JP7199758B2 - Bulk acoustic wave resonator, manufacturing method thereof, filter, radio frequency communication system - Google Patents

Description

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

Radio frequency (RF) communications, such as those used in cell phones, require the use of radio frequency filters, each of which transmits desired frequencies 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, on the premise that frequency resources are limited and the need to use as few mobile communication devices as possible, it is difficult to improve the transmission power of wireless power transmission devices such as radio base stations, micro base stations or repeaters. , becomes a matter of consideration and also means that the filter power requirements in the front-end circuits of mobile communication devices are also high.

Conventionally, high-power filters in devices such as wireless base stations are mainly cavity filters, whose power reaches 100 watts, but the size of such filters is too large. Some devices use dielectric filters, 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 deficiencies of the above two filters. Bulk acoustic wave resonators have volume advantages incomparable with ceramic dielectric filters, operating frequency and power capacity advantages incomparable with surface acoustic wave (SAW) resonators, and are a trend of current wireless communication systems. 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. A standing wave is formed in the form of an acoustic wave in a filter composed of acoustic wave resonators. Since the speed of acoustic waves is five orders of magnitude smaller than that of electromagnetic waves, the size of filters composed of bulk acoustic wave resonators is smaller than that of conventional dielectric filters.

The working principle of one type of cavity bulk acoustic wave resonator is to use acoustic waves to reflect at the interface between the bottom electrode or support layer and the air, confining the acoustic waves to the piezoelectric layer to achieve resonance. It has advantages such as high Q factor, low insertion loss, and integrability, and is widely adopted.

However, conventionally fabricated cavity-type bulk acoustic wave resonators cannot further improve their quality factor (Q) and meet the demands of high-performance radio frequency systems.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a bulk acoustic wave resonator, a method for manufacturing the same, a filter, and a radio frequency communication system that can improve the quality factor and the performance of the device.

In order to achieve the above object, according to the present invention,
a substrate;
A bottom electrode layer provided on the substrate, wherein a cavity is formed between the bottom electrode layer and the substrate, and a portion of the bottom electrode layer located above the cavity extends flat. a bottom electrode layer;
a piezoelectric resonance layer formed on the bottom electrode layer in an upper portion of the cavity;
A top electrode layer formed on the piezoelectric resonance layer, the top electrode layer being located in the region of the cavity on the outer periphery of the piezoelectric resonance layer, protruding away from the bottom surface of the cavity, and A bulk acoustic wave resonator is provided including a top electrode layer having a peripherally extending top electrode protrusion surrounding the layer.

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

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

Moreover, according to the present invention,
providing a substrate and forming a first sacrificial layer having a flat top surface on a portion of the substrate;
forming a bottom electrode layer on a portion of the first sacrificial layer, the portion located on the top surface of the first sacrificial layer extending flatly;
forming a piezoelectric resonance layer on the bottom electrode layer exposing a portion of the first sacrificial layer and a portion of the bottom electrode layer;
forming a second sacrificial layer having sacrificial protrusions in exposed regions around the piezoelectric resonance layer;
A top electrode layer is formed on the piezoelectric resonance layer and a portion of the second sacrificial layer surrounding the piezoelectric resonance layer, and a portion of the top electrode layer covering the sacrificial protrusion is formed as a top electrode protrusion. a step;
removing the second sacrificial layer and the first sacrificial layer with the sacrificial protrusion and forming a cavity at the location of the second sacrificial layer and the first sacrificial layer with the sacrificial protrusion; wherein the top electrode protrusion is located in the region of the cavity at the outer periphery of the piezoelectric resonance layer and extends in the peripheral direction surrounding the piezoelectric resonance layer. A method is provided.

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 electrode and the top electrode, the piezoelectric phenomenon induced in the piezoelectric resonance layer produces a desired longitudinal wave propagating in the thickness direction and an undesirable transverse wave propagating along the plane of the piezoelectric resonance layer. Then, the transverse wave is blocked by the projection of the top electrode on the cavity floating on the outer periphery of the piezoelectric resonance layer, reflected by the area corresponding to the piezoelectric resonance layer, and propagated to the film layer on the outer periphery of the cavity. This can improve the acoustic loss, improve the quality factor of the resonator, and ultimately improve 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 extend continuously above the substrate at the periphery of the cavity, and the effective operation of the bulk acoustic wave resonator The area can be completely confined to the cavity area, with both the bottom and top electrode bridges extending to only some sides of the cavity (i.e., the bottom and top electrode layers ), which reduces the influence of the membrane layer around the cavity on longitudinal vibrations induced in the piezoelectric resonant layer, improving performance.

3. Even if the top electrode protruding part and the bottom electrode layer have overlapping parts, there is a gap structure between the overlapping parts, so that the parasitic parameters can be greatly reduced, and the top electrode layer and the bottom electrode layer Problems such as electrical contact in the cavity region of the bottom electrode layer can be avoided and device reliability can be improved.

4. The overlapping portions of the bottom electrode bridge portion and the top electrode bridge portion with the cavity are all floating, and the bottom electrode bridge portion and the top electrode bridge portion are mutually displaced from the region of the cavity (that is, both , do not overlap in the cavity region), which can greatly reduce the parasitic parameters, avoid problems such as leakage and short circuits caused by contact between the bottom electrode bridge and the top electrode bridge, and make the device reliability can be improved.

5. The bottom electrode bridge completely covers the cavity above the portion of the cavity in which it is located, thereby using a large area bottom electrode bridge to strongly attach to the membrane layer above it. provide good mechanical support, thereby avoiding the problem of device failure due to cavity collapse.

6. The top electrode protrusion surrounds the entire periphery of the top electrode resonator, blocking transverse waves from the periphery of the piezoelectric resonance layer in all directions, and obtaining a better quality factor.

7. 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 projection part, the top electrode resonance part and the top electrode bridge part are formed of the same film layer, The thickness of the top electrode protrusion is uniform, which simplifies the process and reduces the cost. Device reliability can be improved without disconnection situations.

8. The portion of the bottom electrode layer in the cavity region is flat, on the one hand, it can contribute to the improvement of the thickness uniformity of the thin film in the effective region, and on the other hand, it is good for the etching process when forming the piezoelectric resonance layer. It contributes to a reduction in difficulty and avoids the problem of not completely etching the piezoelectric material because the top surface of the bottom electrode layer is not flat, thereby reducing the parasitic parameters.

1 is a top structural schematic diagram of a bulk acoustic wave resonator according to an embodiment of the present invention; FIG. FIG. 2 is a schematic cross-sectional view taken along lines XX' and YY' in FIG. 1; FIG. 2 is a schematic cross-sectional view taken along lines XX' and YY' in FIG. 1; FIG. 4 is a top structural schematic diagram of a bulk acoustic wave resonator according to another embodiment of the present invention; FIG. 4 is a top structural schematic diagram of a bulk acoustic wave resonator according to another embodiment of the present invention; FIG. 4 is a top structural schematic diagram of a bulk acoustic wave resonator according to another embodiment of the present invention; FIG. 5 is a schematic cross-sectional view of a bulk acoustic wave resonator according to another embodiment of the present invention; 1 is a flow chart of a method for manufacturing a bulk acoustic wave resonator according to one embodiment of the present invention; It is a cross-sectional schematic diagram along XX' in FIG. 1A in the manufacturing method of the bulk acoustic wave resonator of one Example of this invention. It is a cross-sectional schematic diagram along XX' in FIG. 1A in the manufacturing method of the bulk acoustic wave resonator of one Example of this invention. It is a cross-sectional schematic diagram along XX' in FIG. 1A in the manufacturing method of the bulk acoustic wave resonator of one Example of this invention. It is a cross-sectional schematic diagram along XX' in FIG. 1A in the manufacturing method of the bulk acoustic wave resonator of one Example of this invention. It is a cross-sectional schematic diagram along XX' in FIG. 1A in the manufacturing method of the bulk acoustic wave resonator of one Example of this invention. It is a cross-sectional schematic diagram along XX' in FIG. 1A in the manufacturing method of the bulk acoustic wave resonator of one Example of this invention. 1B is a schematic cross-sectional view along XX' in FIG. 1A in the method for manufacturing a bulk acoustic wave resonator according to another embodiment of the present invention; FIG.

