CN115694401B - Resonator and preparation method thereof - Google Patents
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- CN115694401B CN115694401B CN202211020879.7A CN202211020879A CN115694401B CN 115694401 B CN115694401 B CN 115694401B CN 202211020879 A CN202211020879 A CN 202211020879A CN 115694401 B CN115694401 B CN 115694401B
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- 239000010410 layer Substances 0.000 claims abstract description 199
- 239000000758 substrate Substances 0.000 claims abstract description 112
- 239000011241 protective layer Substances 0.000 claims abstract description 27
- 238000000034 method Methods 0.000 claims description 35
- 238000004519 manufacturing process Methods 0.000 claims description 19
- 238000000151 deposition Methods 0.000 claims description 11
- 238000005530 etching Methods 0.000 claims description 11
- 239000013078 crystal Substances 0.000 claims description 9
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- 238000010586 diagram Methods 0.000 description 12
- 239000002184 metal Substances 0.000 description 8
- 229910052751 metal Inorganic materials 0.000 description 8
- 230000008021 deposition Effects 0.000 description 5
- 239000000463 material Substances 0.000 description 5
- 239000010409 thin film Substances 0.000 description 5
- 239000010931 gold Substances 0.000 description 4
- 229910052737 gold Inorganic materials 0.000 description 4
- PCHJSUWPFVWCPO-UHFFFAOYSA-N gold Chemical compound [Au] PCHJSUWPFVWCPO-UHFFFAOYSA-N 0.000 description 3
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- 238000000623 plasma-assisted chemical vapour deposition Methods 0.000 description 2
- 238000006243 chemical reaction Methods 0.000 description 1
- 238000005229 chemical vapour deposition Methods 0.000 description 1
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Abstract
The application provides a resonator and a preparation method thereof, and relates to the technical field of resonators, and the resonator comprises a first substrate, and a lower electrode, a piezoelectric layer and a second substrate which are sequentially laminated on the first substrate; forming a first conductive portion and a second conductive portion extending to the piezoelectric layer on the second substrate; forming a protective layer covering the first conductive portion on the second substrate to form an upper cavity between the protective layer and the upper electrode; a lateral release channel is also formed between the second substrate and the piezoelectric layer, which communicates the upper cavity with the second conductive portion. Therefore, when the sacrificial layer is not released in the upper cavity and the second conducting part, the second conducting part laterally releases the lateral release channel and the sacrificial layer in the upper cavity in sequence, so that the hole for the protective layer is prevented from being opened right above the upper cavity, the problem that foreign matters fall into easily when a release hole is formed directly above the upper cavity is avoided, and the stability and the reliability of the device can be further improved.
Description
Technical Field
The application relates to the technical field of resonators, in particular to a resonator and a preparation method thereof.
Background
And the band-pass filter can be manufactured by using resonators with high Q value and high electromechanical coupling coefficient to connect in series and parallel. Thin film bulk acoustic resonators (Film Bulk Acoustic Wave Resonator, FBAR) and bandpass filters are widely used in current communication systems. In order to ensure the communication quality, the performance of the FBAR and the filter needs to be ensured, and the micro device needs to have a quality of high reliability, that is, to maintain stable signal output even under severe conditions such as dust, high temperature, and humidity.
In the prior art, a sandwich stack structure (upper electrode/piezoelectric layer/lower electrode) is generally adopted to realize electromechanical conversion, and an air gap structure is formed above a resonance region, and a thin film on the air gap structure provides protection for the resonator and realizes thin film encapsulation. However, in order to form the air gap structure, release is performed directly above the resonance region, and in this way, foreign matters such as dust can easily enter the resonator directly from the release hole, so that the performance of the device is affected.
Disclosure of Invention
The present invention has been made in view of the above-mentioned drawbacks of the prior art, and an object of the present invention is to provide a resonator and a method for manufacturing the same, which can solve the problem that foreign matters directly enter the resonator from a release hole above the resonator to affect device performance.
In order to achieve the above purpose, the technical solution adopted in the embodiment of the present application is as follows:
in one aspect of the embodiments of the present application, there is provided a resonator including a prefabricated device including a first substrate, and a lower electrode, a piezoelectric layer, and a second substrate sequentially stacked on the first substrate; a first conducting part and a second conducting part extending to the piezoelectric layer are formed on the second substrate, and the second conducting part is positioned on the periphery side of the first conducting part and is arranged at intervals with the first conducting part; an upper electrode is arranged on the piezoelectric layer exposed in the first conducting part; forming a protective layer covering the first conductive portion on the second substrate to form an upper cavity between the protective layer and the upper electrode; a lateral release channel is also formed between the second substrate and the piezoelectric layer, which communicates the upper cavity with the second conductive portion.
