CN116614096A - Resonator and preparation method and application thereof - Google Patents

Resonator and preparation method and application thereof Download PDF

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Publication number
CN116614096A
CN116614096A CN202310560475.5A CN202310560475A CN116614096A CN 116614096 A CN116614096 A CN 116614096A CN 202310560475 A CN202310560475 A CN 202310560475A CN 116614096 A CN116614096 A CN 116614096A
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China
Prior art keywords
electrode
extraction electrode
extraction
resonator
carrier
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Inventor
杨清华
赖志国
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Suzhou Huntersun Electronics Co Ltd
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Suzhou Huntersun Electronics Co Ltd
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Priority to CN202310560475.5A priority Critical patent/CN116614096A/en
Publication of CN116614096A publication Critical patent/CN116614096A/en
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    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
    • H03H3/00—Apparatus or processes specially adapted for the manufacture of impedance networks, resonating circuits, resonators
    • H03H3/007—Apparatus or processes specially adapted for the manufacture of impedance networks, resonating circuits, resonators for the manufacture of electromechanical resonators or networks
    • H03H3/02—Apparatus or processes specially adapted for the manufacture of impedance networks, resonating circuits, resonators for the manufacture of electromechanical resonators or networks for the manufacture of piezoelectric or electrostrictive resonators or networks
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
    • H03H9/00—Networks comprising electromechanical or electro-acoustic devices; Electromechanical resonators
    • H03H9/02—Details
    • H03H9/02007—Details of bulk acoustic wave devices
    • H03H9/02015—Characteristics of piezoelectric layers, e.g. cutting angles
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
    • H03H9/00—Networks comprising electromechanical or electro-acoustic devices; Electromechanical resonators
    • H03H9/02—Details
    • H03H9/125—Driving means, e.g. electrodes, coils
    • H03H9/13—Driving means, e.g. electrodes, coils for networks consisting of piezoelectric or electrostrictive materials
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
    • H03H3/00—Apparatus or processes specially adapted for the manufacture of impedance networks, resonating circuits, resonators
    • H03H3/007—Apparatus or processes specially adapted for the manufacture of impedance networks, resonating circuits, resonators for the manufacture of electromechanical resonators or networks
    • H03H3/02—Apparatus or processes specially adapted for the manufacture of impedance networks, resonating circuits, resonators for the manufacture of electromechanical resonators or networks for the manufacture of piezoelectric or electrostrictive resonators or networks
    • H03H2003/023—Apparatus or processes specially adapted for the manufacture of impedance networks, resonating circuits, resonators for the manufacture of electromechanical resonators or networks for the manufacture of piezoelectric or electrostrictive resonators or networks the resonators or networks being of the membrane type

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  • Physics & Mathematics (AREA)
  • Acoustics & Sound (AREA)
  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Piezo-Electric Or Mechanical Vibrators, Or Delay Or Filter Circuits (AREA)

Abstract

The present disclosure provides a resonator, a method of manufacturing the resonator, and applications thereof, wherein the method of manufacturing the resonator includes: providing a carrier; forming an acoustic reflecting structure on the carrier; simultaneously forming a lower electrode, a first extraction electrode and a second extraction electrode on the acoustic reflection structure; forming a piezoelectric layer on the lower electrode; the first extraction electrode and the second extraction electrode are physically isolated from the piezoelectric layer; the first extraction electrode is physically isolated from the lower electrode.

Description

Resonator and preparation method and application thereof
Technical Field
The present disclosure relates to the field of electronics, and in particular, to a resonator, and a method of manufacturing and application thereof.
Background
With the popularization of the fourth-generation mobile communication technology (4G) and the popularization of the fifth-generation mobile communication technology (5G) trial operation, the performance requirements for the radio frequency filter become more stringent. The FBAR filter has the advantages of small size, high resonant frequency, high quality factor, large power capacity, good roll-off effect and the like, so that the FBAR filter occupies a larger share in the field of radio frequency front ends, particularly in the market of radio frequency filters. The film bulk acoustic resonator of the prior art is a fundamental component of an FBAR filter.
Referring to fig. 1, fig. 1 is a schematic structural diagram of a conventional film bulk acoustic resonator with a cavity. As shown in fig. 1, the thin film bulk acoustic resonator includes a carrier 100, a cavity 101 formed in the carrier 100, the cavity 101 constituting an acoustic reflection region of the bulk acoustic resonator.