The technical solutions of the present invention are further described in detail below with reference to the drawings and specific embodiments. Based on the following description, the effects and features of the present invention will become clearer. It should be noted that the drawings are all in a greatly simplified form, imprecise proportions, and are merely for the purpose of providing an easy, clear and supplemental explanation of the embodiments of the present invention. Similarly, to the extent that the methods described herein include a series of steps, the order of these steps presented herein is not the only order in which these steps may be performed, and some said steps may include: Some other steps may be omitted and/or not described herein may be added to the method. Further, what is meant herein by "relatively offset" is that they do not overlap in the cavity area, ie their projections at the bottom of the cavity do not overlap.

1A to 1C, FIG. 1A is a top structural schematic diagram of a bulk acoustic wave resonator of one embodiment of the present invention, and FIG. 1B is a cross-sectional structural schematic diagram along XX' in FIG. FIG. 1C is a schematic cross-sectional view along line YY' in FIG. and layer 108 .

The substrate includes a base 100 and an etching protection layer 101 coated on the base 100 . The base 100 may be any suitable substrate known to those skilled in the art, such as silicon (Si), germanium (Ge), silicon germanium (SiGe), silicon carbide (SiC), silicon germanium carbide (SiGeC), indium arsenide (InAs), gallium arsenide (GaAs), indium phosphide (InP), or other III/V compound semiconductors, multilayer structures composed of these semiconductors, etc. May be one or Silicon on Insulator (SOI), Stacked Silicon on Insulator (SSOI), Stacked Silicon Germanium on Insulator (S-SiGeOI), Stacked Silicon Germanium on Insulator (SiGeOI) and Germanium on Insulator (GeOI), or Double Side Polished Wafers (DSP), ceramic-based such as aluminum oxide, Sekiei , or may be a glass base or the like. The material of the etching protection layer 101 may be any suitable dielectric material, including but not limited to at least one of silicon oxide, silicon nitride, silicon nitrogen oxide, silicon carbonitride, and the like. can't The etching protection layer, on the other hand, improves the structural stability of the finally manufactured bulk acoustic wave resonator, strengthens the isolation between the bulk acoustic wave resonator and the base 100, and reduces the resistivity requirements for the base 100. can be reduced while protecting other areas of the substrate from being etched during fabrication of the bulk acoustic wave resonator, thereby improving device performance and reliability.

A cavity 102 is formed between the bottom electrode layer 104 and the substrate. 1A-1C, in this embodiment, the cavity 102 may be formed by sequentially etching the thickness of the etching protection layer 101 and part of the base 100 by an etching process, and the bottom The whole becomes a groove structure recessed in the substrate. However, the technique of the present invention is not limited to this, and referring to FIG. 2D, in another embodiment of the present invention, the cavity 102 is followed by a sacrificial layer protruding from the surface of the etching protection layer 101 . Through the process of removing using a removing method, it may be formed above the top surface of the etching protection layer 101 , resulting in a cavity structure that protrudes over the surface of said etching protection layer 101 as a whole. Also, in this embodiment, the shape of the bottom surface of the cavity 102 may be rectangular, but in other embodiments of the present invention, the shape of the bottom surface of the cavity 102 may also be circular, elliptical, or other than rectangular. polygon (eg, pentagon, hexagon).

The piezoelectric resonant layer 1051, which may be called a piezoelectric resonant part, is located in the upper region of the cavity 102 (i.e., located within the region of the cavity 102) and corresponds to the effective working area of the bulk acoustic wave resonator. and 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 and a bottom electrode resonance portion 1041 which are connected in sequence, and the portion of the bottom electrode layer 104 located above the cavity 102 extends flatly, that is, The top surface of the portion of the bottom electrode bridge portion 1040 located above the cavity and the top surface of the bottom electrode resonance portion 1041 are flush with each other, and the bottom surface of the portion of the bottom electrode bridge portion 1040 located above the cavity and the top surface of the bottom electrode resonance portion 1041 are flush with each other. The bottom surface of the bottom electrode resonance portion 1041 is flush with the bottom surface. The top electrode layer 108 includes a top electrode bridge portion 1080, a top electrode protrusion portion 1081, and a top electrode resonance portion 1082, which are connected in order. , the bottom electrode resonator 1041, the piezoelectric resonator layer 1051, and the top electrode resonator 1082, which form an effective operating area 102A of the bulk acoustic wave resonator. A portion other than 102A is an ineffective region 102B, and the piezoelectric resonance layer 1051 is located in the effective operating region 102A and is separated from the film layers surrounding the cavity 102 to make the effective operating region of the bulk acoustic wave resonator into the cavity 102A. to reduce the influence of the film layers around the cavity on the longitudinal vibrations induced in the piezoelectric resonant layer, reduce the parasitic parameters induced in the dead region 102B, and improve the performance of the device. can be improved. The bottom electrode resonant portion 1041, the piezoelectric resonant layer 1051, and the top electrode resonant portion 1082 all have a flat structure with flat upper and lower surfaces, and the top electrode protruding portion 1081 is located at the outer periphery of the effective operating region 102A in the cavity 102B. It is positioned above, is electrically connected to the top electrode resonator 1082 , and protrudes away from the bottom surface of the cavity 102 . The entire top electrode protrusion 1081 protrudes upward with respect to the top surface of the top electrode resonance portion 1082 and is located within the cavity region (ie, 102B) at the outer circumference of the piezoelectric resonance layer 1051 . The top electrode protrusion 1081 may have a solid structure or a hollow structure, and preferably has a hollow structure. It avoids the collapsing deformation of the top electrode resonant part 1082 and the piezoelectric resonant layer 1051 and the bottom electrode resonant part 1041 caused by the solid top electrode protrusion 1081, and further improves the resonance coefficient. Both the bottom electrode resonance portion 1041 and the top electrode resonance portion 1082 are polygonal (the top surface and the bottom surface are both polygonal), and the shapes of the bottom electrode resonance portion 1041 and the top electrode resonance portion 1082 are may be similar (shown in FIGS. 2A and 2C) or completely identical (shown in FIGS. 1A and 2B). The piezoelectric resonance layer 1051 has a polygonal structure similar to the shapes of the bottom electrode resonance part 1041 and the top electrode resonance part 1082 .

