WO2013102342A1

WO2013102342A1 - Film bulk acoustic resonator, communication device and radio frequency module

Info

Publication number: WO2013102342A1
Application number: PCT/CN2012/078036
Authority: WO
Inventors: 王建; 张宗民
Original assignee: 华为技术有限公司
Priority date: 2012-01-04
Filing date: 2012-07-02
Publication date: 2013-07-11
Also published as: CN102545827A; CN102545827B

Abstract

Provided are a film bulk acoustic resonator (FBAR), communication device and radio frequency module, the FBAR comprising a substrate, and the substrate having a lower electrode layer, a piezoelectric film and an upper electrode layer sequentially disposed thereon; the substrate and the lower electrode layer are laminated with two or more air gaps therebetween. The FBAR provided in an embodiment of the present invention has higher power capacity, stable structure and smaller size, and is suitable for applications requiring high power capacity.

Description

Film bulk acoustic resonator, communication device and RF module

TECHNICAL FIELD Embodiments of the present invention relate to resonator technology, and more particularly to a film bulk acoustic resonator, a communication device, and a radio frequency module. Background technique

With the development of wireless communication technology, integration and miniaturization have become the development trend of wireless RF modules. The integration, miniaturization and high power of the filters in the front-end circuits of RF modules have become critical. Since the Film Bulk Acoustic Resonator (FBAR) has the advantages of small volume, high operating frequency and easy integration, filters composed of film bulk acoustic resonators have been widely used in the field of wireless communication devices.

Figure 1 is a schematic view showing the structure of a conventional air gap structure FBAR. As shown in FIG. 1, in the existing air gap structure FBAR, in the piezoelectric sandwich structure composed of the upper electrode 101, the piezoelectric film 102, and the lower electrode 103, the piezoelectric sandwich structure is disposed on the substrate 104, and An air gap 105 is formed on the substrate 104. When the FBAR is in operation, the FBAR can be acoustically isolated by the air gap 105 to ensure the performance of the FBAR. Since FBAR relies on the up and down vibration of the piezoelectric sandwich structure, during the FBAR operation, stress concentration occurs at the edge of the air gap (as shown by the dotted line in Figure 1), and the power is increased with the operation of the FBAR. The stronger the vibration of the piezoelectric film, the greater the stress generated at the stress concentration. When the stress generated exceeds the stress-bearing strength of the lower electrode, the piezoelectric film and the upper electrode, the piezoelectric sandwich structure of the FBAR is caused. If collapsed or broken, FBAR will not work properly. In addition, in the prior art, the power capacity of the FBAR is generally increased by increasing the area of the air gap in the FBAR structure, but after the air gap area in the FBAR is increased to a certain extent, the FBAR structure will become more unstable, and the power capacity of the FBAR instead There will be no increase, and there will be a tendency for stress to drop.

In summary, in the existing air gap structure FBAR, due to the stress concentration problem at the air gap edge, the power capacity of the FBAR is limited, and the FBAR power capacity is low; and simply by increasing the area of the air gap in the FBAR structure, the air gap area After reaching a certain level, the FBAR structure will become more unstable, and the power capacity of the FBAR will not increase, but the power capacity will decrease. SUMMARY OF THE INVENTION Embodiments of the present invention provide a film bulk acoustic resonator, a communication device, and a radio frequency module, which can effectively overcome the problem that the air gap stress existing in the existing FBAR structure is too large, resulting in a low power capacity, and can improve the film body. Based on the power capacity of the acoustic resonator, the stress concentration problem is reduced.

An embodiment of the present invention provides a film bulk acoustic resonator, comprising: a substrate on which a lower electrode layer, a piezoelectric film, and an upper electrode layer are sequentially stacked;

Two or more air gaps are provided between the substrate and the lower electrode layer.

The embodiment of the invention provides a communication device, which comprises the film bulk acoustic resonator provided by the embodiment of the invention.