The thin film bulk acoustic resonator further has a functional structural layer covering the upper surface of the carrier 100, where the functional structural layer includes a lower electrode 103, an upper electrode 105, and a piezoelectric layer 104 sandwiched between the upper and lower electrodes (i.e., the lower electrode and the upper electrode), where the upper and lower electrodes and the piezoelectric layer form a "sandwich" structure. An alternating current signal is applied between the electrodes, an input electric signal is converted into sound wave vibration by using an inverse piezoelectric effect, and then the sound wave vibration is converted into an electric signal by using the piezoelectric effect to be output.
Various different types of radio frequency filters can be constructed by various different cascading modes between the plurality of thin film bulk acoustic resonator units. The thin film bulk acoustic resonator unit may be composed of one or more thin film bulk acoustic resonators. Furthermore, the radio frequency filters with different frequencies can form radio frequency devices such as a duplexer, a multiplexer and the like through mutual connection.
Referring to fig. 2, fig. 2 is a block diagram showing a circuit structure of a WCDMA duplexer in the prior art.
As shown in fig. 2, the duplexer includes a transmit filter TX connected between the common port ANT and the transmit port TXP, and a receive filter RX connected between the common port ANT and the receive port RXP. The common port is an external port that transmits and receives electric waves through an antenna. The transmitting filter TX has a plurality of series branches and parallel branches, each of which includes a thin film bulk acoustic resonator unit 1, and the thin film bulk acoustic resonator unit 1 may be formed of a single or a plurality of thin film bulk acoustic resonators connected in series, in parallel, or in series-parallel. The receiving filter RX has a plurality of series branches and parallel branches, each of which includes a thin film bulk acoustic resonator unit 2, and the thin film bulk acoustic resonator unit 2 may be formed of a single or a plurality of thin film bulk acoustic resonators connected in series, in parallel, or in series-parallel.
Referring to fig. 3 a-3 b, fig. 3 a-3 b show chip layout diagrams of filters in the WCDMA duplexer shown in fig. 2. FIG. 3a shows a chip layout of a receive filter in the duplexer shown in FIG. 2; fig. 3b shows a chip layout design of the transmit filter in the diplexer shown in fig. 2.
As shown in fig. 3a, the reception filter RX has a lower electrode lead-out electrode 10 connected to the lower electrode of the thin film bulk acoustic resonator 1 therein, and an upper electrode lead-out electrode 20 connected to the upper electrode of the thin film bulk acoustic resonator therein.
As shown in fig. 3b, the transmitting filter TX has a lower electrode lead-out electrode 30 connected to the lower electrode of the thin film bulk acoustic resonator 2 therein, and an upper electrode lead-out electrode 40 connected to the upper electrode of the thin film bulk acoustic resonator therein.
The lower electrode and the lower electrode lead-out electrodes (10, 30) of the thin film bulk acoustic resonator in the transmitting filter TX or the receiving filter RX are usually formed simultaneously in the manufacturing process. The lower electrode and the lower electrode lead-out electrodes (10, 30) are manufactured, and the upper electrode lead-out electrodes (20, 40) can be manufactured by a peeling (liftoff) process. Specifically, a seed layer may be deposited, photoresist is coated, photoresist is removed from a portion of the region, thereby exposing the seed layer in the corresponding region, metal is deposited over the entire surface, then the photoresist and the metal deposited thereon are stripped, and the lower and lower electrode lead-out electrodes (10, 30) and the upper electrode lead-out electrodes (20, 40) are fabricated at the corresponding regions where the seed layer is exposed.
Referring to fig. 4, fig. 4 is a physical diagram of the lower electrode lead-out electrodes (10, 30) and the upper electrode lead-out electrodes (20, 40) of the film bulk acoustic resonator. As shown in fig. 4, the lower electrode lead-out electrodes (10, 30) are likely to be empty compared to the upper electrode lead-out electrodes (20, 40), so that the lower electrode lead-out electrodes (10, 30) are separated from the carrier, or the seed layer (when the seed layer exists) below the lower electrode lead-out electrodes (10, 30) is separated from the carrier, thereby affecting the reliability of the device and reducing the yield of the device.
Therefore, it is desirable to provide a thin film bulk acoustic resonator structure and a method for fabricating the same to solve the above-mentioned problems, thereby improving the reliability and product performance of the device.
Disclosure of Invention
The present disclosure is directed to the above-mentioned technical problems, and designs a thin film bulk acoustic resonator structure and a method for manufacturing the same, which can reduce the defects of a lower electrode extraction electrode and improve the product performance and reliability of the thin film bulk acoustic resonator.