1A to 1C, in this embodiment, the bottom electrode layer 104, the piezoelectric resonance layer 1051 and the top electrode layer 108 constitute a "watch"-like film layer structure, and the bottom electrode bridge portion 1040 is the bottom electrode resonance layer. Aligned with one corner of portion 1041, with top electrode bridge portion 1080 aligned with one corner of top electrode resonator portion 1082, bottom electrode bridge portion 1040 and top electrode bridge portion 1080 form two bands of a "watch". and the top electrode projecting portion 1081 is provided along the side of the top electrode resonant portion 1082 and is provided only in a region where the top electrode bridge portion 1080 and the top electrode resonant portion 1082 are aligned. The top electrode protrusion 1081 corresponds to the connection structure between the dial of a "watch" and one band, and includes the bottom electrode resonance part 1041, the piezoelectric resonance layer 1051, and the top electrode resonance part in the effective area 102A. The laminated structure of 1082 corresponds to the dial of a wrist watch, in which the band part is connected to the film layer on the substrate around the cavity, and the remaining parts are all connected to the cavity around the cavity through the cavity. Separated from the membrane layer on the substrate. That is, in this embodiment, the top electrode protrusion 1081 extends around the piezoelectric resonance layer 1051 in the peripheral direction, and the top electrode protrusion 1081 extends along the peripheral direction of the piezoelectric resonance layer 1051. , the top electrode protrusion 1081 and the bottom electrode bridge 1040 are located on both sides of the piezoelectric resonance layer 1051, and refer to the plane where the piezoelectric resonance layer 1051 is located. 1080 and 1040, which contributes to reducing the area of the invalid region 102B not covered by the top electrode bridge portion 1080 and the bottom electrode bridge portion 1040. and the area of the top and bottom electrode bridges 1080 and 1040, further reducing the parasitic parameters and improving the electrical performance of the device. The bottom electrode bridge part 1040 is electrically connected to one side of the bottom electrode resonance part 1041 and is a cavity (ie, 102B) floating above the bottom electrode resonance part 1041 to the outside of the bottom electrode resonance part 1041 . , and extends to above a portion 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 resonance portion 1082 of the top electrode projecting portion 1081 . is electrically connected to the side opposite to the top electrode protrusion 1081, and after passing above the cavity (that is, 102B) floating outside the top electrode protrusion 1081, the cavity 102 Extending above a portion of the etching protection layer 101 at the perimeter, the bottom electrode bridge portion 1040 and the top electrode bridge portion 1080 extend above the substrate outside two opposite sides of the cavity 102. At this time, the bottom electrode bridge portion 1040 and the top electrode bridge portion 1080 are mutually offset (i.e., do not overlap) in the cavity 102 region, thereby reducing parasitic parameters and reducing the bottom electrode Problems such as leaks and short circuits due to contact between the 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 the corresponding signal to the bottom electrode resonance portion 1041 by connecting the corresponding signal line, and the top electrode bridge portion 1080 connects the corresponding signal line. is used to transfer a corresponding signal to the top electrode resonator 1082 via the top electrode protrusion 1081, thereby enabling the bulk acoustic wave resonator to operate normally, specifically the bottom electrode. By applying a time-varying voltage to the bottom electrode resonance portion 1041 and the top electrode resonance portion 1082 via the electrode bridge portion 1040 and the top electrode bridge portion 1080, respectively, a longitudinal extension mode or a “piston” mode is excited. , the piezoelectric resonance layer 1051 converts energy in the form of electrical energy into longitudinal waves, generating parasitic transverse waves in the process, and the top electrode protrusions 1081 allow these transverse waves to propagate to the membrane layers at the perimeter of the cavity. It can be blocked and confined to the region of the cavity 102, thereby avoiding energy losses due to shear waves and improving the quality factor.

Preferably, the line width of the top electrode protrusion 1081 is the minimum line width allowed for the corresponding process, and the horizontal distance between the top electrode protrusion 1081 and the piezoelectric resonance layer 1051 is the same as the corresponding process. This is the minimum allowable distance for the top electrode protrusion 1081, which allows the top electrode protrusion 1081 to achieve a desired transverse wave blocking effect and contributes to a reduction in device area.

Also, the side wall of the top electrode protrusion 1081 is a side wall inclined with respect to the top surface of the piezoelectric resonance layer, and as shown in FIG. has a trapezoidal or trapezoidal-like shape, and the angles α1 and α2 between the two sidewalls of the top electrode protrusion 1081 and the top surface of the piezoelectric resonance layer 1051 are both 45 degrees or less. This avoids that the side wall of the top electrode protrusion 1081 is too vertical, causing the top electrode protrusion 1081 to be cut and further affecting the effect of transferring the signal to the top electrode resonance part 1082, Also, the thickness uniformity of the entire top electrode layer 108 can be further improved.

In one preferred embodiment of the present invention, the bottom electrode resonator portion 1041 and the bottom electrode bridge portion 1040 are formed in the same film layer manufacturing process (that is, the same film layer manufacturing process), and the top electrode resonator portion 1082 and the top electrode bridge portion 1082 are formed in the same film layer manufacturing process. The electrode protruding portion 1081 and the top electrode bridge portion 1080 are formed in the same film layer manufacturing process (that is, the same film layer manufacturing process), that is, the bottom electrode resonance portion 1041 and the bottom electrode bridge portion 1040 are integrally manufactured. The top electrode resonator portion 1082, the top electrode protrusion portion 1081 and the top electrode bridge portion 1080 are integrally fabricated film layers, which simplifies the process, reduces the cost, and reduces the cost of the bottom electrode. The film layer materials for fabricating the resonator portion 1041 and the bottom electrode bridge portion 1040, and the film layer materials for fabricating the top electrode resonator portion 1082, the top electrode protrusion portion 1081, and the top electrode bridge portion 1080 are Any suitable conductive or semiconductor material known in the art may be used, and the conductive material may be a metallic material having electrical conductivity, such as aluminum (Al), copper (Cu) , platinum (Pt), gold (Au), molybdenum (Mo), tungsten (W), iridium (Ir), osmium (Os), rhenium (Re), palladium (Pd), rhodium (Rh) and ruthenium (Ru) and the semiconductor material is, for example, Si, Ge, SiGe, SiC, SiGeC, or the like. In other embodiments of the present invention, the bottom electrode resonator portion 1041 and the bottom electrode bridge portion 1040 may be formed by different film layer manufacturing processes, subject to process cost and process technology permitting, and the top electrode resonator portion 1082, top electrode protrusion 1081 and top electrode bridge 1080 may be formed by different film layer manufacturing processes.

2A-2C, the top electrode protrusion 1081 extends to more continuous sides of the top electrode resonator 1082 to further improve the transverse wave blocking effect. For example, referring to FIG. 2A, the piezoelectric resonance layer 1051, the top electrode resonance part 1082 and the bottom electrode resonance part 1041 are all pentagonal planar structures, the area of the piezoelectric resonance layer 1051 is the smallest, and the top electrode resonance part 1082 is larger than that, and the area of the bottom electrode resonance portion 1041 is the largest, and the top electrode projection portion 1081 is provided along a plurality of sides of the top electrode resonance portion 1082 and connected to these sides, The projection of the connecting portion between the electrode resonance portion 1041 and the bottom electrode bridge portion 1040 on the bottom surface of the cavity 102 is exposed from the projection of the top electrode protrusion portion 1081 on the bottom surface of the cavity 102 . and the bottom electrode bridge portion 1040 are prevented from overlapping each other, and the parasitic parameter can be further reduced. For example, referring to FIG. 2B, the piezoelectric resonance layer 1051, the top electrode resonance section 1082, and the bottom electrode resonance section 1041 all have a pentagonal planar structure, the area of the piezoelectric resonance layer 1051 is the smallest, and the top electrode resonance section 1082 and the bottom electrode resonance portion 1041 have the same or substantially the same area, shape, etc., and the top electrode protruding portion 1081 surrounds the top electrode resonance portion 1082 and The bottom electrode resonance portion 1041 and the projection on the bottom surface of the cavity 102 are superimposed, whereby the transverse waves generated by the piezoelectric resonance layer 1051 are blocked in all directions by the top electrode projection portion 1081 presenting a closed annular shape.

