIG. 1A, and the bulk acoustic wave resonator of this embodiment includes a substrate, a bottom electrode layer 104, a piezoelectric resonance layer 1051, and a top electrode. Includes layer 108 and.

The substrate includes a base 100 and an etching protective layer 101 coated on the base 100. The base 100 may be any suitable base material known to those skilled in the art, for example, silicon (Si), germanium (Ge), silicon germanium (SiGe), silicon carbide (SiC), silicon germanium carbonization. (SiGeC), indium arsenide (InAs), gallium arsenide (GaAs), indium phosphate (InP), or other III / V compound semiconductors, at least one of the multilayer structures composed of these semiconductors, etc. It may be one, or silicon-on-insulator (SOI), laminated silicon-on-insulator (SSOI), laminated silicon-germanium-on-insulator (S-SiGeOI), laminated silicon-germanium-on. -It may be an insulator (SiGeOI) and a germanium-on-insulator (GeOI), or it may be a double-sided polished silicon wafer (Double Side Polished Wafers, DSP), or a ceramic base such as aluminum oxide, Sekiei. , Or it may be a glass base or the like. The material of the etching protection layer 101 may be any suitable dielectric material, and includes, but is limited to, at least one of materials such as silicon oxide, silicon nitride, silicon nitrogen oxide, and silicon carbide. I can't. The etching protection layer, on the other hand, improves the structural stability of the finally manufactured bulk acoustic wave resonator, enhances the separation between the bulk acoustic wave resonator and the base 100, and requires a resistance to the base 100. On the other hand, during the manufacturing process of the bulk acoustic wave resonator, other regions of the substrate are protected from etching, thereby improving the performance and reliability of the device.

A cavity 102 is formed between the bottom electrode layer 104 and the substrate. With reference to FIGS. 1A to 1C, in this embodiment, the cavity 102 may be formed by sequentially etching the thickness of a part of the etching protection layer 101 and the base 100 by an etching process, and the bottom portion may be formed. The whole has a groove structure recessed in the substrate. However, the technique of the present invention is not limited thereto, with reference to FIG. 2E, and in another embodiment of the present invention, the cavity 102 is followed by a sacrificial layer projecting from the surface of the etching protection layer 101. By the process of removing using the removing method, it may be formed above the top surface of the etching protection layer 101, and the whole becomes a cavity structure projecting from the surface of the etching protection layer 101. Further, in this embodiment, the shape of the bottom surface of the cavity 102 may be rectangular, but in another embodiment of the present invention, the shape of the bottom surface of the cavity 102 is further other than circular, elliptical, or rectangular. It may be a polygon (for example, a pentagon or a hexagon).

The piezoelectric resonance layer 1051 may be referred to as a piezoelectric resonance portion, which is located in the upper region of the cavity 102 (that is, located in the region of the cavity 102) and corresponds to the effective operating region of the bulk acoustic wave resonator. It is provided between the bottom electrode layer 104 and the top electrode layer 108. The bottom electrode layer 104 includes a bottom electrode bridge portion 1040, a bottom electrode protrusion 1041 and a bottom electrode resonance portion 1042 connected in order, and the top electrode layer 108 includes a top electrode bridge portion 1080 and a top electrode recess portion connected in order. The bottom electrode resonance portion 1042 and the top electrode resonance portion 1082 both include the top electrode resonance portion 1081 and the top electrode resonance portion 1082, and both overlap with the piezoelectric resonance layer 1051. The corresponding region of the cavity 102 constitutes the effective operating region 102A of the bulk acoustic wave resonator, the portion of the cavity 102 other than the effective operating region 102A is the invalid region 102B, and the piezoelectric resonance layer 1051 is effectively operated. Located in region 102A and separated from the membrane layer around the cavity 102, the effective working region of the bulk acoustic wave resonator can be completely restricted to the region of the cavity 102, and the piezoelectric by the membrane layer around the cavity 102. The influence on the longitudinal vibration generated in the resonance layer can be reduced, the parasitic parameter generated in the invalid region 102B can be reduced, and the performance of the device can be improved. The bottom electrode resonance portion 1042, the piezoelectric resonance layer 1051, and the top electrode resonance portion 1082 all have a flat structure having flat upper and lower surfaces, and the bottom electrode protrusion 1041 is a cavity 102B on the outer periphery of the effective operating region 102A. It is located above and is electrically connected to the bottom electrode resonance portion 1042 and protrudes in a direction away from the bottom surface of the cavity. As well as being positioned, it is electrically connected to the top electrode resonance portion 1082 and projects in a direction away from the bottom surface of the cavity 102. The entire bottom electrode protrusion 1041 is higher than the top surface of the bottom electrode resonance portion 1042, the entire top electrode recess 1081 is lower than the top surface of the top electrode resonance portion 1082, and the top electrode recess 1081 and the bottom electrode protrusion 1041 are formed. Both are located in the cavity region (that is, 102B) on the outer periphery of the piezoelectric resonance layer 1051. The bottom electrode protruding portion 1041 and the top electrode recessed portion 1081 may have a solid structure or a hollow structure, preferably a hollow structure, whereby the bottom electrode layer 104 and the top electrode layer 108 are formed. The film thickness can be made uniform, and the gravity of the solid bottom electrode protrusion 1041 prevents the bottom electrode resonance portion 1042 and the piezoelectric resonance layer 1051 from being separated from each other. The collapse deformation of the top electrode resonance portion 1082 and the piezoelectric resonance layer 1051 below the top electrode resonance portion 1081 and the bottom electrode resonance portion 1042 caused by the recessed portion 1081 is avoided, and the resonance coefficient is further improved. The bottom electrode resonance portion 1042 and the top electrode resonance portion 1082 are both polygonal (both the top surface and the bottom surface are polygonal), and the shapes of the bottom electrode resonance portion 1042 and the top electrode resonance portion 1082 are formed. May be similar (shown in FIGS. 2A-2B and 2D) or may be exactly the same (shown in FIGS. 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.

With reference to FIGS. 1A to 1C, in this embodiment, the bottom electrode layer 104, the piezoelectric resonance layer 1051 and the top electrode layer 108 form a “wrist” -like film layer structure, and the bottom electrode bridge portion 1040 resonates with the bottom electrode. Aligned with one corner of section 1042, top electrode bridge section 1080 aligned with one corner of top electrode resonance section 1082, bottom electrode bridge section 1040 and top electrode bridge section 1080 are two bands of "watch" The bottom electrode protruding portion 1041 is provided along the side of the bottom electrode resonance portion 1042, and is provided only in a region where the bottom electrode bridge portion 1040 and the bottom electrode resonance portion 1042 are aligned. The top electrode recessed portion 1081 is provided along the side of the top electrode resonance portion 1082, and is provided only in a region where the top electrode bridge portion 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 the dial of the "watch" and the two bands, and the bottom electrode resonance portion 1042 and the piezoelectric resonance layer 1051 in the effective region 102A. The laminated structure of the top electrode resonance portion 1082 corresponds to the dial of a wristwatch, in which the band portion is connected to the film layer on the substrate around the cavity, and the remaining portion is all through the cavity. Is separated from the film layer on the substrate around the cavity. That is, in this embodiment, both the bottom electrode protrusion 1041 and the top electrode recess 1081 extend around the peripheral direction of the piezoelectric resonance layer 1051, and the bottom electrode protrusion 1041 and the top electrode The recessed portion 1081 is surrounded by only a part of the side of the piezoelectric resonance layer 1051 along the peripheral direction of the piezoelectric resonance layer 1051, and refers to the plane on which the piezoelectric resonance layer 1051 is located. The bottom electrode protrusions 1041 are located on both sides of the piezoelectric resonance layer 1051 and are completely opposed to each other, thereby realizing a predetermined lateral wave blocking effect and at the top electrode bridge portion 1080 and the bottom electrode bridge portion 1040. It contributes to the reduction of the area of the uncovered invalid region 102B, further contributes to the reduction of the size of the device, and also contributes to the reduction of the area of the top electrode bridge portion 1080 and the bottom electrode bridge portion 1040, and further increases the parasitic parameters. Reduce and improve the electrical performance of the device. The bottom electrode bridge portion 1040 is electrically connected to the back side of the bottom electrode protruding portion 1041 with the bottom electrode resonance portion 1042, and the bottom electrode protruding portion 1041 is formed from above the bottom electrode protruding portion 1041. After passing above the cavity (that is, 102B) floating on the outside, it extends to above a part of the etching protection layer 101 on the outer periphery of the cavity 102, and the top electrode bridge portion 1080 extends to the top electrode. A cavity (that is, 102B) that is electrically connected to the back side of the recessed portion 1081 with the top electrode resonance portion 1082 and floats from above the top electrode recessed portion 1081 to the outside of the top electrode recessed portion 1081. After passing through the upper part, it extends to the upper part of a part of the etching protection layer 101 on the outer periphery of the cavity 102, and the bottom electrode bridge portion 1040 and the top electrode bridge portion 1080 face each other of the cavity 102. It extends to the upper part of the substrate outside the side, and at this time, the bottom electrode bridge portion 1040 and the top electrode bridge portion 1080 are displaced from each other in the cavity 102 region (that is, they do not overlap). As a result, the parasitic parameters can be reduced, problems such as leakage and short circuit due to contact between the bottom electrode bridge portion and the top electrode bridge portion can be avoided, and the performance of the device can be improved. The bottom electrode bridge portion 1040 is used to transfer a signal corresponding to the bottom electrode resonance portion 1042 via the bottom electrode protrusion 1041 by connecting the corresponding signal line, and the top electrode bridge portion 1080 is used. , By connecting the corresponding signal line, it is used to transfer the signal corresponding to the top electrode resonance part 1082 through the top electrode recess 1081, so that the bulk acoustic wave resonator can operate normally. Specifically, by applying a time-varying voltage to the bottom electrode resonance portion 1042 and the top electrode resonance portion 1082 via the bottom electrode bridge portion 1040 and the top electrode bridge portion 1080, respectively, the longitudinal extension mode or the vertical extension mode or , Exciting the "piston" mode, the piezoelectric resonance layer 1051 converts the energy in the form of electrical energy into longitudinal waves, and in this process a parasitic transverse wave is generated, and the bottom electrode protrusion 1041 and the top electrode recess 1081 are these. The transverse waves can be blocked from propagating to the membrane layer at the outer periphery of the cavity and restricted within the region of the cavity 102, thereby avoiding energy loss due to the transverse waves and improving the quality coefficient.