Optionally, the first conducting portion and/or the second conducting portion has an inclined sidewall, and the inclined sidewall forms an angle of 20 ° to 80 ° with a plane parallel to the first substrate.
Optionally, a first bonding layer and a second bonding layer which are bonded are further arranged between the first substrate and the lower electrode, and the piezoelectric layer is a monocrystalline piezoelectric layer.
Optionally, a lower cavity is formed on the first bonding layer, the lower cavity is located at one side of the second bonding layer away from the lower electrode, and a bragg reflector located in the lower cavity is arranged on the surface of one side of the second bonding layer away from the lower electrode.
Optionally, the second conducting part comprises a lower electrode lead-out hole and an upper electrode lead-out hole, a first bonding pad electrically connected with the lower electrode is arranged in the lower electrode lead-out hole, a second bonding pad electrically connected with the upper electrode is arranged in the upper electrode lead-out hole, and the lower electrode lead-out hole and/or the upper electrode lead-out hole are/is communicated with the upper cavity through a lateral release channel.
In another aspect of the embodiments of the present application, a method for manufacturing a resonator is provided, including:
providing a prefabricated device, wherein the prefabricated device comprises a first substrate, a lower electrode, a piezoelectric layer, a first sacrificial layer and a second substrate, wherein the lower electrode, the piezoelectric layer, the first sacrificial layer and the second substrate are sequentially stacked on the first substrate;
forming a first conducting part and a second conducting part extending to the piezoelectric layer on the second substrate through etching, wherein the second conducting part is positioned on the periphery side of the first conducting part and is arranged at intervals with the first conducting part, the first sacrificial layer is exposed in the first conducting part and the second conducting part respectively, and the piezoelectric layer is exposed in the first conducting part;
depositing an upper electrode on the piezoelectric layer exposed in the first conductive portion;
filling a second sacrificial layer in contact with the first sacrificial layer in the first conducting part;
forming a protective layer covering the first conductive portion on the second substrate;
releasing the first sacrificial layer through the second conductive portion to form a lateral release channel between the piezoelectric layer and the second substrate;
the second sacrificial layer is laterally released through the lateral release channel to form an upper cavity between the protective layer and the upper electrode.
Optionally, providing the prefabricated device includes:
providing a second substrate;
respectively depositing a first sacrificial layer and a piezoelectric layer on a second substrate, wherein the piezoelectric layer is a monocrystalline piezoelectric layer;
forming a lower electrode on the piezoelectric layer;
and arranging the lower electrode on the first substrate through a bonding process to obtain the prefabricated device.
Optionally, disposing the lower electrode on the first substrate by a bonding process includes:
sequentially forming a second bonding layer and a Bragg reflector on the lower electrode;
forming a first bonding layer having a lower cavity on a first substrate;
the first bonding layer and the second bonding layer are correspondingly bonded so that the Bragg reflector is positioned in the lower cavity.
Optionally, forming the first conductive portion and the second conductive portion on the second substrate by etching includes:
and forming a first conducting part and a second conducting part with inclined side walls on the second substrate through wet isotropic etching, wherein the included angle between the inclined side walls and a plane parallel to the first substrate is 20-80 degrees.
Optionally, the second conducting part comprises a lower electrode lead-out hole and an upper electrode lead-out hole, and the lower electrode lead-out hole and/or the upper electrode lead-out hole are communicated with the upper cavity through a lateral release channel; after forming the first conductive portion and the second conductive portion on the second substrate by etching, the method further includes:
a first bonding pad electrically connected with the lower electrode is arranged in the lower electrode lead-out hole, and a second bonding pad electrically connected with the upper electrode is arranged in the upper electrode lead-out hole.