A brief summary of the disclosure will be presented below in order to provide a basic understanding of some aspects of the disclosure. It should be understood that this summary is not an exhaustive overview of the disclosure. It is not intended to identify key or critical elements of the disclosure or to delineate the scope of the disclosure. Its purpose is to present some concepts in a simplified form as a prelude to the more detailed description that is discussed later.
According to an aspect of the present disclosure, there is provided a method of manufacturing a resonator, including: providing a carrier; forming an acoustic reflecting structure on the carrier; simultaneously forming a lower electrode, a first extraction electrode and a second extraction electrode on the acoustic reflection structure; forming a piezoelectric layer on the lower electrode;
the first extraction electrode and the second extraction electrode are physically isolated from the piezoelectric layer; the first extraction electrode is physically isolated from the lower electrode.
Further, a first fracture is formed between the first extraction electrode and the lower electrode.
Further, there is no overlap between the projection of the piezoelectric layer on the first surface and the projection of the first extraction electrode and/or the second extraction electrode on the first surface.
Further, forming an upper electrode on the piezoelectric layer is also included.
Further, the projection pattern of the upper electrode on the first surface and the projection pattern of the second extraction electrode on the first surface have a second fracture.
Further, the projection pattern of the upper electrode on the first surface and the projection pattern of the second extraction electrode on the first surface do not have a second fracture.
Further, a first connection electrode is formed to electrically connect the first extraction electrode and the lower electrode.
Further, the first connection electrode is formed at the first break.
Further, a second connection electrode is formed to electrically connect the second extraction electrode and the lower electrode, and the second connection electrode is formed at the second fracture.
Further, a second connection electrode is formed to electrically connect the second extraction electrode and the lower electrode.
Further, a step of forming a seed layer is further included between the lower electrode, the first extraction electrode, and the second extraction electrode and the carrier.
According to another aspect of the present disclosure there is provided a resonator comprising: a carrier having opposed first and second surfaces; an acoustic reflecting structure disposed on the first surface; the lower electrode, the first extraction electrode and the second extraction electrode are arranged on the carrier in a coplanar manner; a piezoelectric layer disposed on the lower electrode; the first extraction electrode and the second extraction electrode are physically isolated from the piezoelectric layer; the first extraction electrode is physically isolated from the lower electrode.
Further, the first extraction electrode and the lower electrode are physically isolated through a first fracture.
Further, there is no overlap between the projection of the piezoelectric layer on the first surface and the projection of the first extraction electrode and/or the second extraction electrode on the first surface.
Further, the device further comprises the first connecting electrode, wherein the first extraction electrode is electrically connected with the lower electrode through the first connecting electrode.
Further, the first connection electrode is disposed at the first fracture.
Further, the first discontinuity has a width greater than 0.5 microns.
Further, the piezoelectric device further comprises an upper electrode and a second connecting electrode, wherein the upper electrode is formed on the piezoelectric layer, and the upper electrode is electrically connected with the second extraction electrode through the second connecting electrode.
Further, the second extraction electrode has a second fracture between the projection pattern of the first surface and the projection pattern of the upper electrode on the first surface.
Further, the second connection electrode is disposed at the second fracture.
Further, the second extraction electrode does not have a second fracture between the projection pattern of the first surface and the projection pattern of the upper electrode on the first surface.
Further, a seed layer is further provided between the lower electrode, the first extraction electrode, and the second extraction electrode and the carrier.
According to yet another aspect of the present disclosure there is provided a radio frequency device comprising a resonator network of a plurality of resonators, the resonators being the resonators of the foregoing.
According to yet another aspect of the present disclosure, there is provided an electronic device including the radio frequency device in the foregoing.
The solution of the present disclosure can at least help to achieve one of the following effects: the empty defect at the leading-out electrode of the lower electrode of the film bulk acoustic resonator is avoided, the reliability of the electric connection and test of the film bulk acoustic resonator is improved, and the yield and the performance of the device are improved.
Drawings
The above and other objects, features and advantages of the present disclosure will be more readily appreciated by reference to the following description of the specific details of the disclosure taken in conjunction with the accompanying drawings. The drawings are only for the purpose of illustrating the principles of the present disclosure. The dimensions and relative positioning of the elements in the figures are not necessarily drawn to scale.