2A-2C, in these embodiments of the present invention, the bottom electrode bridge portion 1040 is electrically connected to at least one side or at least one corner of the bottom electrode resonant portion 1041, After passing above the cavity (that is, 102B) floating outside the bottom electrode resonance part 1041 from the corresponding side of the bottom electrode resonance part 1041, part of the etching protection layer 101 on the outer periphery of the cavity 102 is etched. The top electrode bridge portion 1080 is electrically connected to at least one side or at least one corner of the top electrode protruding portion 1081 facing away from the top electrode resonance portion 1082, and the After passing above the cavity (that is, 102B) floating outside the top electrode protrusion 1081 from the top electrode protrusion 1081, it extends to above a part of the etching protection layer 101 on the outer periphery of the cavity 102. , and 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 just be connected or separated from each other, thereby allowing the top electrode The bridge portion 1080 and the bottom electrode bridge portion 1040 are offset from each other in the region of the cavity 102 without overlapping. For example, as shown in FIGS. 1A and 2A-2B, the bottom electrode bridge portion 1040 extends above a portion of the substrate at the perimeter of only one side of the cavity 102 to provide the top electrode bridge. A portion 1080 extends above a portion of the substrate at the perimeter of only one side of the cavity 102 , and at the bottom surface of the cavity 102 between the top electrode bridge portion 1080 and the bottom electrode bridge portion 1040 . are separated from each other, thereby avoiding the introduction of parasitic parameters and problems such as leaks and shorts that can be caused when the top electrode bridge portion 1080 and the bottom electrode bridge portion 1040 overlap. However, preferably, referring to FIG. 2C, the bottom electrode bridge portion 1040 is provided along all sides of the bottom electrode resonance portion 1041 and continuously extends to the substrate at the outer periphery of the cavity 102. , which allows the bottom electrode bridge portion 1040 to extend above some substrates in more directions at the perimeter of the cavity 102, i.e., when the bottom electrode bridge The portion 1040 completely covers the cavity 102 over the part of the cavity in which it is located, so that the laying of the large area bottom electrode bridge portion 1040 provides the effective working area 102A with a supporting force to the membrane layer. to prevent the cavity 102 from collapsing. More preferably, when the bottom electrode bridge portion 1040 extends above a portion of the substrate in more directions at the outer periphery of the cavity 102, the top electrode bridge portion 1080 extends from the outer periphery of the cavity 102. For example, if the top surface shape of the cavity 102 is rectangular, the top electrode bridge portion 1080 extends to the outer periphery of only one side of the cavity 102. , and the bottom electrode bridge portion 1040 extends to the other three sides of the cavity 102, where the top electrode bridge portion 1080 and the bottom electrode bridge portion 1040 and are just connected or separated from each other, i.e., the bottom electrode bridge portion 1040 is then above the portion of the cavity in which it is located. , completely covers the cavity 102 and does not overlap the top electrode bridge portion 1080 in the width direction of the top electrode bridge portion 1080 . Thus, when the top electrode bridge portion 1080 is provided in a large area, it vertically overlaps structures such as the bottom electrode bridge portion 1040, thereby avoiding introducing too many parasitic parameters and improving the electrical performance and reliability of the device. can be further improved.

In each embodiment of the present invention, when the top 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, thereby: At least one end of each of the bottom electrode resonance portion 1041 to which the bottom electrode bridge portion 1040 is connected and the top electrode resonance portion 1082 to which the top electrode projection portion 1081 is connected is completely floating. It contributes to the reduction of the area, and also reduces the parasitic parameters such as the parasitic capacitance generated in the invalid area 102B, thereby improving the performance of the device. Preferably, the top electrode protrusion 1081 is offset from at least the bottom electrode bridge portion 1040 above the cavity 102 (i.e., they do not overlap in the cavity area), thereby reducing the parasitic Further reduce parasitic parameters such as capacitors to improve device performance.

In order to realize the optimum transverse wave blocking effect and contribute to the fabrication of small-sized devices, it is preferable that the top electrode protrusion 1081 is closer to the effective operating area 102A, and the line width of the top electrode protrusion 1081 is smaller. More preferably, the line width of the top electrode protrusion 1081 is the minimum line width allowed for the corresponding process, and the top electrode protrusion 1081 and the effective operating area 102A (that is, the piezoelectric resonance layer 1051) is the minimum distance allowed for the corresponding process.

In each of the above embodiments, the top electrode resonance portion 1082 and the bottom electrode resonance portion 1041 have similar or the same shape and have the same area, or the area of the bottom electrode resonance portion 1041 is the same as that of the top electrode. Although the area of the resonator 1082 is larger, the technical solution of the present invention is not limited to this. In other embodiments of the present invention, the shape of the top electrode resonant portion 1082 and the bottom electrode resonant portion 1041 may not be similar, but the shape of the top electrode protruding portion 1081 may match the shape of the piezoelectric resonant layer 1051 . It is preferable that it matches and can extend along at least one side of the piezoelectric resonance layer 1051 . Furthermore, research has found that most of the parasitic transverse waves in bulk acoustic wave resonators are transmitted through the connecting structure between the film layers on the effective working area 102A and the substrate at the periphery of the cavity, thus , in each embodiment of the present invention, the area (i.e., line width) of the top electrode bridge portion 1080 is minimized, and the area (i.e., line width) of the bottom electrode bridge portion 1040 is minimized, provided that the membrane layers of the effective active area 102A can be effectively supported. The area (ie line width) can be controlled as much as possible.

An embodiment of the invention further provides a filter comprising at least one bulk acoustic wave resonator as described in any of the embodiments of the invention above.

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

Referring to FIG. 3, one embodiment of the present invention is a method of manufacturing a bulk acoustic wave resonator of the present invention (eg, the bulk acoustic wave resonator shown in FIGS. 1A-2C) comprising:
Step S1 of providing a substrate and forming a first sacrificial layer with a flat top surface on a portion of said substrate;
step S2 of forming a bottom electrode layer on a portion of the first sacrificial layer, the portion positioned on the top surface of the first sacrificial layer extending flatly;
a step S3 of forming a piezoelectric resonance layer on the bottom electrode layer and exposing a portion of the first sacrificial layer and a portion of the bottom electrode layer from the piezoelectric resonance layer;
step S4 of forming a second sacrificial layer having a sacrificial protrusion in a region exposed from the periphery of the piezoelectric resonance layer;
forming a top electrode layer on the piezoelectric resonant layer and a second sacrificial layer on a portion of the periphery of the piezoelectric resonant layer, the portion of the top electrode layer covered by the sacrificial protrusion forming a top electrode protrusion; S5;
removing the second sacrificial layer with sacrificial protrusions and the first sacrificial layer and forming a cavity at the location of the second sacrificial layer with sacrificial protrusions and the first sacrificial layer, comprising: and step S6, wherein the top electrode protrusion is located in the cavity area at the outer circumference of the piezoelectric resonance layer and extends around the piezoelectric resonance layer in the peripheral direction.

1A, 1B and 4A-4B, in step S1 of the present embodiment, the first sacrificial layer is formed into a part of the substrate by etching the substrate to form grooves and filling the grooves with material. The specific realization process formed above includes the following.

First, referring 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 formed by any suitable process method, such as thermal treatment methods such as thermal oxidation, thermal nitridation, thermal oxynitridation, or deposition methods such as chemical vapor deposition, physical vapor deposition or atomic layer deposition. , may be formed on the base 100 . Moreover, the etching thickness of the protective layer 101 may be reasonably set according to the actual device process needs, and is not specifically limited here.

Subsequently, referring to FIGS. 1A, 1B and 4A, at least one 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, preferably using a dry etching process, the dry etching process being reactive ion etching (RIE), ion beam etching, plasma etching, or laser cutting. Including but not limited to: The depth and shape of the 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 groove 102' is rectangular. In embodiments, the cross-section of groove 102' may also be any other suitable shape, such as circular, elliptical, or other polygonal shapes other than rectangular (pentagons, hexagons, etc.).