Preferably, the line widths of the top electrode recess 1081 and the bottom electrode protrusion 1041 are the minimum line widths allowed for the corresponding process, respectively, and the horizontal distance between the bottom electrode protrusion 1041 and the piezoelectric resonance layer 1051. The horizontal distance between the top electrode recess 1081 and the piezoelectric resonance layer 1051 is the minimum distance allowed for the corresponding process, which causes the top electrode recess 1081 and the bottom electrode protrusion 1041 to have a predetermined transverse wave. It can realize the blocking effect and contribute to the reduction of the device area.

Further, the side wall of the top electrode recessed portion 1081 is a side wall inclined with respect to the top surface of the piezoelectric resonance layer, and as shown in FIG. 1B, the XX'line of FIG. 1A of the top electrode recessed portion 1081. The cross section along is a trapezoidal shape or a shape similar to a trapezoidal shape, and the angles β1 and β2 between the two side walls of the top electrode recess 1081 and the top surface of the piezoelectric resonance layer 1051 are both 45 degrees or less. Therefore, since the side wall of the top electrode recess 1081 is too vertical, the top electrode recess 1081 is cut off, and the effect of transferring the signal to the top electrode resonance portion 1082 is prevented from being affected. Further, the thickness uniformity of the entire top electrode layer 108 can be further improved, and the side wall of the bottom electrode protrusion 1041 is a side wall inclined with respect to the bottom surface of the piezoelectric resonance layer, and is shown in FIG. 1B. As described above, the cross section of the bottom electrode protrusion 1041 along the XX'line in FIG. 1A has a trapezoidal shape or a shape similar to the trapezoidal shape, and the two side walls of the bottom electrode protrusion 1041 and the piezoelectric resonance layer 1051. The angles α1 and α2 with the bottom surface of the bottom electrode are both 45 degrees or less, which causes the side wall of the bottom electrode protrusion 1041 to be too vertical, so that the bottom electrode layer 104 is cut off and the bottom electrode resonance portion is further formed. It is possible to avoid affecting the effect of transferring the signal to 1042, and to further improve the thickness uniformity of the bottom electrode layer 104.

In one preferred embodiment of the present invention, the bottom electrode resonance portion 1042, the bottom electrode protrusion 1041 and the bottom electrode bridge portion 1040 are formed by the same film layer manufacturing process (that is, the same film layer manufacturing process), and the top is formed. The electrode resonance portion 1082, the top electrode recess 1081 and the top electrode bridge portion 1080 are formed by the same film layer manufacturing process (that is, the same film layer manufacturing process), that is, the bottom electrode resonance portion 1042, the bottom electrode protrusion 1041. And the bottom electrode bridge portion 1040 is a film layer integrally manufactured, and the top electrode resonance portion 1082, the top electrode recess 1081 and the top electrode bridge portion 1080 are integrally manufactured film layers. The film layer material for manufacturing the bottom electrode resonance portion 1042, the bottom electrode protrusion 1041 and the bottom electrode bridge portion 1040 by simplifying the process and reducing the cost, and the top electrode resonance portion 1082, the top electrode recessed portion 1081 and the top. As the film layer material for manufacturing the electrode bridge portion 1080, any appropriate conductive material or semiconductor material well known in the art may be used, and the conductive material is a metal having conductivity. The material may be, for example, aluminum (Al), copper (Cu), platinum (Pt), gold (Au), molybdenum (Mo), tungsten (W), iridium (Ir), osmium (Os), renium. (Re), one or more of palladium (Pd), rhodium (Rh) and ruthenium (Ru), and the semiconductor material is, for example, Si, Ge, SiGe, SiC, SiGeC and the like. In another embodiment of the present invention, the bottom electrode resonance portion 1042, the bottom electrode protrusion 1041 and the bottom electrode bridge portion 1040 may be formed by different film layer manufacturing processes, on the premise that the process cost and the process technique allow. Often, the top electrode resonance portion 1082, the top electrode recessed portion 1081 and the top electrode bridge portion 1080 may be formed by different film layer manufacturing processes.

With reference to FIGS. 2A to 2D, in order to further improve the lateral wave blocking effect, the bottom electrode protrusion 1041 extends to more continuous sides of the bottom electrode resonance portion 1042, and the top electrode recess 1081 is the top. If the electrode resonance portion 1082 extends to more continuous sides and the bottom electrode protrusion 1041 and the top electrode recess 1081 overlap, refer to FIG. 2F and have a gap H between them. As a result, the top electrode layer 108 and the bottom electrode layer 104 do not come into electrical contact with each other, thus avoiding the short-circuit problem. For example, with reference to FIG. 2A, the projection of the bottom electrode protrusion 1041 and the top electrode recess 1081 on the bottom surface of the cavity 102 may be just connected or nearly connected, ie, the bottom electrode protrusion 1041. And the projection of the top electrode recess 1081 on the bottom surface of the cavity 102 may form a completely closed ring or a substantially closed ring, whereby the bottom electrode protrusion 1041 and the top electrode recess 1081 may be formed. By fitting, it is possible to block lateral waves from all the periphery of the piezoelectric resonance layer 1051, and in this case, the projected size of the bottom electrode protruding portion 1041 and the top electrode recessed portion 1081 on the bottom surface of the cavity 102. In addition, the ring formed by combining the two may be uniformly divided (at this time, the bottom electrode protruding portion 1041 and the top electrode recessed portion 1081 are located on both sides of the piezoelectric resonance layer 1051 and all portions thereof. However, it is not necessary to divide them uniformly (at this time, the bottom electrode protrusion 1041 and the top electrode recess 1081 are located on both sides of the piezoelectric resonance layer 1051 and only a part thereof. opposite). Further, for example, referring to FIG. 2B, the piezoelectric resonance layer 1051, the top electrode resonance portion 1082, and the bottom electrode resonance portion 1042 all have a pentagonal planar structure, the area of the piezoelectric resonance layer 1051 is the smallest, and the top electrode resonance. The portion 1082 is larger than that, and the area of the bottom electrode resonance portion 1042 is the largest. The bottom electrode protrusion 1041 is provided along each side of the bottom electrode resonance portion 1042 and is connected to each side. A part or all projections on the bottom surface of the cavity 102 at the boundary connected from the top electrode bridge portion 1080 of the top electrode recess 1081 are exposed from the projections on the bottom surface of the cavity 102 of the bottom electrode protrusion 1041. The top electrode recessed portion 1081 is provided along each side of the top electrode resonance portion 1082 and is connected to each side, and is connected to the bottom electrode bridge portion 1040 of the bottom electrode protruding portion 1041. Some or all projections on the bottom surface of the boundary cavity 102 are exposed from the projections on the bottom surface of the cavity 102 of the top electrode recess 1081, thereby forming the bottom electrode protrusion 1041 and the top electrode bridge 1080. The top electrode recessed portion 1081 and the bottom electrode bridge portion 1040 do not overlap with each other, and the parasitic parameters can be further reduced. Further, the bottom electrode protruding portion 1041 and the top electrode recessed portion 1081 are mutually compatible with each other. It may be slightly displaced (the overlapping portions do not touch), or it may be completely displaced, that is, at this time, the bottom electrode protruding portion 1041 and the top electrode recessed portion 1081 may be displaced in the direction perpendicular to the piezoelectric resonance layer 1051. All parts face each other in the peripheral direction of the piezoelectric resonance layer 1051, although some parts are aligned vertically but do not touch or are completely displaced, whereby the projection structure at the bottom surface of the cavity. In, the bottom electrode protruding portion 1041 can partially surround the top electrode recessed portion 1081, and in this way, the bottom electrode protruding portion 1041 and the top electrode recessed portion 1081 are fitted to each other, whereby the piezoelectric resonance layer is formed. Lateral wave blocking can be performed on all the periphery of 1051, and the requirement for alignment between the bottom electrode protruding portion 1041 and the top electrode recessed portion 1081 can be reduced, which contributes to the reduction of manufacturing difficulty of the process. Further, for example, referring to FIG. 2C, the piezoelectric resonance layer 1051, the top electrode resonance portion 1082, and the bottom electrode resonance portion 1042 all have a pentagonal planar structure, the area of the piezoelectric resonance layer 1051 is the smallest, and the top electrode resonance. The area, shape, etc. of the portion 1082 and the bottom electrode resonance portion 1042 are the same or substantially the same, and the bottom electrode protrusion 1041 surrounds the entire circumference of the bottom electrode resonance portion 1042 and is a top electrode recessed portion. The 1081 surrounds the entire circumference of the top electrode resonance portion 1082, the projections of the bottom electrode protrusion 1041 and the top electrode recess 1081 on the bottom surface of the cavity 102 overlap, and the cavity of the top electrode resonance portion 1082 and the bottom electrode resonance portion 1042. The projections on the bottom surface of 102 overlap, which causes the different heights of the piezoelectric resonance layer 1051 due to the fact that the bottom electrode protrusions 1041 and the top electrode recesses 1081 located at different heights both exhibit a closed annular shape. It is possible to block horizontal waves of height. That is, when the bottom electrode protruding 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 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 respectively. Partially surrounds the periphery of the piezoelectric resonance layer 1051 along the peripheral direction of the piezoelectric resonance layer 1051 (shown in FIGS. 2A to 2B). The bottom electrode protrusion 1041 and the top electrode recess 1081 each partially face each other or surround the entire circumference of the piezoelectric resonance layer 1051 along the peripheral direction of the piezoelectric resonance layer 1051 (shown in FIG. 2C). At this time, all the portions of both the top electrode recessed portion 1081 and the bottom electrode protruding portion 1041 face each other.