FIG. 1 is a schematic diagram of a conventional film bulk acoustic resonator with a cavity;
fig. 2 is a block diagram showing a circuit structure of a WCDMA duplexer in the related art;
fig. 3 a-3 b show chip layout diagrams of filters in the WCDMA duplexer shown in fig. 2;
FIG. 4 is a physical diagram of a lower electrode lead-out electrode and an upper electrode lead-out electrode of a film bulk acoustic resonator;
FIG. 5a shows a top view of a structure of a thin film bulk acoustic resonator in accordance with an embodiment of the present disclosure;
FIG. 5b shows a cross-sectional view of the structure of the thin film bulk acoustic resonator at A-A in FIG. 5 a;
FIG. 5c is a top view showing the structure of a thin film bulk acoustic resonator according to an embodiment of the present disclosure when no connection electrode is formed;
FIG. 6a is a top view of a structure of a thin film bulk acoustic resonator of a comparative example;
FIG. 6b shows a partial cross-sectional view of the thin film bulk acoustic resonator at A '-A' in FIG. 6 a;
fig. 7 shows a flow chart of one fabrication of a thin film bulk acoustic resonator of the present disclosure.
Detailed Description
Exemplary disclosure of the present disclosure will be described hereinafter with reference to the accompanying drawings. In the interest of clarity and conciseness, not all features of an implementation of the present disclosure are described in the specification. It will be appreciated, however, that in the development of any such actual implementation, numerous implementation-specific decisions may be made to achieve the developers' specific goals, and that these decisions may vary from one implementation to another.
Here, it is also to be noted that, in order to avoid obscuring the present disclosure with unnecessary details, only device structures closely related to the scheme according to the present disclosure are shown in the drawings, while other details not greatly related to the present disclosure are omitted.
It is to be understood that the present disclosure is not limited to the described embodiments due to the following description with reference to the drawings. Herein, features between different embodiments may be substituted or borrowed where possible, and one or more features may be omitted in one embodiment. It should be understood that the manufacturing steps of the present disclosure are exemplary in embodiments, and that the order of the steps may be varied.
In this embodiment, a thin film bulk acoustic resonator is taken as an example, and a structure and a manufacturing method thereof will be described. It will be understood by those skilled in the art that the technical solution of the present embodiment is not limited to the thin film bulk acoustic resonator, and the solution can be applied as long as the carrier has various devices of upper and lower electrodes and piezoelectric layers forming a "sandwich" structure.
< embodiment 1 >
Referring to fig. 5a to 5c, fig. 5a is a top view showing a structure of a thin film bulk acoustic resonator according to a first embodiment of the present disclosure, fig. 5b is a cross-sectional view showing a structure of the thin film bulk acoustic resonator according to A-A in fig. 5a, and fig. 5c is a top view showing a structure of the thin film bulk acoustic resonator according to a first embodiment of the present disclosure when no connection electrode is formed, wherein like reference numerals refer to like parts.
As shown in fig. 5a-5c, the thin film bulk acoustic resonator includes: a carrier 1000, a functional stack assembly 2000, a first extraction electrode 3000, a second extraction electrode 4000, a first connection electrode 5000, and a second connection electrode 6000.
Specifically, an acoustic reflection region 1100 is formed in the carrier 1000 of the thin film bulk acoustic resonator; those skilled in the art will appreciate that carrier 1000 may illustratively be comprised of a substrate, which may be, for example, silicon (Si), gallium arsenide (GaAs), indium phosphide (InP), glass, sapphire, alumina, siC, etc., materials compatible with semiconductor processes; alternatively, the carrier 1000 may be a composite member formed of a substrate with a dielectric layer (not shown), which may be a single layer or multiple layers, and the dielectric layer may be made of silicon dioxide (SiO 2 ) Silicon nitride (Si) 3 N 4 ) Silicon dioxide/silicon nitride/silicon dioxide (ONO), aluminum oxide (Al 2 O 3 ) And the like.
Further, the acoustic reflection region 1100 may be formed by etching a cavity on the carrier 1000. When carrier 1000 is a composite layer of a substrate and a dielectric layer, cavity 1100 may be formed in the substrate alone, in the dielectric layer, or in both the substrate and the dielectric layer.
The acoustic reflection region 1100 may be formed by etching a cavity on the carrier 1000, and filling the cavity with a bragg reflection layer formed by stacking a high acoustic impedance layer and a low acoustic impedance layer in order. The high acoustic impedance layer can be tungsten, gold, platinum, diamond, silicon carbide and other materials with high density and high rigidity coefficient, and the low acoustic impedance layer can be silicon dioxide, polysilicon, polyimide, cyclooctene and other materials with low density and low rigidity coefficient.