The embodiment of the present invention provides a radio frequency module, including a duplexer or a multiplexer, wherein the resonator in the duplexer or the multiplexer is the film bulk acoustic resonator provided by the embodiment of the present invention. Provided by a film bulk acoustic resonator, a communication device and a radio frequency module, the film bulk acoustic resonator has a plurality of air gap structures, and each air gap shares the same upper electrode layer, piezoelectric film and lower electrode layer, thus, the film body acoustic wave When the resonator is working, the vibration generated by the piezoelectric film is dispersed on the air gap structure, so that the stress generated at the edge of each air gap structure is small, which can effectively improve the stability of the entire acoustic bulk acoustic resonator structure. Reliability; At the same time, since each air gap shares the upper electrode layer and the piezoelectric film lower electrode layer, the power of the film bulk acoustic resonator is the sum of the powers generated by the piezoelectric film regions corresponding to the air gaps, so that the film bulk acoustic resonator The whole body can have a higher power capacity, and it can meet the high power demand of the film bulk acoustic wave resonator application; The power circuit has the same power capacity, the present embodiment provides a thin film bulk acoustic resonator having a smaller volume and structural stability. DRAWINGS

The drawings used in the embodiments or the description of the prior art are briefly described. It is obvious that the drawings in the following description are some embodiments of the present invention, and are not creative to those skilled in the art. Other drawings can also be obtained from these drawings on the premise of labor.

1 is a schematic structural view of a conventional air gap structure FBAR; 2A is a schematic structural view of a film bulk acoustic resonator according to Embodiment 1 of the present invention; FIG. 2B is a schematic structural view of an air gap shown by AA in FIG. 2A;

FIG. 3 is a schematic structural diagram of an air gap in a film bulk acoustic resonator according to Embodiment 2 of the present invention; FIG.

4 is a schematic structural view of a film bulk acoustic wave resonator according to Embodiment 3 of the present invention;

5A is a schematic structural diagram of a radio frequency module according to Embodiment 4 of the present invention;

Figure 5B is a schematic view showing the structure of the duplexer of Figure 5A. The technical solutions in the embodiments of the present invention will be clearly and completely described in the following with reference to the accompanying drawings in the embodiments of the present invention. Examples are some embodiments of the invention, and not all of the embodiments. All other embodiments obtained by a person of ordinary skill in the art based on the embodiments of the present invention without creative efforts are within the scope of the present invention.

2A is a schematic structural view of a film bulk acoustic resonator according to Embodiment 1 of the present invention; and FIG. 2B is a schematic structural view of an air gap shown by A-A in FIG. 2A. As shown in FIG. 2A, the FBAR of the present embodiment includes a substrate 11 on which a lower electrode layer 12, a piezoelectric film 13 and an upper electrode layer 14 are sequentially laminated; between the substrate 11 and the lower electrode layer 12 Two or more air gaps 15 are also provided. In the FBAR structure provided by the embodiment, the plurality of air gaps share the upper electrode layer and the lower electrode layer. When the FBAR is in operation, the piezoelectric film generates vibrations at the respective air gaps, thereby dispersing the stress generated by the vibration of the piezoelectric film to At the edge of each air gap, the stress generated at the edge of each air gap will be very small, which can effectively improve the stability of the entire FBAR structure; at the same time, multiple air gaps share the electrode layer, and the overall area of the air gap can be made. Larger, allowing FBAR to operate in higher power environments, effectively increasing the power capacity of FBAR.

In the present embodiment, as shown in Figs. 2A and 2B, a plurality of barriers 151 may be disposed on the substrate 11, so that the air gaps 15 may be formed by the plurality of barriers 151. In practical applications, a barrier of a suitable width can be provided as needed, for example, the barrier width can be set to be between 1/3 and 2 times the thickness of the piezoelectric film, so that the formed FABR is operated at the edge of the air gap. It can have better stress tolerance and increase the stability and reliability of the FBAR structure.

In this embodiment, as shown in FIG. 2A, a lower electrode layer 12 and each air gap 15 are further disposed. A support layer 16 is provided to enhance the stability of the entire FBAR structure by the support layer 16, increase the mechanical strength at the edges of the air gap 15, and improve the stress tolerance at the edges of the air gaps 15.

In this embodiment, the air gap 15 formed on the substrate 11 may have a square structure, for example, a square or rectangular structure. Specifically, as shown in FIG. 2B, each air gap 15 in this embodiment has a rectangular structure, and the width to length ratio of the rectangular structure may be between 1:1-1:1.5.