With reference to FIGS. 2A-2D, in these embodiments of the present invention, the bottom electrode bridge portion 1040 is at least one side of the bottom electrode protrusion 1041 facing away from the bottom electrode resonance portion 1042, or at least. After passing over the cavity (that is, 102B) electrically connected to one corner and floating outside the bottom electrode protrusion 1041 from the corresponding side of the bottom electrode protrusion 1041, the cavity 102 The top electrode bridge portion 1080 extends above a part of the etching protection layer 101 on the outer periphery, and the top electrode bridge portion 1080 has at least one side or at least one side facing the top electrode resonance portion 1082 of the top electrode recessed portion 1081. A part of the outer periphery of the cavity 102 after being electrically connected to one corner and passing from the top electrode recess 1081 above the cavity (ie, 102B) floating outside the top electrode recess 1081. Extending above the etching protection layer 101, the projections of the top electrode bridge portion 1080 and the bottom electrode bridge portion 1040 on the bottom surface of the cavity 102 may be just connected or separated from each other. Thereby, the top electrode bridge portion 1080 and the bottom electrode bridge portion 1040 may be displaced from each other in the region of the cavity 102 without overlapping. For example, as shown in FIGS. 1A and 2A to 2C, the bottom electrode bridge portion 1040 extends above a part of the substrate on the outer periphery of only one side of the cavity 102, and the top electrode bridge. The portion 1080 extends to the upper part of a part of the substrate on the outer periphery of only one side of the cavity 102, and is formed on the bottom surface of the cavity 102 of the top electrode bridge portion 1080 and the bottom electrode bridge portion 1040. Projections are separated from each other, thereby avoiding problems such as introduction of parasitic parameters and possible leaks and short circuits when the top electrode bridge portion 1080 and the bottom electrode bridge portion 1040 overlap. However, preferably, with reference to FIG. 2D, when the bottom electrode protrusion 1041 is provided along a plurality of continuous sides of the bottom electrode resonance portion 1042, the bottom electrode bridge portion 1040 is the bottom electrode protrusion 1041. The bottom electrode bridge portion 1040 is provided along all the sides facing the bottom electrode resonance portion 1042 and continuously extends to the substrate at the outer periphery of the cavity 102, whereby the bottom electrode bridge portion 1040 is provided in the cavity 102. It can extend above a portion of the substrate in more directions on the outer circumference of 102, i.e., the bottom electrode bridge portion 1040 is above the portion of the cavity in which it is located. In, the cavity 102 is completely covered, whereby the laying of the large-area bottom electrode bridge portion 1040 increases the bearing capacity of the effective working region 102A for the membrane layer and prevents the cavity 102 from collapsing. More preferably, when the bottom electrode bridge portion 1040 extends above the portion of the substrate in more directions on the outer periphery of the cavity 102, the top electrode bridge portion 1080 extends to the outer periphery of the cavity 102. When the upper surface shape of the cavity 102 is rectangular, for example, the top electrode bridge portion 1080 extends to the upper side of a part of the substrate in only one direction in the above, and the outer periphery of only one side of the cavity 102. The bottom electrode bridge portion 1040 extends to the upper part of the substrate in the above, and extends to the other three sides of the cavity 102. At this time, the top electrode bridge portion 1080 and the bottom electrode bridge portion 1040 extend. Projections on the bottom surface of the cavity 102 with are just connected or separated from each other, i.e., where the bottom electrode bridge portion 1040 is above a portion of the cavity in which it is located. , Completely covers the cavity 102 and does not overlap with the top electrode bridge portion 1080 in the width direction of the top electrode bridge portion 1080. As a result, if the top electrode bridge portion is provided in a large area, it overlaps with the structure such as the bottom electrode bridge portion in the vertical direction, so that it is possible to avoid introducing too many parasitic parameters and further improve the electrical performance and reliability of the device. Can be improved.

In each embodiment of the present invention, when the upper surface shape of the cavity 102 is polygonal, at least one side of the cavity is exposed from each of the bottom electrode bridge portion 1040 and the top electrode bridge portion 1080, whereby at least one side of the cavity is exposed. At least one end of each of the bottom electrode resonance portion 1042 to which the bottom electrode protrusion 1041 is connected and the top electrode resonance portion 1082 to which the top electrode recess 1081 is connected is completely floating. It contributes to the reduction of the area, further reduces the parasitic parameters such as the parasitic capacitor generated in the invalid region 102B, and improves the performance of the device. Preferably, the bottom electrode protrusion 1041 is displaced from at least the top electrode bridge portion 1080 above the cavity 102 (ie, they do not overlap in the cavity region), and the top electrode recess 1081 is the cavity. Above the 102, at least misaligned with the bottom electrode bridge portion 1040 (ie, they do not overlap in the cavity region), and the projection of the top electrode recess 1081 and the bottom electrode protrusion 1041 on the bottom surface of the cavity 102. Are just connected, or offset from each other, or only partially overlap. As a result, the parasitic parameters such as the parasitic capacitor generated in the invalid region 102B are further reduced, and the performance of the device is improved.

In order to realize the optimum lateral wave blocking effect and contribute to the production of a device having a small size, it is preferable that the top electrode recess 1081 and the bottom electrode protrusion 1041 are closer to the effective operating region 102A. The smaller the line widths of 1081 and the bottom electrode protrusion 1041, the more preferable, and preferably, the line widths of the top electrode recess 1081 and the bottom electrode protrusion 1041 are the minimum line widths allowed for the corresponding process, respectively. The horizontal distance between the electrode recess 1081 and the bottom electrode protrusion 1041 and the effective working region 102A (ie, the piezoelectric resonance layer 1051) is the minimum distance allowed for the corresponding process, respectively.

In each of the above embodiments, the top electrode resonance portion 1082 and the bottom electrode resonance portion 1042 have similar or the same shape and have the same area, or the area of the bottom electrode resonance portion 1042 is the top electrode. Although it is larger than the area of the resonance portion 1082, the technical solution of the present invention is not limited to this. In another embodiment of the present invention, the shapes of the top electrode resonance portion 1082 and the bottom electrode resonance portion 1042 do not have to be similar, but the top electrode recessed portion 1081 and the bottom electrode protruding portion 1041 have a piezoelectric resonance in shape. It is preferable that it matches the shape of the layer 1051 and can extend along at least one side of the piezoelectric resonance layer 1051. In addition, studies have found that most of the parasitic shear waves in bulk acoustic wave resonators are transmitted through the connection structure between the membrane layer on the effective working area 102A and the substrate at the outer periphery of the cavity, and therefore. In each embodiment of the present invention, the area (that is, line width) of the top electrode bridge portion 1080 is minimized, and the bottom electrode bridge portion 1040 is provided on the premise that the film layer of the effective working region 102A can be effectively supported. The area (ie, line width) can be controlled as much as possible to the minimum.