A seed layer 1110 may be formed on the carrier 1000, and the material of the seed layer 1110 may be aluminum nitride (AlN), doped aluminum nitride, or the like, which is beneficial for subsequent lower electrode deposition. Then, a lower electrode 1200, a first extraction electrode 3000, and a second extraction electrode 4000 are deposited on the seed layer 1110.
The lower electrode 1200 may be a single layer or a plurality of layers, and the lower electrode 1200 may be formed of one or more conductive materials, for example, a metal material having high acoustic impedance and high acoustic velocity compatible with semiconductor processes, including tungsten (W), molybdenum (Mo), iridium (Ir), aluminum (Al), platinum (Pt), ruthenium (Ru), niobium (Nb), or hafnium (Hf), etc.
The first extraction electrode 3000 and the second extraction electrode 4000 may have the same layer structure as the lower electrode 1200. A first break 3100 is provided between the first extraction electrode 3000 and the lower electrode 1200, and the width of the first break is greater than 0.5um. The first extraction electrode 3000 and the lower electrode 1200 are electrically connected through the first connection electrode 5000, and illustratively, when the first extraction electrode 3000 is used for testing in the following, the first connection electrode 5000 is formed at the first break 3100 and covers the first extraction electrode 3000.
A piezoelectric layer 1300 is formed on the lower electrode 1200, and the piezoelectric layer 1300 may be formed of any piezoelectric material compatible with semiconductor processes, such as aluminum nitride (AlN), doped aluminum nitride, or titanate zirconate (PZT). Wherein, the projection of the piezoelectric layer 1300 on the upper surface of the carrier 1000 and the projection of the lower electrode 1200 on the upper surface of the carrier 1000 have overlapping portions, and the piezoelectric layer 1300 is physically isolated from the first extraction electrode 3000 and the second extraction electrode 4000. An example of physical isolation may be that the projection of the piezoelectric layer 1300 on the upper surface of the carrier 1000 does not overlap with the projection of the first extraction electrode 3000 and the second extraction electrode 4000 on the upper surface of the carrier 1000.
An upper electrode 1400 is formed on the piezoelectric layer 1300, and the upper electrode 1400 may be formed of one or more conductive materials, including, for example, various metals compatible with semiconductor processes, such as tungsten, molybdenum, iridium, aluminum, platinum, ruthenium, niobium, or hafnium. The materials of the upper electrode 1400 and the lower electrode 1200 may be the same or different. Among them, the lower electrode 1200, the piezoelectric layer 1300, and the upper electrode 1400 constitute a functional stack assembly 2000.
The second extraction electrode 4000 has a second break 4100 between the projected pattern of the upper surface of the carrier 1000 and the projected pattern of the upper electrode 1400 on the upper surface of the carrier 1000.
As will be appreciated by those skilled in the art, since the second extraction electrode 4000 and the lower electrode 1200 have the same layer structure and are spaced apart from each other at the same distance, the piezoelectric layer 1300 is physically isolated from the second extraction electrode 4000, and the second extraction electrode 4000 and the upper electrode 1400 are disposed in different spaces, the second break 4100 may not be provided between the projected pattern of the second extraction electrode 4000 on the upper surface of the carrier 1000 and the projected pattern of the upper electrode 1400 on the upper surface of the carrier 1000.
The second extraction electrode 4000 and the upper electrode 1400 are electrically connected through a second connection electrode 6000. When the second extraction electrode 4000 is used for testing in the following, the second connection electrode 6000 is formed at the second break 4100 and covers the second extraction electrode 4000.
The first extraction electrode 3000 and the second extraction electrode 4000 in this disclosure may be test electrodes for testing a thin film bulk acoustic resonator in device fabrication; the first extraction electrode 3000 and the second extraction electrode 4000 may also be signal transmission electrodes that serve as a cascade of a thin film bulk acoustic resonator with other thin film bulk acoustic resonators. That is, the first extraction electrode 3000 and the second extraction electrode 4000 may be any electrodes that are electrically connected to the functional stack 2000 in the thin film bulk acoustic resonator.
It can be understood that when the receiving filter and the transmitting filter are built by using the film bulk acoustic resonator of the present disclosure and the receiving filter and the transmitting filter are fabricated on the same chip to prepare a duplexer or a multiplexer and other radio frequency devices, the duplexer or the multiplexer may have a break at each of the extraction electrodes for extracting the electrical signal from the stacked structure of all the film bulk acoustic resonators, physically isolating the piezoelectric layer at the stacked structure from each of the extraction electrodes, and electrically connecting each of the extraction electrodes with the stacked structure of the film bulk acoustic resonator in the receiving filter and the transmitting filter by the connection electrode by setting the corresponding connection electrode at each of the break, so as to avoid hollowing at the extraction electrodes.