1A, 1B and 4B, a first sacrificial layer 103 may be filled into the trench 102' by a process such as vapor deposition, thermal oxidation, spin coating or epitaxial growth, and 1 sacrificial layer 103 may be selected semiconductor material, dielectric material or photoresist material different from the base 100 and etching protection layer 101, for example, if the base 100 is Si-based, the first sacrificial layer 103 may be Ge, in which case the formed first sacrificial layer 103 is further covered by the etching protection layer 101 at the periphery of the trench or the top surface is etched around the trench. by planarizing the top of the first sacrificial layer 103 to the top surface of the etching protection layer 101 by a chemical mechanical planarization (CMP) process, which may be higher than the top surface of the protection layer 101 . , the first sacrificial layer 103 is positioned only in the groove 102', and the top surface of the first sacrificial layer 103 is made flush with the top surface of the surrounding etching protection layer 101, thereby flattening. It provides a flat process surface for subsequent formation of the bottom electrode layer 104 with a surface.

Referring to FIGS. 1A, 1B and 4C, in step S2, first, an appropriate method is selected according to the material of the bottom electrode to be formed in advance, and the surfaces of the etching protection layer 101 and the first sacrificial layer 103 are etched. A bottom electrode material layer (not shown) may be coated, for example by physical vapor deposition such as magnetron sputtering, evaporation, or chemical vapor deposition methods to form the bottom electrode material layer and then the bottom electrode. A photoresist layer (not shown) in which a pattern is defined is formed on the bottom electrode material layer by a lithographic process, and the bottom electrode material layer is etched using the photoresist layer as a mask to form the bottom electrode layer (i.e., the bottom electrode layer). The remaining bottom electrode material layer) 104 is formed, after which the photoresist layer is removed. The bottom electrode material layer can use any suitable conductive or semiconductor material known in the art, and the conductive material can be a metallic material having electrical conductivity, such as aluminum ( Al), copper (Cu), platinum (Pt), gold (Au), molybdenum (Mo), tungsten (W), iridium (Ir), osmium (Os), rhenium (Re), palladium (Pd), rhodium ( Rh) and ruthenium (Ru), and the semiconductor material is, for example, Si, Ge, SiGe, SiC, SiGeC, or the like. In this embodiment, the bottom electrode layer (remaining bottom electrode material layer) 104 includes a bottom electrode resonance portion 1041 covered by an effective operating region 102A to be formed later, and a first electrode layer from one side of the bottom electrode resonance portion 1041 . Both the bottom electrode bridge portion 1040 and the bottom electrode resonance portion 1041 extending to a part of the etching protection layer 101 outside the groove 102' via the surface of the sacrificial layer 103 are separated. The outer peripheral portion 1042 of the bottom electrode serves as one metal contact of the bulk acoustic wave resonator to be formed in the region, and the bottom electrode resonant portion 1041 of the bottom electrode bridge portion 1040 and the back of the bottom electrode. 1040 as part of the bottom electrode bridge portion of an adjacent bulk acoustic wave resonator, and in other embodiments of the invention, the bottom electrode bridge portion 1040 The electrode perimeter 1042 may be omitted. The shape of the top surface of the bottom electrode resonance part 1041 may be a pentagon, and in another embodiment of the present invention, it may be a square or a hexagon. from the corresponding side of the bottom electrode resonance portion 1041 via the top surface of the first sacrificial layer 103 outside the bottom electrode resonance portion 1041 After that, it extends to the top surface of part of the etching protection layer 101 on the outer periphery of the groove 102'. Further, in this embodiment, since the top surface of the first sacrificial layer 103 and the top surface of the etching protection layer 101 are flush with each other, the bottom surface of the bottom electrode layer 104 to be formed is flush with the top surface. can also be made flush, at which time the bottom electrode layer 104 extends flat over the entire range, that is, the bottom electrode resonance part 1041 and the bottom electrode bridge part 1040 are made flush. It has a bottom surface and a flush top surface. Preferably, as shown in FIG. 2C, the bottom electrode bridge portion 1040 completely covers the cavity 102 above the portion of the cavity in which it is located, and across the width of the top electrode bridge portion 1080: The non-overlapping of the top electrode bridge portion 1080 improves the supporting capacity for subsequent membrane layers, and the overlap of the top electrode bridge portion 1080 avoids introducing unnecessary parasitic parameters as much as possible. The bottom electrode resonator 1041 may be used as an input electrode to receive or provide an electrical signal, such as a radio frequency (RF) signal, or as an output electrode.

1A, 1B and 4C, in step S3, first, piezoelectric material layer 105 is deposited by any suitable method known to those skilled in the art, such as chemical vapor deposition, physical vapor deposition, or atomic layer deposition. Alternatively, a photoresist layer (not shown) having a piezoelectric thin film pattern defined thereon 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. is etched to form the piezoelectric resonance layer 1051, after which the photoresist layer is removed. Materials of the piezoelectric material layer 105 are aluminum nitride (AlN), zinc oxide (ZnO), lead zirconate titanate (PZT), lithium niobate (LiNbO ₃ ), quartz, and potassium niobate (KNbO ₃ ). Alternatively, piezoelectric materials having a wurtzite crystal structure, such as lithium tantalate (LiTaO ₃ ), and combinations thereof may be used. The piezoelectric material layer 105 includes aluminum nitride (AlN) and may also include rare earth metals, such as at least one of scandium (Sc), erbium (Er), yttrium (Y), and lanthanum (La). Seeds. In addition, the piezoelectric material layer 105 contains aluminum nitride (AlN) and transition metal (eg, at least one of zirconium (Zr), titanium (Ti), manganese (Mn), and hafnium (Hf)). may include After patterning, the remaining piezoelectric material layer 105 includes a piezoelectric resonant layer 1051 and a piezoelectric outer peripheral portion 1050 that are separated from each other, the piezoelectric resonant layer 1051 being positioned on the bottom electrode resonant portion 1041 and the bottom electrode bridge portion 1040 . is exposed and may be completely or partially covered by the bottom electrode resonator 1041 . The shape of the piezoelectric resonance layer 1051 may be the same as or different from the shape of the bottom electrode resonance portion 1041, and the shape of the upper surface thereof may be a pentagon, a quadrangle, a hexagon, a heptagon, or Other polygons such as octagons are also possible. By forming a gap between the piezoelectric outer peripheral portion 1050 and the piezoelectric resonance layer 1051, a part of the first sacrificial layer 103 above the bottom electrode bridge portion 1040 and around the bottom electrode resonance portion 1041 is exposed, The gap that is formed limits the formation area of the subsequent second sacrificial layer and also provides a flat process surface for the subsequent formation of the sacrificial protrusions, and the piezoelectric perimeter 1050 is the top electrode that is subsequently formed. and the previously formed bottom electrode perimeter 1042, and provide a flat process surface for the subsequent formation of the second sacrificial layer and the top electrode layer. can be done.