One embodiment of the present invention further provides a filter comprising at least one bulk acoustic wave resonator according to any of the above embodiments of the present invention.

An embodiment of the present invention further provides a radio frequency communication system comprising at least one filter according to the embodiment of the present invention.

With reference to FIG. 3, an embodiment of the present invention is a method for manufacturing a bulk acoustic wave resonator (for example, the bulk acoustic wave resonator shown in FIGS. 1A to 2D) of the present invention.
Step S1 to provide a substrate and form a first sacrificial layer with sacrificial protrusions on a portion of the substrate.
In step S2, the bottom electrode layer is formed on the first sacrificial layer, and the portion of the bottom electrode layer covered with the surface of the sacrificial protrusion forms the bottom electrode protrusion.
Step S3 in which the piezoelectric resonance layer is formed on the bottom electrode layer and the bottom electrode protrusion is exposed from the piezoelectric resonance layer.
Step S4, in which the second sacrificial layer having the first groove is formed in the region exposed from the periphery of the piezoelectric resonance layer,
The top electrode layer is formed on the piezoelectric resonance layer and a part of the second sacrificial layer around the piezoelectric resonance layer, and the portion of the top electrode layer covered with the first groove forms the top electrode recess. Step S5 and
A step S6 of removing the second sacrificial layer and the first sacrificial layer having the sacrificial protrusion and forming a cavity at the position of the second sacrificial layer and the first sacrificial layer having the sacrificial protrusion is included. , Further provides a manufacturing method.

With reference to FIGS. 1A and 1B and FIGS. 4A-4B, in step S1 of this embodiment, the first sacrificial layer is partially used as a substrate by a process of etching a substrate to form a groove and filling the groove with a material. The concrete realization process formed above includes:

First, with reference to FIGS. 1A and 4A, a substrate is provided, specifically, a base 100 is provided, and the base 100 is coated with an etching protection layer 101. The etching protection layer 101 is provided by an arbitrary appropriate process method such as a heat treatment method such as thermal oxidation, thermal nitriding, or thermal oxynitriding, or a deposition method such as chemical vapor deposition, physical vapor deposition, or atomic layer deposition. , May be formed on the base 100. Further, the etching thickness of the protective layer 101 may be rationally set according to the needs of the actual device process, and is not specifically limited here.

Subsequently, with reference to FIGS. 1A, 1B and 4A, at least one second groove 102'is formed by etching the substrate by a photo-etching and etching process. The etching process may be a wet etching process or a dry etching process, and it is preferable to use a dry etching process. The dry etching includes reactive ion etching (RIE), ion beam etching, plasma etching, or laser cutting. Including, but not limited to these. The depth and shape of the second groove 102'are all determined by the depth and shape of the cavity required for the bulk acoustic wave resonator to be manufactured, and the cross-sectional shape of the second groove 102'is rectangular. Yes, in other embodiments of the invention, the cross section of the second groove 102'is further any other suitable polygon, such as a circular, elliptical or non-rectangular polygon (pentagon, hexagon, etc.). It may have a different shape.

Next, with reference to FIGS. 1A, 1B and 4B, the first sacrificial layer 103 may be filled in the second groove 102'by a process such as vapor deposition, thermal oxidation, spin coating or epitaxial growth. For the first sacrificial layer 103, a semiconductor material, a dielectric material, a photoresist material, or the like different from the base 100 and the etching protection layer 101 may be selected. For example, when the base 100 is a Si base, the first sacrificial layer 103 may be selected. The sacrificial layer 103 may be Ge, in which case the first sacrificial layer 103 formed is further coated with an etching protective layer 101 on the outer periphery of the groove, or the top surface of the groove is grooved. It may be higher than the top surface of the surrounding etching protection layer 101, and then the top of the first sacrificial layer 103 is flattened to the top surface of the etching protection layer 101 by a chemical mechanical flattening (CMP) process. By doing so, the first sacrificial layer 103 is positioned only 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 it. This provides a flat process surface for subsequent processes.

Subsequently, the first sacrificial layer 103 is coated with a sacrificial material layer (not shown) by an appropriate process such as a coating process or a vapor deposition process, and the thickness of the sacrificial material layer is subsequently formed. The height of the protrusion of the bottom electrode is determined, and the material of the sacrificial material layer is amorphous carbon, a photoresist, a dielectric material (for example, silicon nitride, silicon carbide, a porous material, etc.), or a semiconductor material (for example). For example, it may be at least one selected from (polycrystalline silicon, amorphous silicon, germanium) and the like, and then the sacrificial material layer is patterned by a lithography process or a combined photoetching and etching process. The sacrificial protrusion 103'is formed, and the line width, size, shape, and position of the bottom electrode protrusion to be formed thereafter are determined by the line width, size, shape, and position of the sacrificial protrusion 103'. In this embodiment, the vertical cross section of the sacrificial protrusion 103'along the XX'of FIG. 2A is a trapezoid that widens from top to bottom, with the side wall of the sacrificial protrusion 103'and the top surface of the first sacrificial layer 103. The angles φ1 and φ2 between are less than 45 degrees, which contributes to the subsequent deposition of the bottom electrode material layer and the thickness of the bottom electrode layer formed thereafter is uniform within the second groove 102'region. Further improve sex. In another embodiment of the present invention, the cross-sectional shape of the sacrificial protrusion 103'may be a spherical crown that widens from top to bottom, that is, the vertical cross-sections along the XX'line of FIG. 1A are all reversed. It is U-shaped. The horizontal distance between the sacrificial protrusion 103'and the effective working region 102A is preferably the minimum distance allowed for the etching alignment process of the sacrificial protrusion 103', and the line width of the sacrificial protrusion 103'is. The minimum line width allowed for the corresponding process.

In another embodiment of the invention, the sacrificial protrusion 103'and the first sacrificial layer 103 may be formed in the same process, eg, first on the second groove 102'and the etching protection layer 101 to a thickness. Covers the first sacrificial layer 103, which is greater than or equal to the sum of the depth of the second groove 102'and the thickness of the sacrificial protrusion 103', and then the first sacrificial layer 10 is patterned by an etching process. A first sacrificial layer 103 is formed to be filled only in the second groove 102', a part of the first sacrificial layer 103 has a sacrificial protrusion 103', and the bottom surface of the sacrificial protrusion 103'is etching protection. It may be flush with the top surface of the layer 101, or the top surface of the remaining first sacrificial layer 103 may be flush with the top surface of the etching protection layer 101.