The beneficial effects of this application include:
the application provides a resonator and a preparation method thereof, wherein the resonator comprises a prefabricated device, and the prefabricated device comprises a first substrate, a lower electrode, a piezoelectric layer and a second substrate which are sequentially laminated on the first substrate; a first conducting part and a second conducting part extending to the piezoelectric layer are formed on the second substrate, and the second conducting part is positioned on the periphery side of the first conducting part and is arranged at intervals with the first conducting part; an upper electrode is arranged on the piezoelectric layer exposed in the first conducting part; forming a protective layer covering the first conductive portion on the second substrate to form an upper cavity between the protective layer and the upper electrode; a lateral release channel is also formed between the second substrate and the piezoelectric layer, which communicates the upper cavity with the second conductive portion. Therefore, when the sacrificial layer is not released in the upper cavity and the second conducting part, the second conducting part laterally releases the lateral release channel and the sacrificial layer in the upper cavity in sequence, so that the hole for the protective layer is prevented from being opened right above the upper cavity, the problem that foreign matters fall into easily when a release hole is formed directly above the upper cavity is avoided, and the stability and the reliability of the device can be further improved.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings that are needed in the embodiments will be briefly described below, it being understood that the following drawings only illustrate some embodiments of the present application and therefore should not be considered limiting the scope, and that other related drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.
Fig. 1 is a schematic flow chart of a method for manufacturing a resonator according to an embodiment of the present application;
fig. 2 is a schematic state diagram of a method for manufacturing a resonator according to an embodiment of the present application;
FIG. 3 is a second schematic diagram of a method for manufacturing a resonator according to an embodiment of the present disclosure;
FIG. 4 is a third schematic diagram illustrating a method for manufacturing a resonator according to an embodiment of the present disclosure;
FIG. 5 is a schematic diagram showing a state of a method for manufacturing a resonator according to an embodiment of the present disclosure;
FIG. 6 is a schematic diagram showing a state of a method for manufacturing a resonator according to an embodiment of the present disclosure;
FIG. 7 is a schematic diagram showing a state of a method for manufacturing a resonator according to an embodiment of the present disclosure;
FIG. 8 is a schematic diagram of a resonator manufacturing method according to an embodiment of the present disclosure;
FIG. 9 is a schematic diagram illustrating a state of a method for manufacturing a resonator according to an embodiment of the present disclosure;
FIG. 10 is a diagram illustrating a state of a method for manufacturing a resonator according to an embodiment of the present disclosure;
FIG. 11 is a schematic diagram showing a state of a method for manufacturing a resonator according to an embodiment of the present disclosure;
FIG. 12 is a schematic diagram of an eleventh state of a method for manufacturing a resonator according to an embodiment of the present disclosure;
fig. 13 is a schematic structural diagram of a resonator according to an embodiment of the present application.
Icon: a 10-Bragg reflector; 11-a second substrate; 12-a first sacrificial layer; 13-a piezoelectric layer; 14-extracting electrodes; 15-a second bonding layer; 16-a layer of high acoustic impedance material; 17-a layer of low acoustic impedance material; 21-a first substrate; 22-a first bonding layer; 31-a bonding layer; 32-upper electrode; 33-a protective layer; 34-gold ball terminal; 35-a lower electrode; 36-a first lead-out hole; 37-a second exit hole; 38-a third lead-out hole; 39-grooves; 40-lower cavity; 41-a first conduction part; 42-a second conduction part; 43-a second sacrificial layer; 44-upper cavity; 45-lateral release channel; 46-a base layer; 47-second bonding pads; 48-first pads.
Detailed Description
The embodiments set forth below represent the information necessary to enable those skilled in the art to practice the embodiments and illustrate the best mode of practicing the embodiments. Upon reading the following description in light of the accompanying drawing figures, those skilled in the art will understand the concepts of the disclosure and will recognize applications of these concepts not particularly addressed herein. It should be understood that these concepts and applications fall within the scope of the disclosure and the accompanying claims.
It will be understood that, although the terms first, second, etc. may be used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another element. For example, a first element could be termed a second element, and, similarly, a second element could be termed a first element, without departing from the scope of the present disclosure. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items.
It will be understood that when an element such as a layer, region or substrate is referred to as being "on" or extending "onto" another element, it can be directly on or extend directly onto the other element or intervening elements may also be present. In contrast, when an element is referred to as being "directly on" or "directly extending onto" another element, there are no intervening elements present. Also, it will be understood that when an element such as a layer, region or substrate is referred to as being "on" or extending "over" another element, it can be directly on or extend directly over the other element or intervening elements may also be present. In contrast, when an element is referred to as being "directly on" or extending "directly over" another element, there are no intervening elements present. It will also be understood that when an element is referred to as being "connected" or "coupled" to another element, it can be directly connected or coupled to the other element or intervening elements may be present. In contrast, when an element is referred to as being "directly connected" or "directly coupled" to another element, there are no intervening elements present.