Referring to FIGS. 1A, 1B and 4D, in step S4, first, the piezoelectric outer peripheral portion 1050, the piezoelectric resonant layer 1051, and the piezoelectric outer peripheral portion 1050 and the piezoelectric resonant layer are subjected to a suitable process such as a coating process or a vapor deposition process. 1051 may be coated with a second sacrificial layer 106, and the second sacrificial layer 106 can fill the gap between the piezoelectric outer peripheral portion 1050 and the piezoelectric resonance layer 1051, The material of the second sacrificial layer 106 can be amorphous carbon, photoresist, dielectric material (e.g. silicon nitride, silicon oxycarbide, porous material, etc.), or semiconductor material (e.g. polycrystalline silicon, amorphous silicon, germanium ), etc. Then, the second sacrificial layer 106 is formed into the piezoelectric outer peripheral portion 1050 by planarizing the top of the second sacrificial layer 106 by a CMP process. Only the gap between the piezoelectric resonance layer 1051 is filled, and the piezoelectric outer peripheral portion 1050, the piezoelectric resonance layer 1051 and the second sacrificial layer 106 form a flat upper surface. In another embodiment of the present invention, the second sacrificial layer 106 on the top surface of the piezoelectric outer periphery 1050 and the piezoelectric resonant layer 1051 is removed by an etch back process, thereby removing the piezoelectric outer periphery 1050 and the piezoelectric resonant layer 1051 . Only the interstices may be filled. A sacrificial material (not shown) may then be coated on the piezoelectric perimeter 1050, the piezoelectric resonant layer 1051 and the second sacrificial layer 106 by a suitable process such as a coating process or vapor deposition process, The thickness of the sacrificial material is determined by the protrusion height of the sacrificial protrusions 107 to be formed, and the sacrificial material can be amorphous carbon, photoresist, dielectric materials (e.g., silicon nitride, silicon oxycarbide, porous materials, etc.). ), or at least one selected from semiconductor materials (e.g., polycrystalline silicon, amorphous silicon, germanium), etc., preferably the same as the material of the second sacrificial layer 106, to save costs and process and then pattern the sacrificial material to form sacrificial protrusions 107 by a lithographic process or a combination of photo-etching and etching processes. The shape, size, position, etc. of the top electrode protrusion to be formed are determined. Preferably, the sidewalls of the sacrificial protrusion 107 are inclined with respect to the plane on which the piezoelectric resonance layer 1051 is located (that is, the top surface of the piezoelectric resonance layer 1051), so that the sidewalls of the sacrificial protrusion 107 and the top of the piezoelectric resonance layer 1051 are inclined. The angles θ1 and θ2 between the surfaces are both 45 degrees or less, which contributes to coating the top electrode recess 1081 with material later, avoids cutting, and ensures thickness uniformity. Improve. More preferably, the line width of the sacrificial protrusion 107 is the minimum line width allowed for the corresponding process, and the horizontal distance between the sacrificial protrusion 107 and the piezoelectric resonance layer 1051 (the sacrificial protrusion 107 and the piezoelectric resonance layer 1051 ) is the minimum distance allowed for the corresponding process, thereby achieving favorable shear wave blocking effect and contributing to device size reduction. In other embodiments of the present invention, the sacrificial protrusion 107 and the second sacrificial layer 106 may be formed by the same process, for example, first the piezoelectric outer periphery 1050, the piezoelectric resonant layer 1051, and the piezoelectric outer periphery 1050 and the piezoelectric resonant layer. The gap between the layer 1051 is covered with a second sacrificial layer 106 having a thickness equal to or greater than the sum of the thickness of the piezoelectric resonance layer 1051 and the thickness of the sacrificial protrusion 107, and then the second sacrificial layer is formed by an etching process. 106 is patterned to form the second sacrificial layer 106 that fills only the gap between the piezoelectric outer peripheral portion 1050 and the piezoelectric resonance layer 1051 , and part of the second sacrificial layer 106 is the sacrificial protrusion 107 , the bottom surface of the sacrificial protrusion 107 and the top surface of the piezoelectric resonance layer 1051 may be flush with each other, and the top surface of the remaining part of the second sacrificial layer 106 and the top surface of the piezoelectric resonance layer 1051 may be flush with each other. It is flush with the top surface.

1A, 1B and 4E, in step S5, first, based on the material of the pre-formed top electrode, select an appropriate method, and A top electrode material layer (not shown) may be coated on the surfaces of the sacrificial layer 106 and the sacrificial protrusions 107, for example, by physical vapor deposition, such as magnetron sputtering deposition, or chemical vapor deposition methods. Layers may be formed, the top electrode material layer may be uniform in thickness at each location, and then a photoresist layer (not shown) having a top electrode pattern defined thereon is deposited by a lithographic process. A top electrode layer (i.e., the patterned top electrode material layer or the remaining top electrode material layer) 108 is formed on the electrode material layer and etched by etching the top electrode material layer using the photoresist layer as a mask. is formed, after which the photoresist layer is removed. The top electrode material layer may use any suitable conductive or semiconducting material known in the art, and the conductive material may be a metallic material having electrical conductivity, such as Al, Cu, Pt, Au, Mo, W, Ir, Os, Re, Pd, Rh and Ru, etc., and the semiconductor material is, for example, Si, Ge, SiGe, SiC, SiGeC, etc. is. In this embodiment, the top electrode layer 108 includes a top electrode resonant portion 1082 coated on the piezoelectric resonant layer 1051 , a top electrode protrusion 1081 coated on the sacrificial protrusion 107 , and a top electrode protrusion 1081 . A top electrode bridge portion 1080 extending through the top surface of the second sacrificial layer 106 of the second sacrificial layer 106 and onto the piezoelectric outer peripheral portion 1050 outside the top electrode projection portion 1081, a top electrode resonance portion 1082 and a top electrode It includes a protrusion 1081 and a top electrode perimeter 1083 which are both separated, the top electrode perimeter 1083 serving as one metal contact of the bulk acoustic wave resonator to be formed in the region, the top electrode bridge portion. 1080 may be connected to one side facing away from the top electrode resonator portion 1082, or may be separated from the top electrode bridge portion 1080 as part of the top electrode bridge portion of the adjacent bulk acoustic wave resonator. In other embodiments of the invention, the top electrode perimeter 1083 may be omitted. The shape of the top surface of the top electrode resonance part 1082 may be the same as or different from the shape of the piezoelectric resonance layer 1051. The shape of the top surface is, for example, a pentagon. The area of the top electrode resonator 1082 is preferably larger than the piezoelectric resonator layer 1051 so as to be completely sandwiched between the electrode resonator 1041, thereby contributing to the reduction of device size and parasitic parameters. In other embodiments of the present invention, the shape of the top electrode resonator 1082 may also be polygonal, such as square, hexagon, heptagon, or octagon. The top electrode layer 108 may be used as an input electrode for receiving or providing electrical signals, such as radio frequency (RF) signals, or as an output electrode. For example, when bottom electrode layer 104 is used as an input electrode, top electrode layer 108 may be used as an output electrode, and when bottom electrode layer 104 is used as an output electrode, top electrode layer 108 may be used as an input electrode. The piezoelectric resonance layer 1051 converts an electrical signal input via the top electrode resonance section 1082 or the bottom electrode resonance section 1041 into a bulk acoustic wave. For example, the piezoelectric resonant layer 1051 converts electrical signals into bulk acoustic waves by physical vibration. The top electrode projecting portion 1081 is provided along at least one side of the top electrode resonant portion 1082 and connected to the corresponding side of the top electrode resonant portion 1082. It is provided along the side of the top electrode resonant portion 1082 and is provided at least in a region where the top electrode bridge portion 1080 and the top electrode resonant portion 1082 are aligned. A closed ring structure is formed around the entire circumference of the electrode resonant portion 1082 (shown in FIGS. 2B and 2C), and for example, the top electrode protrusion 1081 extends at a plurality of continuous sides of the top electrode resonant portion 1082. This constitutes an open ring structure (shown in FIG. 2A). The top electrode bridge portion 1080 is electrically connected to the side of the top electrode protruding portion 1081 facing away from the top electrode resonant portion 1082. From above the top electrode protruding portion 1081, a part of the second sacrificial layer 106 to the top surface of a portion of the etching protection layer 101 outside the groove 102', and the top electrode bridge portion 1080 and the bottom electrode bridge portion 1040 are connected to each other. At least one side of the groove 102' is exposed from each of the top electrode bridge portion 1080 and the bottom electrode bridge portion 1040, with offset (ie, they do not overlap in the region of the cavity 102). In one embodiment of the present invention, referring to FIGS. 1A and 2A, at least from the projection of the top electrode protrusion 1081 in the projection on the bottom surface of the groove 102′, the bottom electrode of the bottom electrode resonator 1041 A projection of the boundary connected by the bridge portion 1040 is exposed. The projections of the top electrode bridge portion 1080 and the bottom electrode bridge portion 1040 on the bottom surface of the groove 102' are just connected or separated from each other, and the top electrode bridge portion 1080 is connected to the groove 102. ' may extend above a portion of the substrate at the perimeter of only one side of '.