With reference to FIGS. 1A, 1B and 4D, in step S2, first, an appropriate method is selected according to the material of the bottom electrode formed in advance, and the etching protection layer 101, the first sacrificial layer 103 and the sacrificial protrusion are selected. The surface of 103'may be coated with a bottom electrode material layer (not shown), and the bottom electrode material layer is formed by, for example, a physical vapor phase deposition such as magnetron sputtering or vapor deposition, or a chemical vapor phase deposition method. Next, a photoresist layer (not shown) in which a bottom electrode pattern is defined is formed on the bottom electrode material layer by a lithography process, and the bottom electrode material layer is etched using the photoresist layer as a mask to obtain a bottom. The electrode layer (ie, the remaining bottom electrode material layer) 104 is formed, after which the photoresist layer is removed. As the bottom electrode material layer, any appropriate conductive material or semiconductor material known in the art can be used, and the conductive material may be a metal material having conductivity, for example, aluminum ( Al), copper (Cu), platinum (Pt), gold (Au), molybdenum (Mo), tungsten (W), iridium (Ir), osmium (Os), ruthenium (Re), palladium (Pd), rhodium ( It is one or more of Rh) and ruthenium (Ru), and the semiconductor material is, for example, Si, Ge, SiGe, SiC, SiGeC and the like. In this embodiment, the bottom electrode layer (remaining bottom electrode material layer) 104 is the bottom electrode resonance portion 1042 covered with the effective working region 102A formed thereafter, and the bottom electrode protrusion covered with the sacrificial protrusion 103'. It extends from one side of the portion 1041 and the bottom electrode protrusion 1041 to a part of the etching protection layer 101 outside the second groove 102'via the surface of the first sacrificial layer 103. The bottom electrode bridge portion 1040 and the bottom electrode resonance portion 1042 and the bottom electrode protrusion 1041 are both separated from the bottom electrode outer peripheral portion 1043, and the bottom electrode outer peripheral portion 1043 is a bulk to be formed in the region. As one metal contact of the acoustic wave resonator, it may be connected to the side opposite to the bottom electrode resonance portion 1042 of the bottom electrode protrusion 1041, or a part of the bottom electrode bridge portion of the adjacent bulk acoustic wave resonator. As a result, it may be separated from the bottom electrode bridge portion 1040, and in another embodiment of the present invention, the outer peripheral portion 1043 of the bottom electrode may be omitted. The top surface shape of the bottom electrode resonance portion 1042 may be pentagonal, or in another embodiment of the present invention, it may be a quadrangular shape or a hexagonal shape. Provided between the bottom electrode resonance portion 1042 and the bottom electrode protrusion 1041 is provided along at least one side of the bottom electrode resonance portion 1042 and connected to the corresponding side of the bottom electrode resonance portion 1042. The bottom electrode bridge portion 1040 is electrically connected to at least one side facing the bottom electrode resonance portion 1042 of the bottom electrode protruding portion 1041 or at least one corner, and the bottom electrode protruding portion is formed. A part of the etching protection layer 101 on the outer periphery of the second groove 102'after passing from the corresponding side of 1041 through the top surface of the first sacrificial layer 103 coated on the outside of the bottom electrode protrusion 1041. The bottom electrode protruding portion 1041 is provided along the side of the bottom electrode resonance portion 1042, and the bottom electrode bridge portion 1040 and the bottom electrode resonance portion 1042 are provided. For example, the bottom electrode protrusion 1041 may surround the entire circumference of the bottom electrode resonance portion 1042 to form a closed ring structure (see FIG. 2C). It may be provided along only one side of the bottom electrode resonance portion 1042, or may have an open ring structure provided along two or more continuous sides of the bottom electrode resonance portion 1042 (Fig.). See 2A-2B and 2D). The shape, line width, horizontal distance between the bottom electrode protrusion 1041 and the effective working area 102A are all determined by the forming process of the sacrificial protrusion 103'. Preferably, as shown in FIG. 2D, the bottom electrode bridge portion 1040 completely covers the cavity 102 above a portion of the cavity in which it is located and in the width direction of the top electrode bridge portion 1080. By not overlapping with the apex electrode bridge portion 1080, the bearing capacity for the subsequent film layer is improved, and since it overlaps with the apex electrode bridge portion 1080, unnecessary parasitic parameters are avoided as much as possible, for example. When the upper surface shape of the second groove 102'is rectangular, the bottom electrode bridge portion 1040 extends to the three sides of the rectangle. The bottom electrode resonance portion 1042 may be used as an input electrode or an output electrode for receiving or providing an electric signal such as a radio frequency (RF) signal. In this embodiment, the bottom electrode protruding portion 1041, the bottom electrode resonance portion 1042, and the bottom electrode bridge portion 1040 have substantially the same thickness.

With reference to FIGS. 1A, 1B and 4E, in step S3, the piezoelectric material layer 105 is first subjected to any suitable method known to those skilled in the art, such as chemical vapor phase deposition, physical vapor phase deposition or atomic layer deposition. It may be deposited and formed. Next, a photoresist layer (not shown) in which a piezoelectric thin film pattern is defined is formed on the piezoelectric material layer 105 by a lithography process, and the photoresist layer is used as a mask to form the piezoelectric material layer 105. The piezoelectric resonance layer 1051 is formed by etching, and then the photoresist layer is removed. The material of the piezoelectric material layer 105 is aluminum nitride (AlN), zinc oxide (ZnO), lead zirconate titanate (PZT), lithium niobate (LiNbO ₃ ), sekiei (Quartz), potassium niobate (KNbO ₃ ). Alternatively, a piezoelectric material having a wurtzite type crystal structure such as lithium tantalate (LiTaO ₃ ) and a combination thereof may be used. The piezoelectric material layer 105 may further contain a rare earth metal as well as aluminum nitride (AlN), for example, at least one of scandium (Sc), erbium (Er), yttrium (Y) and lantern (La). It is a seed. Further, when the piezoelectric material layer 105 contains aluminum nitride (AlN), it further contains a transition metal (for example, at least one of zirconium (Zr), titanium (Ti), manganese (Mn) and hafnium (Hf)). May include. The remaining piezoelectric material layer 105 after patterning includes a piezoelectric resonance layer 1051 and a piezoelectric outer peripheral portion 1050 that are separated from each other, and the piezoelectric resonance layer 1051 is located on the bottom electrode resonance portion 1042 and has a bottom electrode protrusion 1041. May be exposed and completely or partially covered by the bottom electrode resonant portion 1042. The shape of the piezoelectric resonance layer 1051 may be the same as or different from the shape of the bottom electrode resonance portion 1042, and the shape of the upper surface thereof may be a pentagon, a quadrangle, a hexagon, a heptagon, or It may be another polygon such as an octagon. By forming a gap between the piezoelectric outer peripheral portion 1050 and the piezoelectric resonance layer 1051, the first sacrificial layer 103 around the bottom electrode protruding portion 1041 and the bottom electrode resonance portion 1042 is exposed, and the gap formed causes the gap. It limits the formation region of the subsequent second sacrificial layer and also provides a flat process surface for the formation of the subsequent second sacrificial protrusion, the piezoelectric outer periphery 1050 being the outer periphery of the apical electrode formed thereafter. It is possible to realize the separation between the portion and the outer peripheral portion 1043 of the bottom electrode formed before this, and it is possible to provide a flat process surface for the formation of the subsequent second sacrificial layer and top electrode layer. ..

With reference to FIGS. 1A, 1B and 4F, in step S4, first, the piezoelectric outer peripheral portion 1050, the piezoelectric resonance layer 1051, and the piezoelectric outer peripheral portion 1050 and the piezoelectric resonance layer are subjected to an appropriate process such as a coating process or a gas phase deposition process. The gap between the sacrificial layer 106 may be covered with the second sacrificial layer 106, and the second sacrificial layer 106 can fully fill the gap between the piezoelectric outer peripheral portion 1050 and the piezoelectric resonance layer 1051. The material of the second sacrificial layer 106 is an amorphous carbon, a photoresist, a dielectric material (for example, silicon nitride, silicon acid carbide, a porous material, etc.), or a semiconductor material (for example, polycrystalline silicon, amorphous silicon, germanium). ) And the like, and it is preferable that the material of the second sacrificial layer 106 is different from that of the first sacrificial layer 103, and in the subsequent etching process for forming the first groove 107. The top surface of the first sacrificial layer 103 can be used as an etching stop point, and the depth of the first groove 107 formed thereafter can be controlled, and then the second sacrificial layer 106 is formed by a CMP process. On the other hand, by flattening the top, the second sacrificial layer 106 is filled only in the gap between the piezoelectric outer peripheral portion 1050 and the piezoelectric resonance layer 1051, and the piezoelectric outer peripheral portion 1050, the piezoelectric resonance layer 1051 and the second sacrifice are made. The layer 106 constitutes a flat top surface. In another embodiment of the present invention, the piezoelectric outer peripheral portion 1050 and the piezoelectric resonance layer 1051 are provided by removing the piezoelectric outer peripheral portion 1050 and the second sacrificial layer 106 on the upper surface of the piezoelectric resonance layer 1051 by an etching back process. It may be filled only in the gap between them. Next, the second sacrificial layer 106 is patterned by a lithography process or a combination process of photoetching and etching to form a first groove 107, depending on the shape, size, position, etc. of the first groove 107. , The shape, size, position, etc. of the recessed portion of the top electrode formed after this are determined. Preferably, the side wall of the first groove 107 is an inclined side wall with respect to the plane on which the piezoelectric resonance layer 1051 is located, and is an angle between the side wall of the first groove 107 and the top surface of the piezoelectric resonance layer 1051. Both θ1 and θ2 are 45 degrees or less, which contributes to coating the material on the top electrode recess 1081 after that, avoids the occurrence of cutting, and contributes to improving the thickness uniformity. More preferably, the line width of the first groove 107 is the minimum line width allowed for the corresponding process and the horizontal distance between the first groove 107 and the piezoelectric resonant layer 1051 is the corresponding process. This is the minimum allowable distance, which provides a favorable shear wave blocking effect and contributes to reducing the size of the device. In another embodiment of the invention, the first groove 107 and the sacrificial protrusion 103'are formed after etching the second sacrificial layer 106 when the first groove 107 and the sacrificial protrusion 103'do not overlap at all in the vertical direction. A certain amount of overetching may be present so that the bottom surface is stopped at the top surface of the first sacrificial layer 103 or to a predetermined thickness, whereby the top electrode recess 1081 formed thereafter is bottomed out. The side portion of the piezoelectric resonance layer 1051 not surrounded by the electrode recess 1041 is supplemented, and the combination of the top electrode recess 1081 and the bottom electrode recess 1041 can surround the entire circumference of the piezoelectric resonance layer 1051. In another embodiment of the invention, the cross-sectional shape of the first groove 107 may be further narrowed from top to bottom, that is, the vertical cross-section along the XX'line of FIG. 1A is U. It is in the shape of a letter.