In this embodiment, via holes may be disposed between the air gaps 15 formed on the substrate 11, and specifically, as shown in FIG. 2B, the barriers 151 between the adjacent air gaps 15 may be opened. There is a via 152, such that the adjacent two air gaps 15 are turned on, so that during the FBAR fabrication process, the etching gas or liquid can be easily flowed between the air gaps in the etching process, wherein the via holes 152 can be in the middle of the barrier 151, and the width of the via can be 1/5-1/3 of the length of the barrier, avoiding excessive via size and affecting the performance of the FBAR.

It will be understood by those skilled in the art that the above-described arrangement of the lower electrode layer 12, the piezoelectric film 13 and the upper electrode layer 14 on the substrate 11 means that the surface of the substrate 11 is arranged in the direction perpendicular to the surface. The lower electrode layer 12, the piezoelectric film 13, and the upper electrode layer 14.

Those skilled in the art can understand that the FBAR provided in this embodiment can be equivalent to a plurality of conventional FBARs in parallel in circuit function. Therefore, the FBAR of the present embodiment can have the power capacity of the traditional FBAR cost, so that the FBAR capacity is greatly improved; In the FBAR structure provided by the embodiment, the plurality of air gaps share the upper electrode layer, the piezoelectric film and the lower electrode layer, so that the FBAR structure is stable, and the power capacity of the plurality of conventional FBARs is achieved. In this case, it is possible to have a smaller volume, so that the communication device using the FBAR of the present embodiment can have a smaller volume and a higher power capacity.

The film bulk acoustic resonator provided in this embodiment has a plurality of air gap structures, and each air gap shares the same upper electrode layer, piezoelectric film and lower electrode layer, so that when the FBAR is operated, the vibration generated by the piezoelectric film is Disperse into each air gap structure, so that the stress generated at the edge of each air gap structure is small, which can effectively improve the stability and reliability of the entire FBAR structure; at the same time, the upper electrode layer and the piezoelectric film are shared by the air gaps. In the lower electrode layer, the power of the FBAR is the sum of the power generated by the piezoelectric film regions corresponding to the air gaps, so that the FBAR as a whole can have a higher power capacity and meet the high power requirement of the FBAR application.

3 is a schematic structural view of an air gap in a film bulk acoustic wave resonator according to Embodiment 2 of the present invention. Different from the technical solutions of the embodiment shown in FIG. 2A and FIG. 2B above, the shape of this embodiment is The air gap formed on the substrate may be a polygonal structure, for example, a pentagonal shape, a hexagonal shape, or a regular polygonal structure. Specifically, as shown in FIG. 3, the air gap 15 in this embodiment is Hexagonal structure.

4 is a schematic structural view of a film bulk acoustic wave resonator according to Embodiment 3 of the present invention. Different from the technical solution of the embodiment shown in FIG. 2A, the air gap in this embodiment may be a groove structure disposed on the substrate. Specifically, as shown in FIG. 4, two substrates are opened on the substrate 11 or More than two groove structures that form an air gap 15.

By forming a groove on the substrate to form a desired air gap, it can effectively improve

The convenience of FBAR production reduces production costs.

It can be understood by those skilled in the art that in the above embodiments of the present invention, the structure of the air gap can be other irregular structures, such as square, polygonal, etc., in practical applications, the air gap can also be set to other irregularities as needed. A shape, or a combination of a plurality of shapes, is not limited in this embodiment of the present invention.

The embodiment of the present invention further provides a communication device, which may include the FBAR provided by the embodiment of the present invention. Specifically, the communication device may be a filter, a duplexer or an oscillator, and the FBAR provided by the above invention may be used. It is connected by series connection, parallel connection, or by series connection and parallel connection. Since the FBAR constituting the communication device has a higher power capacity, the number of resonators in the communication device can be reduced correspondingly, and the power capacity of the communication device can be improved. Meanwhile, in the communication device of the embodiment, the FBAR can be equivalent to the conventional device. A plurality of parallel FBARs can reduce the volume of the entire communication device on the basis of having a plurality of conventional parallel FBAR power capacities.

In the embodiment of the present invention, a radio frequency module is further provided, and the radio frequency module includes a duplexer or a multiplexer, and the resonator in the duplexer or the multiplexer is the FB AR provided by the embodiment of the present invention. The technical solution of the embodiment of the present invention will be described below by taking a radio frequency module in a radio communication base station as an example.