Referring to FIGS. 1A, 1B and 4F, in step S6, a photo-etching and etching process, or a combined process with laser ablation, is applied to the edge of the piezoelectric perimeter 1050 facing the groove 102′ or the bulk acoustic wave resonance. A hole may be drilled around the device region of the device, and at least one of a portion of the first sacrificial layer 103, a portion of the sacrificial protrusion 107, or the second sacrificial layer 106 exposed from the sacrificial protrusion 107. by forming an open hole (not shown) capable of exposing the sacrificial protrusion 107, the second sacrificial layer 106, and the first sacrificial layer 103 and re-emptying the second groove to form a cavity 102, which consists of the space of the groove 102' and the space increased by the top electrode protrusion 1081. , and the space originally occupied by the second sacrificial layer 106 below the top electrode protrusion 1081 . The bottom electrode resonance part 1041, the piezoelectric resonance layer 1051, and the top electrode resonance part 1082, which float above the cavity 102 and are stacked in order, constitute an independent bulk acoustic thin film. The portion where the top electrode resonator 1082 and the cavity 102 overlap each other along the vertical direction is the effective area, defined as the effective actuation area 102A, which allows electrical energy, such as radio frequency signals, to pass through the bottom electrode. When the voltage is applied to the resonance part 1041 and the top electrode resonance part 1082 , due to the piezoelectric phenomenon occurring in the piezoelectric resonance layer 1051 , vibration and resonance occur in the thickness direction (that is, the longitudinal direction) of the piezoelectric resonance layer 1051 , and the cavity 102 The other area of is the ineffective area 102B, which is an area 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 floating above the effective operating area 102A and composed of the bottom electrode resonance part 1041, the piezoelectric resonance layer 1051 and the top electrode resonance part 1082, which are stacked in order, corresponds to the vibration of the piezoelectric phenomenon of the piezoelectric resonance layer 1051. can output a radio frequency signal with a resonance frequency that Specifically, when electrical energy is applied to the top electrode resonance portion 1082 and the bottom electrode resonance portion 1041, the piezoelectric phenomenon occurring in the piezoelectric resonance layer 1051 generates bulk acoustic waves. In this case, the bulk acoustic waves produced are not only the desired longitudinal waves, but also parasitic transverse waves, which are intercepted by the top electrode protrusion 1081, confined to the effective active area 102A, and propagated to the membrane layers at the outer periphery of the cavity. , thereby improving the acoustic wave loss due to the propagation of transverse waves to the film layers at the periphery of the cavity, thereby improving the quality factor of the resonator and ultimately improving the performance of the device. be able to.

It should be noted that step S6 may be performed after all membrane layers above the cavity 102 to be formed have been fabricated, thereby subsequently forming the first sacrificial layer 103 and the second sacrificial layer 106. can be used to protect the space where the cavity 102 is located and the film layer structure stacked with the bottom electrode layer 104 to the top electrode layer 108 formed thereon, and after the cavity 102 is formed, subsequent To avoid the risk of cavity collapse caused when performing the process of Also, the open hole formed in step S6 may be left so that subsequent packaging processes such as bonding two substrates can seal the open hole and also seal the cavity 102 .

In step S1 of the method for manufacturing the bulk acoustic wave resonator of each of the above embodiments, the first sacrificial layer 103 is partially removed by etching the substrate to form the groove 102' and filling the groove 102'. , the cavity 102 formed in step S6 has a groove structure whose entire bottom is recessed into the substrate, but the technical solution of the present invention is not limited to this. In step S1 of another embodiment of the present invention, by further forming a first sacrificial layer 103 protruding entirely above the substrate by a combined process of film layer deposition and photo-etching and etching, step S6 2D and 5, in step S1, a groove 102 for fabricating the cavity 102 is formed in a cavity structure protruding from the substrate surface as a whole. ' is first coated on the etching protection layer 101 on the surface of the base 100 with a first sacrificial layer 103, and then by a combined photoetching and etching process, the first sacrificial layer 103 is formed. is patterned to leave only the first sacrificial layer 103 covered on the region 102, and further the first sacrificial layer 103 is formed on a part of the substrate, the first sacrificial layer 103 is formed from top to bottom. The top surface of the first sacrificial layer 103 is flat, and the thickness of the first sacrificial layer 103 determines the depth of the cavity 102 to be formed later. In this embodiment, the corresponding sidewalls of the bottom electrode perimeter 1042, the bottom electrode bridge 1040, the piezoelectric perimeter 1050, the top electrode perimeter 1083, and the top electrode bridge 1080 are formed as protruding first sacrificial layers. 103, and the vertical cross-section must all be a "Z"-shaped structure, and the subsequent steps are the manufacturing method of the bulk acoustic wave resonator of the embodiment shown in FIGS. 4A-4F. are exactly the same as their counterparts in , and will not be described in detail here. At this time, the portion of the bottom electrode layer 104 located above the cavity 102 extends flatly, that is, the portion above the cavity of the bottom electrode bridge portion 1040 (the portion corresponding to the side wall of the first sacrificial layer 103). ) and the top surface of the bottom electrode resonance portion 1041 are flush with each other, and above the cavity of the bottom electrode bridge portion 1040 (not including the portion corresponding to the side wall of the first sacrificial layer 103). and the bottom surface of the bottom electrode resonance portion 1041 are flush with each other.

Preferably, in the bulk acoustic wave resonator of the present invention, the bottom electrode bridge portion, the top electrode protruding portion and the bottom electrode resonator portion are manufactured in the same process by using the manufacturing method of the bulk acoustic wave resonator of the present invention, The top electrode bridge portion, the top electrode projection portion and the top electrode resonance portion are manufactured by the same process, further simplifying the process and reducing the manufacturing cost.

Of course, those skilled in the art can make various changes and modifications to this invention without departing from the spirit and scope of this invention. Thus, it is intended that the present invention include these modifications and variations of the present invention as they fall within the scope of the claims of the present invention and their equivalents.