In another embodiment of the present invention, the second sacrificial layer 106 is made of a different material and is laminated from bottom to top with a first sub-sacrificial layer (not shown) and a second sub-sacrificial layer (Fig.). By providing the first sub-sacrificial layer and the second sub-sacrificial layer, the stop point of etching can be accurately controlled when the first groove is subsequently etched and formed. Further, the recess depth of the top electrode recess 1081 formed after this can be accurately controlled, and as can be seen from the above, the thickness of the second sub-sacrificial layer determines the top electrode formed after this. The recess depth of the recess 1081 is determined. In the following steps, a second sacrificial layer 106 having a first sub-sacrificial layer, a second sub-sacrificial layer and a first groove 107 may be formed. First, a material selected as the first sub-sacrificial layer by filling the gap between the piezoelectric resonance layer 1051 and the piezoelectric outer peripheral portion 1050 by a vapor phase deposition or an epitaxial growth process. Can be converted to other materials after being treated by some process, in this embodiment the first subsacrificial layer may be a semiconductor material and by a chemical vapor deposition process. The first sub-sacrificial layer is formed in the gap, and at this time, the first sub-sacrificial layer is not only filled in the gap between the piezoelectric resonance layer 1051 and the piezoelectric outer peripheral portion 1050, but also the upper surface of the piezoelectric resonance layer 1051 and the piezoelectric outer peripheral portion 1050. The first subsacrificial layer is then flattened to the tops of the piezoelectric resonance layer 1051 and the piezoelectric outer periphery 1050 by a chemical mechanical flattening (CMP) process. The sub-sacrificial layer is located only in the gap between the piezoelectric resonance layer 1051 and the piezoelectric outer peripheral portion 1050, and subsequently, based on the material of the first sub-sacrificial layer, of oxidation treatment, nitriding treatment and ion injection. An appropriate surface modification treatment process containing at least one type is selected, and the surface modification treatment is performed on the predetermined thickness of the top of the first sub-sacrificial layer to obtain a portion of the thickness thereof. The sub-sacrificial layer of 1 is converted into a second sub-sacrificial layer of another material, and the second sub-sacrificial layer and the remaining first sub-sacrificial layer below it that has not been surface-modified are The second sacrificial layer 106 is fully filled in the gap between the piezoelectric resonance layer 1051 and the piezoelectric outer peripheral portion 1050, and the thickness of the second sub-sacrificial layer needs to be formed after this. The depth of the recess 1081 is determined, after which the top surface of the filled second sacrificial layer 106 and the top surface of the surrounding piezoelectric resonance layer 1051 may not be flush due to the surface treatment process. It is vulnerable and disadvantageous to the subsequent deposition of the apical electrode layer 108, thus further flattening the apex of the second subsacrificial layer to the apex of the piezoelectric resonance layer 1051 by a chemical mechanical flattening (CMP) process. The top surface of the second sacrificial layer 106 and the top surface of the piezoelectric resonance layer 1051 around it are flushed again, thereby providing a flat operating surface for subsequent processes. do. Next, a second sub-sacrificial layer on the outer periphery of the effective working region (102A in FIG. 4H) of the bulk acoustic wave resonator to be manufactured corresponding to the second sacrificial layer 106 is formed by a combined process of photoetching and etching. Etching may be performed, etching may be stopped to the top surface of the first sub-sacrificial layer, or the etching may be stopped to the first sub-sacrificial layer to further form the first groove 107. Overetching may be present.

With reference to FIGS. 1A, 1B and 4G, in step S5, first, an appropriate method is selected based on the material of the apical electrode formed in advance, and the piezoelectric outer peripheral portion 1050, the piezoelectric resonance layer 1051, and the second The surfaces of the sacrificial layer 106 and the first groove 107 may be coated with a top electrode material layer (not shown), and the top is formed by, for example, physical vapor phase deposition such as magnetron sputtering vapor deposition or a chemical vapor phase deposition method. The electrode material layer may be formed, the top electrode material layer may be uniform in thickness at each position, and then a photoresist layer (not shown) with a defined top electrode pattern is lithographyed. By etching the top electrode material layer using the photoresist layer as a mask, the top electrode material layer (that is, the patterned top electrode material layer or the remaining top electrode material layer) is formed. ) 108 is formed, after which the photoresist layer is removed. The top electrode material layer may be any suitable conductive material or semiconductor material known in the art, and the conductive material may be a conductive metal material, for example, Al. One or more of Cu, Pt, Au, Mo, W, Ir, Os, Re, Pd, Rh and Ru, and the like, and the semiconductor material is, for example, Si, Ge, SiGe, SiC, SiGeC and the like. Is. In this embodiment, the top electrode layer 108 is formed from the top electrode resonance portion 1082 covered on the piezoelectric resonance layer 1051, the top electrode recess 1081 covered on the first groove 107, and the top electrode recess 1081. , The top electrode bridge portion 1080 extending to the outside of the top electrode recess 1081 and above the piezoelectric outer peripheral portion 1050 via the top surface of a part of the second sacrificial layer 106, the top electrode resonance portion 1082, and the top electrode resonance portion 1082. The top electrode recessed portion 1081 and the outer peripheral portion 1083 of the top electrode to be separated are included, and the outer peripheral portion 1083 of the top electrode is used as one metal contact of the bulk acoustic wave resonator to be formed in the region. It may be connected to one side facing the top electrode resonance portion 1082 of the bridge portion 1080, or may be separated from the top electrode bridge portion 1080 as a part of the top electrode bridge portion of the adjacent bulk acoustic wave resonator. In another embodiment of the present invention, the outer peripheral portion 1083 of the top electrode may be omitted. The upper surface shape of the top electrode resonance portion 1082 may be the same as or different from the shape of the piezoelectric resonance layer 1051. The area of the top electrode resonance portion 1082 is preferably larger than that of the piezoelectric resonance layer 1051 so as to be completely sandwiched between the electrode resonance portion 1042 and the electrode resonance portion 1042, which contributes to a reduction in the size of the device and a reduction in parasitic parameters. In another embodiment of the present invention, the shape of the top electrode resonance portion 1082 may be a polygon such as a quadrangle, a hexagon, a heptagon, or an octagon. The top electrode layer 108 may be used as an input electrode or an output electrode that receives or provides an electric signal such as a radio frequency (RF) signal. 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 is used as an input electrode. The piezoelectric resonance layer 1051 may convert an electric signal input via the top electrode resonance portion 1082 or the bottom electrode resonance portion 1042 into a bulk acoustic wave. For example, the piezoelectric resonant layer 1051 converts an electrical signal into a bulk acoustic wave by physical vibration. The apex electrode recess 1081 is provided along at least one side of the apex electrode resonance portion 1082 and is connected to the corresponding side of the apex electrode resonance portion 1082, that is, the apex electrode recess 1081 is the said. It is provided along the side of the apex electrode resonance portion 1082 and at least in the region where the apex electrode bridge portion 1080 and the apex electrode resonance portion 1082 are aligned. For example, the apex electrode recess portion 1081 is provided along the apex. A ring-closed structure is formed so as to surround the entire circumference of the electrode resonance portion 1082 (shown in FIGS. 2C and 2D, 2F). Since it has, it is not in contact with each other, and for example, the recessed portion 1081 of the top electrode extends on a plurality of continuous sides of the resonance portion 1082 of the top electrode to form an open ring structure (shown in FIGS. 2A and 2B). .. The top electrode bridge portion 1080 is electrically connected to the back side of the top electrode recessed portion 1081 with the top electrode resonance portion 1082, and a part of the second sacrificial layer is provided from above the top electrode recessed portion 1081. The top electrode bridge portion 1080 and the bottom electrode bridge portion 1040 extend to the top surface of a part of the etching protection layer 101 outside the second groove 102'via the top surface of the 106. , Mutual displacement (ie, they do not overlap in the region of the cavity 102), and at least one side of the second groove 102'is exposed from each of the top electrode bridge portion 1080 and the bottom electrode bridge portion 1040. .. In one embodiment of the present invention, with reference to FIGS. 2A and 2B, the top electrode recess 1081 projects the bottom electrode of the bottom electrode bridge portion 1040 in a direction perpendicular to the bottom surface of the second groove 102'. It does not overlap with the side facing the portion 1041, and the bottom electrode protruding portion 1041 does not overlap with the side of the top electrode bridge portion 1080 facing the top electrode recessed portion 1081. The projections of the top electrode bridge portion 1080 and the bottom electrode bridge portion 1040 on the bottom surface of the second groove 102'are either just connected or separated from each other, and the top electrode bridge portion 1080 is It may extend above a part of the substrate on the outer circumference of only one side of the second groove 102'.