Referring to fig. 6a-6b, fig. 6a is a top view of a structure of a thin film bulk acoustic resonator according to a comparative example, and fig. 6b is a cross-sectional view of a portion of the structure of the thin film bulk acoustic resonator at a '-a' in fig. 6 a. Fig. 6a-6b differ from the first embodiment of the present disclosure in that: the first extraction electrode 3000 'is not provided with a first break and a first connection electrode between the first extraction electrode 3000' and the lower electrode, and the first extraction electrode 3000 'is directly and physically connected to the lower electrode 1200'. The second extraction electrode 4000' may have a second break or not between the projected pattern of the second extraction electrode 4000' on the upper surface of the carrier 1000' and the projected pattern of the upper electrode 1400' on the upper surface of the carrier 1000 '. It is understood that the second extraction electrode and the upper electrode 1400' may be electrically connected by the second connection electrode when the second break is provided.
After the fabrication of the upper electrode 1400' is completed, the thin film bulk acoustic resonator provided in the comparative example can be detected by detecting that the hollows as shown in fig. 4 are easily generated at the first extraction electrode, and the hollows are also hardly generated at the second extraction electrode.
Therefore, the structure of the film bulk acoustic resonator provided by the disclosure does not affect the signal input and output of the lower electrode 1200 or the upper electrode 1400, and the hollowness of the electrode is not generated at the first extraction electrode 3000, so that the defect generation at the first extraction electrode 3000 is reduced, the cascade connection and test reliability of the film bulk acoustic resonator are improved, and the product performance of the radio frequency device comprising the film bulk acoustic resonator is further improved.
Referring to fig. 7, fig. 7 shows a manufacturing flow chart of a thin film bulk acoustic resonator according to the present disclosure. The steps of fabricating the thin film bulk acoustic resonator of the present disclosure are further described with reference to fig. 7 and fig. 5a-5 c.
S100, providing a carrier
Illustratively, the carrier 1000 is a substrate, and the material of the substrate is selected as described above and will not be described in detail herein. The substrate mainly plays a role in supporting the device layer structure, and the Si substrate is taken as an example, so that the mechanical robustness is good, and the firmness and reliability in the processing and packaging processes can be ensured.
S200 forming an acoustic reflection region
The carrier 1000 is etched and a cavity 1100 is formed in the carrier 1000, the cavity 1100 being used to constitute an acoustic reflection region of the thin film bulk acoustic resonator. The cavity 1100 is filled with a sacrificial layer, the sacrificial layer is used for supporting the deposition of a subsequent device film on the substrate, the sacrificial layer can be selected from phosphosilicate glass, silicon dioxide, amorphous silicon and other film materials which can be compatible with the deposition temperature of the subsequent film, do not pollute a process system and have good etching selectivity and chemical polishing property. It will be appreciated by those skilled in the art that the support layer may also be formed on the substrate, the recess being formed by etching the support layer, the recess being filled with the sacrificial layer.
It will also be appreciated by those skilled in the art that the sacrificial layer may be replaced by a Bragg reflection layer formed by stacking a high acoustic impedance layer and a low acoustic impedance layer in this order.
S300 forming a lower electrode, a first extraction electrode and a second extraction electrode
A seed layer 1110 may be deposited on the carrier 1000, and the material of the seed layer 1110 is as described above and will not be described here. A layer of lower electrode material is then further deposited on the seed layer 1110. The material selection of the lower electrode material layer is as described above, and will not be described here again. The lower electrode material layer is patterned, and simultaneously the lower electrode 1200 and the first and second extraction electrodes 3000 and 4000 are formed. The lower electrode 1200 and the first extraction electrode 3000 are provided in the form of a first break 3100 during patterning.
S400 formation of piezoelectric layer
The deposition forms a piezoelectric layer material that is selected to meet the bandwidth requirements of the wireless mobile communication transceiver, preferably considering materials compatible with semiconductor processing such as aluminum nitride or titanate zirconate.
The piezoelectric layer material is patterned to form a piezoelectric layer 1300 over the lower electrode 1200. Illustratively, the projection of the piezoelectric layer 1300 on the upper surface of the carrier 1000 overlaps the projection of the lower electrode 1200 on the upper surface of the carrier 1000, while the projection of the piezoelectric layer 1300 on the upper surface of the carrier 1000 does not overlap the projections of the first extraction electrode 3000 and the second extraction electrode 4000 on the upper surface of the carrier 1000.