100 base 101 etch protection layer 102 cavity 102' groove 102A active active area 102B inactive area 103 first sacrificial layer 104 bottom electrode layer (ie, remaining bottom electrode material layer)
1040 Bottom electrode bridge portion 1041 Bottom electrode resonance portion 1042 Bottom electrode outer peripheral portion 105 Piezoelectric material layer 1050 Piezoelectric outer peripheral portion 1051 Piezoelectric resonance layer (or referred to as piezoelectric resonance portion)
106 second sacrificial layer 107 sacrificial protrusion 108 top electrode layer (i.e. remaining top electrode material layer)
1080 top electrode bridge portion 1081 top electrode protrusion portion 1082 top electrode resonance portion 1083 top electrode outer peripheral portion

Claims (16)

A bulk acoustic wave resonator,
a substrate;
A bottom electrode layer provided on the substrate, wherein a cavity is formed between the bottom electrode layer and the substrate, and a portion of the bottom electrode layer located above the cavity extends flat. a bottom electrode layer;
a piezoelectric resonance layer formed on the bottom electrode layer in an upper portion of the cavity;
A top electrode layer formed on the piezoelectric resonance layer, the top electrode layer being positioned above the cavity on the outer periphery of the piezoelectric resonance layer, protruding away from the bottom surface of the cavity, and a top electrode layer having a top electrode protrusion extending in a peripheral direction surrounding the layer ;
a piezoelectric outer peripheral portion provided between the bottom electrode layer and the top electrode layer so as to be separated from the piezoelectric resonant layer and positioned on the outer periphery of the piezoelectric resonant layer;
the top electrode projecting portion is positioned between the piezoelectric resonance layer and the piezoelectric outer peripheral portion in plan view,
The bottom electrode layer is
a bottom electrode resonance portion overlapping the piezoelectric resonance layer in the stacking direction;
a bottom electrode bridge connected to the bottom electrode resonator and extending below the piezoelectric perimeter so as to float above the cavity;
The top electrode layer is
a top electrode resonance part overlapping the piezoelectric resonance layer in the stacking direction;
a top electrode bridge connected to the top electrode resonator and extending above the piezoelectric perimeter to float above the cavity;
A bulk acoustic wave resonator characterized by: 2. The bulk acoustic wave resonator according to claim 1 , wherein both said bottom electrode resonator and said top electrode resonator are polygonal. The top electrode projecting portion is provided along a side of the top electrode resonant portion and is provided at least in a region where the top electrode bridge portion and the top electrode resonant portion are aligned. Item 3. The bulk acoustic wave resonator according to item 2. The top electrode protrusion is displaced from at least the bottom electrode bridge above the cavity, or the top electrode protrusion surrounds the top electrode resonance section. 4. The bulk acoustic wave resonator according to claim 3 . the bottom electrode bridge portion and the bottom electrode resonance portion are formed of the same film layer,
2. The bulk acoustic wave resonator according to claim 1 , wherein said top electrode protrusion, said top electrode bridge and said top electrode resonator are formed of the same film layer. The bottom electrode bridge part covers the cavity above a part of the cavity where the bottom electrode bridge part is located, and does not overlap the top electrode bridge part in the width direction of the top electrode bridge part. 3. A bulk acoustic wave resonator according to claim 2 . sidewalls of the top electrode projecting portion are inclined with respect to the top surface of the piezoelectric resonance layer;
7. The bulk acoustic wave resonator according to any one of claims 1 to 6 , wherein an angle between the side wall of the top electrode protrusion and the top surface of the piezoelectric resonance layer is 45 degrees or less. . 7. The cavity according to any one of claims 1 to 6 , wherein the cavity has a groove structure in which the entire bottom is recessed in the substrate, or a cavity structure in which the entire protrusion is provided on the surface of the substrate. A bulk acoustic wave resonator as described. A filter comprising the bulk acoustic wave resonator according to any one of claims 1 to 8 . A radio frequency communication system comprising a filter according to claim 9 . A method of manufacturing a bulk acoustic wave resonator, comprising:
providing a substrate and forming a first sacrificial layer having a flat top surface on a portion of the substrate;
forming a bottom electrode layer on a portion of the first sacrificial layer, the portion located on the top surface of the first sacrificial layer extending flatly;
forming a piezoelectric resonance layer on the bottom electrode layer exposing a portion of the first sacrificial layer and a portion of the bottom electrode layer;
forming a second sacrificial layer having a sacrificial protrusion on a portion of the first sacrificial layer exposed around the piezoelectric resonance layer;
A top electrode layer is formed on the piezoelectric resonance layer and a portion of the second sacrificial layer surrounding the piezoelectric resonance layer, and a portion of the top electrode layer covering the sacrificial protrusion is formed as a top electrode protrusion. a step;
removing the second sacrificial layer and the first sacrificial layer with the sacrificial protrusion and forming a cavity at the location of the second sacrificial layer and the first sacrificial layer with the sacrificial protrusion; wherein the top electrode protrusion is located above the cavity at the outer periphery of the piezoelectric resonance layer and extends in a peripheral direction surrounding the piezoelectric resonance layer;
The bulk acoustic wave resonator includes a piezoelectric outer peripheral portion provided between the bottom electrode layer and the top electrode layer so as to be separated from the piezoelectric resonant layer and positioned on the outer periphery of the piezoelectric resonant layer,
the top electrode projecting portion is positioned between the piezoelectric resonance layer and the piezoelectric outer peripheral portion in plan view,
The bottom electrode layer is
a bottom electrode resonance portion overlapping the piezoelectric resonance layer in the stacking direction;
a bottom electrode bridge connected to the bottom electrode resonator and extending below the piezoelectric perimeter so as to float above the cavity;
The top electrode layer is
a top electrode resonance part overlapping the piezoelectric resonance layer in the stacking direction;
a top electrode bridge connected to the top electrode resonator and extending above the piezoelectric perimeter to float above the cavity;
A method of manufacturing a bulk acoustic wave resonator, characterized by: Forming the first sacrificial layer with a flat top surface on a portion of the substrate comprises etching the substrate to form a second groove in the substrate; forming a layer to fill the second trench to planarize the top surface of the first sacrificial layer; or
Forming the first sacrificial layer on a portion of the substrate comprises coating the first sacrificial layer on the substrate to planarize a top surface of the first sacrificial layer; patterning one sacrificial layer to form the first sacrificial layer to protrude above a portion of the substrate. A method for manufacturing a wave resonator. removing the second sacrificial layer and the first sacrificial layer having the sacrificial protrusions,
at least one opening exposing at least part of the first sacrificial layer, part of the sacrificial protrusions, or part of the second sacrificial layer other than the sacrificial protrusions after forming a top electrode layer; forming a hole;
and removing the second sacrificial layer having the sacrificial protrusions and the first sacrificial layer by introducing a gas and/or a chemical solution into the open holes. 3. A method for manufacturing a bulk acoustic wave resonator according to . Forming the bottom electrode layer comprises:
depositing a bottom electrode material layer overlying the first sacrificial layer and the substrate at the perimeter of the first sacrificial layer; patterning the bottom electrode material layer to in turn connect bottoms; forming an electrode bridge portion and a bottom electrode resonance portion, wherein the bottom electrode resonance portion and the piezoelectric resonance layer overlap each other, one end of the bottom electrode bridge portion abuts the substrate on the outer periphery of the cavity, and the Bulk acoustic wave resonance according to claim 11 , characterized in that the top surface of the portion of the bottom electrode bridge portion located above the cavity and the bottom electrode resonating portion are made flush with each other. The method of making the vessel. Forming the top electrode layer comprises:
depositing a top electrode material layer overlying the second sacrificial layer having the sacrificial protrusions and the piezoelectric resonance layer; and patterning the top electrode material layer to form connected top electrode bridges in turn. a step of forming a section, the top electrode projecting section, and a top electrode resonance section, wherein the top electrode resonance section and the piezoelectric resonance layer overlap, and one end of the top electrode bridge section extends from the substrate at the outer circumference of the cavity. 5. The method of manufacturing a bulk acoustic wave resonator according to claim 1 , wherein the top electrode bridge portion and the bottom electrode bridge portion extend upward and are offset from each other. . Both the bottom electrode resonance portion and the top electrode resonance portion are polygonal,
The top electrode projecting portion is provided along a side of the top electrode resonant portion and is provided at least in a region where the top electrode bridge portion and the top electrode resonant portion are aligned. Item 15. A method for manufacturing a bulk acoustic wave resonator according to Item 15 .

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