With reference to FIGS. 1A, 1B and 4H, in step S6, the side facing the second groove 102'of the piezoelectric outer peripheral portion 1050 or the bulk by a combined process of photoetching and etching process or laser cutting. A hole may be drilled in the outer periphery of the device region of the acoustic wave resonator, and a part of the sacrificial protrusion 103', a part of the first sacrifice layer 103 other than the sacrifice protrusion 103', and a part of the second sacrifice layer 106. By forming an open hole (not shown) in which at least one of them can be exposed and then introducing a gas and / or a chemical solution into the open hole, the second sacrificial layer 106 and the sacrificial protrusion By removing the first sacrificial layer 103 having 103'and further emptying the second groove again, a cavity 102 is formed, and the cavity 102 is increased by the bottom electrode protrusion 1041. Includes a space of the groove 102', a space restricted by the top electrode recess 1081, and a space originally occupied by the second sacrificial layer 106 on both lower sides of the top electrode recess 1081. The bottom electrode resonance portion 1042, the piezoelectric resonance layer 1051 and the top electrode resonance portion 1082, which float above the cavity 102 and are laminated in this order, form an independent bulk acoustic thin film, and the bottom electrode resonance portion 1042, the piezoelectric resonance layer 1051, and the like. The portion where the top electrode resonance portion 1082 and the cavity 102 overlap each other in the vertical direction is an effective region, which is defined as an effective working region 102A, and the effective working region 102A receives electrical energy such as a radio frequency signal as a bottom electrode. When applied to the resonance portion 1042 and the top electrode resonance portion 1082, vibration and resonance occur in the thickness direction (that is, the vertical direction) of the piezoelectric resonance layer 1051 due to the piezoelectric phenomenon generated in the piezoelectric resonance layer 1051, and the cavity 102. The other region is an invalid region 102B, which is a region that does not resonate due to the piezoelectric phenomenon even when electrical energy is applied to the top electrode layer 108 and the bottom electrode layer 104. The bulk acoustic thin film, which floats above the effective working region 102A and is composed of the bottom electrode resonance portion 1042, the piezoelectric resonance layer 1051 and the top electrode resonance portion 1082, which are sequentially laminated, corresponds to the vibration of the piezoelectric phenomenon of the piezoelectric resonance layer 1051. It is possible to output a radio frequency signal having a resonance frequency. Specifically, when electrical energy is applied to the top electrode resonance portion 1082 and the bottom electrode resonance portion 1042, a bulk acoustic wave is generated by the piezoelectric phenomenon generated in the piezoelectric resonance layer 1051. In this case, the generated bulk acoustic wave has not only a desirable longitudinal wave but also a parasitic transverse wave, and the transverse wave is blocked by the top electrode recess 1081 and the bottom electrode protrusion 1041 and is limited to the effective operating region 102A, and the outer periphery of the cavity is limited. Prevents propagation in the membrane layer in, thereby improving the acoustic wave loss due to the transverse wave propagating to the membrane layer at the outer periphery of the cavity, thereby improving the quality coefficient of the resonator and ultimately. The performance of the device can be improved.

It should be noted that step S6 may be performed after all the membrane layers above the cavity 102 to be formed have been made, thereby subsequently providing the first sacrificial layer 103 and the second sacrificial layer 106. It can be used to protect the space in which the cavity 102 is located and the film layer structure laminated by the bottom electrode layer 104 to the top electrode layer 108 formed on the cavity 102, and after the cavity 102 is formed, it is subsequently followed. Avoid the risk of cavity collapse caused when performing the process. Also, the open hole formed in step S6 may be left behind so that the open hole can be sealed and the cavity 102 can be further sealed in a subsequent packaging process such as coupling of two substrates.

In step S1 of the method for manufacturing a bulk acoustic wave resonator of each of the above embodiments, the first groove is formed by etching the substrate to form the second groove 102'and fill the second groove 102'. The cavity 102 formed in step S6 by forming the sacrificial layer on a part of the substrate has a groove structure in which the entire bottom portion is recessed in the substrate, but the technical solution of the present invention is limited to this. I can't. In step S1 of another embodiment of the present invention, further, by forming a first sacrificial layer 103 that is entirely projected onto the substrate by a combination process of film layer deposition and photoetching and etching, step S6. The cavity formed in (1) has a cavity structure in which the entire cavity is projected onto the substrate surface. Specifically, with reference to FIGS. 2E and 5, in step S1, a groove 102'for manufacturing the cavity is formed. The first sacrificial layer 103 is first coated on the etching protective layer 101 on the surface of the base 100 without being formed on the provided substrate, and then the first sacrificial layer 103 is patterned by a combined process of photoetching and etching. Then, only the first sacrificial layer 103 covered on the region 102 is left, and the first sacrificial layer 103 is further formed on a part of the substrate, and the first sacrificial layer 103 is wide from top to bottom. The first sacrificial material layer for manufacturing the sacrificial protrusion 103'after determining the depth of the cavity 102 to be formed thereafter by the thickness of the first sacrificial layer 103. The sacrificial layer 103 and the substrate are coated, and then the sacrificial protrusion 103'is formed on a part of the first sacrificial layer 103 by a combined process of photoetching and etching. In this embodiment, the corresponding side walls of the formed bottom electrode outer peripheral portion 1043, bottom electrode bridge portion 1040, piezoelectric outer peripheral portion 1050, top electrode outer peripheral portion 1083, and top electrode bridge portion 1080 project a first sacrificial layer. It is necessary to be deformed to adapt to 103 so that all the vertical sections have a "Z" -shaped structure, and the subsequent step is a method for manufacturing a bulk acoustic wave resonator according to an embodiment shown in FIGS. 4A to 4H. It is exactly the same as the corresponding part in, and will not be explained in detail here.

The bulk acoustic wave resonator of the present invention preferably uses the method for manufacturing the bulk acoustic wave resonator of the present invention to manufacture the bottom electrode bridge portion, the bottom electrode protrusion portion, and the bottom electrode resonator portion by the same process. The top electrode bridge part, top electrode recess part and top electrode resonance part are manufactured by the same process, further simplifying the process and reducing the manufacturing cost.

Of course, one of ordinary skill in the art can make various changes and modifications to the invention without departing from the gist and scope of the invention. Thus, as these modifications and variations of the invention fall within the claims of the invention and their equivalent technology, the invention is intended to include these modifications and modifications.

100 Base 101 Etching protection layer 102 Cavity 102'Second groove 102A Effective working area 102B Invalid area 103 First sacrificial layer 1033' Sacrificing protrusion 104 Bottom electrode layer (that is, the remaining bottom electrode material layer)
1040 Bottom electrode bridge part 1041 Bottom electrode protruding part 1042 Bottom electrode resonance part 1043 Outer peripheral part of bottom electrode 105 Piezoelectric material layer 1050 Hydraulic outer peripheral part 1051 Hydraulic resonance layer (or called piezoelectric resonance part)
106 Second sacrificial layer 107 Sacrificial protrusion 108 Top electrode layer (ie, remaining top electrode material layer)
1080 Top electrode bridge part 1081 Top electrode recess 1082 Top electrode resonance part 1083 Outer peripheral part of top electrode

Claims (23)