5A is a schematic structural diagram of a radio frequency module according to Embodiment 4 of the present invention; and FIG. 5B is a schematic structural diagram of the duplexer of FIG. 5A. The radio frequency module in this embodiment can be applied to a wireless base station of a third generation mobile communication technology (3rd-generation, 3G) and a long term evolution (LTE), and can meet the high power requirement of the wireless base station, and can have more The small volume, specifically, as shown in FIG. 5A, the radio frequency module of this embodiment may include a duplexer 10, and the duplexer 10 The radio frequency receiving circuit 20, the radio frequency transmitting circuit 30 and the antenna 40 are respectively connected. When receiving the signal, the signal received from the antenna 40 can be processed by the duplexer 10 and the radio frequency receiving circuit 20, and then transmitted to the corresponding base station signal processor; When the signal is transmitted, the signal sent by the base station signal processing unit can be transmitted from the antenna 40 after being processed by the radio frequency transmitting circuit 30 and the duplexer 10.

In this embodiment, as shown in FIG. 5A, the radio frequency receiving circuit 20 may include a receiving end attenuator 201, a signal suppressing filter 202, and a low noise amplifier 203, which are sequentially electrically connected, and the low noise amplifier 203 and the duplexer 10 The receiving end attenuator 201 is connected to the signal processor in the base station; the radio frequency transmitting circuit 30 may include a transmitting end attenuator 301, a first power amplifier 302 and a second power amplifier 303, which are sequentially electrically connected, and the second power amplifier 303 and The duplexer 10 is connected, and the transmitter attenuator 301 is connected to a signal processor in the base station. The radio frequency receiving circuit and the radio frequency transmitting circuit in this embodiment may have the same or similar structure as the radio frequency module in the conventional base station, and the embodiment of the present invention is not limited.

In this embodiment, the resonator in the duplexer 10 described above can use the FBAR provided by the above embodiment of the present invention. As shown in FIG. 5B, the duplexer 10 is composed of a transmit link 110, a receive link 120, an antenna terminal 130, and a quarter transmission line 140, wherein the transmit link 110 and the receive link 120 are both The FBAR 140 provided by the embodiment of the invention is connected in series and in parallel. In practical applications, each FBAR can be constructed as a T-type, Ji-type, r-type or network cross-type structure circuit as needed to achieve the required band pass or band stop characteristics. It can be understood by those skilled in the art that the duplexer in this embodiment can be in the form of a conventional circuit structure, except that the resonator therein uses the FBAR provided by the above embodiment of the present invention; The FBARs are formed in parallel, so that the FBARs provided in this embodiment can replace the plurality of FBARs connected in parallel in the conventional circuit as needed, and can have the same power and be smaller in size.

It should be noted that the above embodiments are merely illustrative of the technical solutions of the present invention, and are not intended to be limiting; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art The technical solutions described in the foregoing embodiments may be modified, or some or all of the technical features may be equivalently replaced; and the modifications or substitutions do not deviate from the technical solutions of the embodiments of the present invention. range.

Claims

I. A film bulk acoustic wave resonator, comprising: a substrate on which a lower electrode layer, a piezoelectric film and an upper electrode layer are sequentially stacked;

2. The film bulk acoustic resonator according to claim 1, wherein a plurality of barriers are disposed between the substrate and the lower electrode layer, and the plurality of barriers are enclosed to form the air gaps. .

The film bulk acoustic resonator according to claim 1, wherein the substrate is provided with two or more groove structures, and the groove structure forms the air gap.

The film bulk acoustic resonator according to claim 2 or 3, wherein a through hole is provided between the air gaps.

The film bulk acoustic resonator according to claim 1, 2 or 3, wherein the air gap has a polygonal structure.

The film bulk acoustic resonator according to claim 5, wherein the air gap has a regular polygonal structure.

The film bulk acoustic resonator according to claim 1, 2 or 3, wherein the air gap has a square structure.

The film bulk acoustic resonator according to claim 7, wherein the air gap is a rectangular structure having a width to length ratio of 1:1 to 1:5.

The film bulk acoustic resonator according to claim 1, 2 or 3, wherein a support layer is further disposed between the lower electrode layer and each air gap.

A communication device comprising the film bulk acoustic resonator according to any one of claims 1 to 9.

I I. The communication device according to claim 10, wherein the communication device is a filter, a duplexer or an oscillator.

12. A radio frequency module, comprising a duplexer or a multiplexer, wherein the resonator in the duplexer or multiplexer is a film bulk acoustic wave according to any one of claims 1-9. Resonator.