S500 forming upper electrode
A photoresist layer is deposited over the piezoelectric layer 1300, the photoresist is patterned, and a layer of upper electrode material is deposited, the materials of the upper electrode layer material layer being as described above. The upper electrode layer 1400 is formed through a lift-off process. It is understood that other process steps may be employed to form the upper electrode layer 1400, which is not further limited in this disclosure.
The second extraction electrode 4000 has a second break 4100 between the projected pattern of the upper surface of the carrier 1000 and the projected pattern of the upper electrode 1400 on the upper surface of the carrier 1000. It is understood that the second extraction electrode 4000 may not have the second break 4100 between the projection pattern of the upper surface of the carrier 1000 and the projection pattern of the upper electrode 1400 on the upper surface of the carrier 1000.
S600 forming first and second connection electrodes
The photoresist is coated, and a portion of the photoresist is removed, exposing a portion of the area, such as at the first and second breaks 3100 and 4100. A metal material is deposited, photoresist and the metal material thereon are removed, and a first connection electrode 5000 and a second connection electrode 6000 are formed at corresponding regions to achieve electrical connection between the lower electrode 1200 and the first extraction electrode 3000 and electrical connection between the upper electrode 1400 and the second extraction electrode 4000.
S700 other procedures
Other thin film bulk acoustic resonator fabrication processes are performed, illustratively, removal of the sacrificial layer, release of the cavity, and the like.
The reason why the empty bump does not occur at the first extraction electrode 3000 in the present disclosure is further described below by means of a process flow.
Since the piezoelectric layer is composed of a piezoelectric crystal, the atomic arrangement inside the piezoelectric crystal is asymmetric, and in general, positive and negative charges cancel each other, and the entire crystal is not charged. But the piezoelectric crystal is deformed when being stressed, the change of the interatomic distance disturbs the original balance to generate net charges, and positive charges or negative charges are generated on the surface of the piezoelectric crystal. The piezoelectric layer inevitably generates stress during the preparation of the thin film bulk acoustic resonator.
As described above, the first extraction electrode 3000 'of the thin film bulk acoustic resonator of the comparative example is directly and physically connected to the lower electrode 1200', and thus the first extraction electrode 3000 'is electrically connected to the piezoelectric layer 1300'. When the first extraction electrode 3000' is exposed in a process such as photolithography, charge in the piezoelectric layer 1300' is transferred to the first extraction electrode 3000' due to the electrical connection between the first extraction electrode 3000' and the piezoelectric layer 1300 '. The corresponding charges may charge ions in the plating solution, etching solution, or cleaning solution in a subsequent process such as electroplating or wet etching, wet cleaning, etc. Based on the piezoelectric effect, charged particles are caused to accumulate at the first extraction electrode 3000', which accelerates the reaction rate of the electroplating solution, etching solution, or cleaning solution with the first extraction electrode 3000' compared to when no charged particles accumulate; thus, the partial region of the first extraction electrode 3000 'is easily undercut seriously, and the partial region of the first extraction electrode 3000' is separated from the carrier 1000', so that the first extraction electrode 3000' forms a hollow in the partial region; when a seed layer is present between the first extraction electrode 3000' and the carrier 1000', the aggregation of charged particles accelerates the reaction rate of the plating solution, etching solution or cleaning solution with the seed layer compared to when the charged particles are not aggregated, and the seed layer is easily completely or partially undercut due to the thinner thickness of the seed layer, so that the seed layer is separated from the carrier 1000', and the first extraction electrode 3000' is adhered to the seed layer, so that a region corresponding to the first extraction electrode 3000' where the seed layer is completely or partially undercut forms a void.
In the present disclosure, by forming the first fracture between the first extraction electrode 3000 and the lower electrode 1200 and breaking the connection between the first extraction electrode 3000 and the piezoelectric layer 1300, the above situation is avoided, and thus, no empty drum is formed at the first extraction electrode 3000. In the present disclosure, since the second extraction electrode 4000 and the lower electrode 1200 have the same layer structure and are not disposed on the same layer as the upper electrode 1400, the second extraction electrode 4000 is physically isolated from the piezoelectric layer 1300, and thus, hollowness is not likely to occur at the second extraction electrode 4000.
The thin film bulk acoustic resonator disclosed in the present disclosure may be used for preparing radio frequency devices such as filters, diplexers, multiplexers, and the like, and further may be used in the fields of electronic devices such as mobile phones, personal digital assistants (Personal Digital Assistant, PDA), personal wearable devices, electronic game devices, and the like.