It is a bulk acoustic wave resonator,
With the board
A bottom electrode layer provided on the substrate, in which a cavity is formed between the bottom electrode layer and the substrate, and the bottom electrode layer is located in the region of the cavity and is separated from the bottom surface of the cavity. A bottom electrode layer having a bottom electrode protrusion protruding in the direction,
A piezoelectric resonance layer formed on the bottom electrode layer above the cavity,
A top electrode layer formed on the piezoelectric resonance layer, wherein the top electrode layer is located in the region of the cavity and has a top electrode recessed portion recessed in a direction close to the bottom surface of the cavity. The top electrode recess and the bottom electrode protrusion are both located in the cavity region on the outer periphery of the piezoelectric resonance layer, and the bottom electrode protrusion and the top electrode recess both surround the piezoelectric resonance layer. A bulk acoustic wave resonator that extends in the peripheral direction and includes a top electrode layer that is at least partially opposed to each other. The bottom electrode layer further includes a bottom electrode bridge portion having one end connected to the bottom electrode protrusion and the other end abutting on the substrate at the outer periphery of the cavity.
The top electrode layer further includes a top electrode bridge portion having one end connected to the top electrode recess and the other end extending above the substrate on the outer periphery of the cavity.
The bulk acoustic wave resonator according to claim 1, wherein the bottom electrode bridge portion and the top electrode bridge portion are displaced from each other. The bottom electrode layer further includes a bottom electrode resonance portion that overlaps with the piezoelectric resonance layer.
The top electrode layer further includes a top electrode resonance portion that overlaps with the piezoelectric resonance layer.
The bulk acoustic wave resonator according to claim 2, wherein both the bottom electrode resonance portion and the top electrode resonance portion are polygonal. The bottom electrode protrusion is provided along the side of the bottom electrode resonance portion, and is provided at least in a region where the bottom electrode bridge portion and the bottom electrode resonance portion are aligned.
The top electrode recess is provided along the side of the top electrode resonance portion, and is provided at least in a region where the top electrode bridge portion and the top electrode resonance portion are aligned. Item 3. The bulk acoustic wave resonator according to Item 3. The bottom electrode protrusion is displaced from the top electrode bridge at least above the cavity, or the bottom electrode protrusion surrounds the entire circumference of the bottom electrode resonance portion.
The top electrode recess is characterized in that, above the cavity, at least the bottom electrode bridge portion is displaced from each other, or the top electrode recess portion surrounds the entire circumference of the top electrode resonance portion. The bulk acoustic wave resonator according to claim 4. The bulk acoustic wave resonance according to claim 5, wherein the projections of the top electrode recess and the bottom electrode protrusion on the bottom surface of the cavity are just connected, offset from each other, or overlap each other. vessel. The bottom electrode protrusion, the bottom electrode bridge portion, and the bottom electrode resonance portion are formed of the same film layer.
The bulk acoustic wave resonator according to claim 3, wherein the top electrode recess portion, the top electrode bridge portion, and the top electrode resonance portion are formed of the same membrane layer. The bottom electrode bridge portion is characterized in that it completely covers the cavity above a part of the cavity in which it is located and does not overlap with the top electrode bridge portion in the width direction of the top electrode bridge portion. The bulk acoustic wave resonator according to claim 4. The horizontal distance between the bottom electrode protrusion and the piezoelectric resonance layer is the minimum distance allowed in the process of manufacturing the bottom electrode protrusion.
One of claims 1 to 8, wherein the horizontal distance between the top electrode recess and the piezoelectric resonance layer is the minimum distance allowed in the process of manufacturing the top electrode recess. The bulk acoustic wave resonator described in the section. The side wall of the recessed portion of the top electrode is inclined with respect to the top surface of the piezoelectric resonance layer.
The bulk acoustic wave resonator according to any one of claims 1 to 8, wherein the side wall of the bottom electrode protrusion is inclined with respect to the bottom surface of the piezoelectric resonance layer. The angle between the side wall of the top electrode recess and the top surface of the piezoelectric resonance layer is 45 degrees or less.
The bulk acoustic wave resonator according to claim 10, wherein the angle between the side wall of the bottom electrode protrusion and the bottom surface of the piezoelectric resonance layer is 45 degrees or less. The line width of the bottom electrode protrusion is the minimum line width allowed in the process of manufacturing the bottom electrode protrusion.
The line width of the apex electrode recess is the minimum line width allowed in the process of manufacturing the apex electrode recess, according to any one of claims 1 to 8 or 11. Bulk acoustic wave resonator. The cavity has a groove structure in which the entire bottom portion is recessed in the substrate, or a cavity structure in which the entire protrusion is provided on the surface of the substrate, according to any one of claims 1 to 8 or 11. The bulk acoustic wave resonator according to claim 1. A filter comprising at least one bulk acoustic wave resonator according to any one of claims 1 to 13. A radio frequency communication system comprising at least one filter according to claim 14. It is a manufacturing method of bulk acoustic wave resonators.
A step of providing a substrate and forming a first sacrificial layer with sacrificial protrusions on some of the substrates.
A step of forming a bottom electrode layer on the first sacrificial layer and forming a portion of the bottom electrode layer covering the surface of the sacrificial protrusion as a bottom electrode protrusion.
A step of forming a piezoelectric resonance layer that exposes the bottom electrode protrusion on the bottom electrode layer,
A step of forming a second sacrificial layer having a first groove in an exposed region around the piezoelectric resonance layer.
The top electrode layer is formed on the piezoelectric resonance layer and a part of the second sacrificial layer around the piezoelectric resonance layer, and the portion of the top electrode layer covering the first groove is used as a top electrode recess. Steps to form and
It is a step of removing the second sacrificial layer and the first sacrificial layer having the sacrificial protrusion, and forming a cavity at the position of the second sacrificial layer and the first sacrificial layer having the sacrificial protrusion. The top electrode recess and the bottom electrode protrusion are both located in the cavity region on the outer periphery of the piezoelectric resonance layer, and the bottom electrode protrusion and the bottom electrode recess both form the piezoelectric resonance layer. A method of manufacturing a bulk acoustic wave resonator, characterized in that it extends in the enclosed peripheral direction and includes a step in which the two are at least partially opposed to each other. The step of forming the first sacrificial layer having the sacrificial protrusion on a part of the substrate is a step of forming a groove on the substrate by etching the substrate and forming the first sacrificial layer. By coating the first sacrificial layer and the substrate with the sacrificial material layer and patterning the sacrificial material layer, the sacrificial protrusion is partially covered with the first sacrificial layer. Includes, or includes, a step of forming to project into
The step of forming the first sacrificial layer having the sacrificial protrusion on a part of the substrate is a step of coating the substrate with the first sacrificial layer and patterning the first sacrificial layer. A step of forming the first sacrificial layer so as to project from a part of the substrate, and covering the first sacrificial layer and the substrate with the sacrificial material layer to pattern the sacrificial material layer. 16. The method of manufacturing a bulk acoustic wave resonator according to claim 16, further comprising a step of forming the sacrificial protrusion so as to project onto a portion of the first sacrificial layer. The step of removing the second sacrificial layer and the first sacrificial layer having the sacrificial protrusion is
After forming the apex electrode layer, at least one opening that exposes at least a part of the second sacrificial layer, a part of the sacrificial protrusion, or a part of the first sacrificial layer other than the sacrificial protrusion. The steps to form the holes and
16. The claim 16 comprises the step of removing the second sacrificial layer and the first sacrificial layer having the sacrificial protrusion by introducing a gas and / or a chemical solution into the opening hole. The method for manufacturing a bulk acoustic wave resonator according to the description. The steps for forming the bottom electrode layer are sequentially connected by a step of depositing the bottom electrode material layer so as to cover the first sacrificial layer having the sacrificial protrusion and a step of patterning the bottom electrode material layer. In the step of forming the bottom electrode bridge portion, the bottom electrode protrusion portion, and the bottom electrode resonance portion, the bottom electrode resonance portion overlaps with the piezoelectric resonance layer, and the bottom electrode faces back to the bottom electrode protrusion portion. The method for manufacturing a bulk acoustic wave resonator according to any one of claims 16 to 18, further comprising a step in which one end of a bridge portion abuts on the substrate at the outer periphery of the cavity. The step of forming the top electrode layer is a step of depositing the top electrode material layer so as to cover the second sacrificial layer having the first groove and the piezoelectric resonance layer, and patterning the top electrode material layer. By doing so, it is a step of forming the apex electrode bridge portion, the apex electrode recessed portion, and the apex electrode resonance portion connected in order, and the apex electrode resonance portion and the piezoelectric resonance layer overlap each other, and the apex electrode recessed portion One end of the top electrode bridge portion facing back to the top extends above the substrate on the outer periphery of the cavity, and the top electrode bridge portion and the bottom electrode bridge portion include a step of being displaced from each other. The method for manufacturing a bulk acoustic wave resonator according to claim 19. Both the bottom electrode resonance portion and the top electrode resonance portion are polygonal.
The bottom electrode protrusion is provided along the side of the bottom electrode resonance portion, and is provided at least in a region where the bottom electrode bridge portion and the bottom electrode resonance portion are aligned.
The top electrode recess is provided along the side of the top electrode resonance portion, and is provided at least in a region where the top electrode bridge portion and the top electrode resonance portion are aligned. Item 20. The method for manufacturing a bulk acoustic wave resonator according to Item 20. The horizontal distance between the bottom electrode protrusion and the piezoelectric resonance layer is the minimum distance allowed in the process of manufacturing the bottom electrode protrusion.
16 to 18 and 20 are characterized in that the horizontal distance between the apex electrode recess and the piezoelectric resonance layer is the minimum distance allowed in the process of manufacturing the apex electrode recess. 21. The method for manufacturing a bulk acoustic wave resonator according to any one of Items. The line width of the bottom electrode protrusion is the minimum line width allowed in the process of manufacturing the bottom electrode protrusion.
One of claims 16 to 18 and claims 20 to 21, wherein the line width of the top electrode recess is the minimum line width allowed in the process of manufacturing the top electrode recess. The method for manufacturing a bulk acoustic wave resonator according to the above.

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