The present disclosure has been described in connection with specific embodiments, but it should be apparent to those skilled in the art that the description is intended to be illustrative and not limiting of the scope of the disclosure. Various modifications and alterations of this disclosure may be made by those skilled in the art in light of the spirit and principles of this disclosure, and such modifications and alterations are also within the scope of this disclosure.

Claims (24)

1. A method of manufacturing a resonator, comprising:
providing a carrier;
forming an acoustic reflecting structure on the carrier;
simultaneously forming a lower electrode, a first extraction electrode and a second extraction electrode on the acoustic reflection structure;
forming a piezoelectric layer on the lower electrode;
the first extraction electrode and the second extraction electrode are physically isolated from the piezoelectric layer;
the first extraction electrode is physically isolated from the lower electrode.
2. The method of manufacturing according to claim 1, wherein: a first fracture is formed between the first extraction electrode and the lower electrode.
3. The method of manufacturing as claimed in claim 2, wherein: there is no overlap between the projection of the piezoelectric layer on the first surface and the projection of the first extraction electrode and/or the second extraction electrode on the first surface.
4. A method of preparation as claimed in claim 2 or 3, wherein: further comprising forming an upper electrode on the piezoelectric layer.
5. The method of manufacturing according to claim 4, wherein: the projection pattern of the upper electrode on the first surface and the projection pattern of the second extraction electrode on the first surface are provided with a second fracture.
6. The method of manufacturing according to claim 4, wherein: the projection pattern of the upper electrode on the first surface and the projection pattern of the second extraction electrode on the first surface are not provided with second fractures.
7. The method of claim 5 or 6, wherein: a first connection electrode is formed to electrically connect the first extraction electrode and the lower electrode.
8. The method of manufacturing according to claim 7, wherein: the first connection electrode is formed at the first break.
9. The method of manufacturing according to claim 5, wherein: and forming a second connecting electrode to electrically connect the second extraction electrode and the lower electrode, wherein the second connecting electrode is formed at the second fracture.
10. The method of manufacturing according to claim 6, wherein: and forming a second connecting electrode to electrically connect the second extraction electrode and the lower electrode.
11. The method of any one of claims 1-3, 5-6, or 8-10, wherein: the method further includes the step of forming a seed layer between the lower electrode, the first extraction electrode, and the second extraction electrode and the carrier.
12. A resonator, comprising:
a carrier having opposed first and second surfaces;
an acoustic reflecting structure disposed on the first surface;
the lower electrode, the first extraction electrode and the second extraction electrode are arranged on the carrier in a coplanar manner;
a piezoelectric layer disposed on the lower electrode;
the first extraction electrode and the second extraction electrode are physically isolated from the piezoelectric layer;
the first extraction electrode is physically isolated from the lower electrode.
13. The resonator of claim 12, wherein the first extraction electrode is physically isolated from the lower electrode by a first break.
14. The resonator of claim 13, wherein there is no overlap between the projection of the piezoelectric layer on the first surface and the projection of the first extraction electrode and/or the second extraction electrode on the first surface.
15. The resonator of claim 14, wherein: the first lead-out electrode is electrically connected with the lower electrode through the first connecting electrode.
16. The resonator of claim 15, wherein: the first connecting electrode is arranged at the first fracture.
17. A resonator as claimed in claim 12 or 16, characterized in that: the first discontinuity has a width greater than 0.5 microns.
18. A resonator as in any of claims 12-16, characterized in that: the piezoelectric device further comprises an upper electrode and a second connecting electrode, wherein the upper electrode is formed on the piezoelectric layer, and the upper electrode is electrically connected with the second extraction electrode through the second connecting electrode.
19. The resonator of claim 18, wherein: the second extraction electrode has a second fracture between the projection pattern of the first surface and the projection pattern of the upper electrode on the first surface.
20. The resonator of claim 19, wherein: the second connecting electrode is arranged at the second fracture.
21. The resonator of claim 19, wherein: the projection pattern of the second extraction electrode on the first surface and the projection pattern of the upper electrode on the first surface are not provided with second fractures.
22. A resonator as in any of claims 12-21, characterized in that: a seed layer is also provided between the lower electrode, the first extraction electrode, and the second extraction electrode and the carrier.
23. A radio frequency device, characterized by: a resonator network comprising a plurality of resonators, the resonators being as claimed in any one of claims 1 to 22.
24. An electronic device, characterized in that: comprising the radio frequency device of claim 23.
CN202310560475.5A 2023-05-18 2023-05-18 Resonator and preparation method and application thereof Pending CN116614096A (en)

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