Related terms such as "below" or "above" … "or" upper "or" lower "or" horizontal "or" vertical "may be used herein to describe one element, layer or region's relationship to another element, layer or region as illustrated in the figures. It should be understood that these terms, and those terms discussed above, are intended to encompass different orientations of the device in addition to the orientation depicted in the figures.
The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the disclosure. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises" and/or "comprising," when used herein, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof.
Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs. It will be further understood that terms used herein should be interpreted as having a meaning that is consistent with their meaning in the context of this specification and the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.
In an aspect of the embodiment of the present application, there is provided a resonator, as shown in fig. 13, including a prefabricated device including a first substrate 21 and a lower electrode 35, a piezoelectric layer 13, and a second substrate 11 sequentially stacked on the first substrate 21; the first conductive portion 41 and the second conductive portion 42 extending to the piezoelectric layer 13 are formed on the second substrate 11, wherein the first conductive portion 41 and the second conductive portion 42 may be through holes penetrating the second substrate 11 or through grooves extending from a side surface of the second substrate 11 facing away from the piezoelectric layer 13 to the piezoelectric layer 13.
With continued reference to fig. 13, the second conductive portion 42 is located at a peripheral side of the first conductive portion 41, and the second conductive portion 42 is spaced apart from the first conductive portion 41, so that the first conductive portion 41 and the second conductive portion 42 are spaced apart on the second substrate 11.
An upper electrode 32 is provided on the piezoelectric layer 13 exposed in the first conductive portion 41; forming a protective layer 33 covering the first conductive portions 41 on the second substrate 11 such that an upper cavity 44 is formed between the protective layer 33 and the upper electrode 32 after the lateral release; a lateral release passage 45 communicating the upper cavity 44 and the second conduction portion 42 is also formed between the second substrate 11 and the piezoelectric layer 13. According to the method and the device, when the sacrificial layer is not released in the upper cavity and the second conducting part, the second conducting part laterally releases the lateral release channel and the sacrificial layer in the upper cavity in sequence, so that the hole for the protective layer is prevented from being opened right above the upper cavity, the problem that foreign matters fall into easily when a release hole is formed directly above the upper cavity is avoided, and the stability and the reliability of the device can be further improved.
Optionally, the first conducting portion 41 and/or the second conducting portion 42 have inclined sidewalls, and an included angle between the inclined sidewalls and a plane parallel to the first substrate 21 is 20 ° to 80 °, so that reflection in all directions can be provided for the transverse sound wave by using the structure with the inclined sidewalls, thereby avoiding forming a standing wave pseudo mode and further improving device performance.
Optionally, a first bonding layer 22 and a second bonding layer 15 are further bonded between the first substrate 21 and the lower electrode 35, and the piezoelectric layer 13 is a single crystal piezoelectric layer, as shown in fig. 1 to 12, so that the single crystal piezoelectric layer can be manufactured by a substrate transfer and bonding mode, which is helpful for improving the performance of the device.
Alternatively, as shown in fig. 13, a lower cavity 40 (groove 39) is formed on the first bonding layer, the lower cavity 40 is located on the side of the second bonding layer 15 facing away from the lower electrode 35, and a bragg mirror 10 is provided in the lower cavity 40 on the surface of the side of the second bonding layer 15 facing away from the lower electrode 35. Thus, the first reflection for resonator acoustic wave reflection can be provided by the Bragg reflector 10 on the side of the lower electrode 35 near the first substrate 21, thereby improving device performance. The lower cavity 40 provides a second reflection for resonator acoustic wave reflection on the side of the lower electrode 35 adjacent to the first substrate 21, and the lower cavity 40 cooperates with the Bragg reflector 10 to further improve device performance.
Optionally, as shown in fig. 13, the second conducting portion 42 includes a lower electrode lead-out hole and an upper electrode lead-out hole, which are respectively located at the left and right sides of the first conducting portion 41, a first bonding pad 48 electrically connected to the lower electrode is disposed in the lower electrode lead-out hole, a second bonding pad 47 electrically connected to the upper electrode is disposed in the upper electrode lead-out hole, and the lower electrode lead-out hole and/or the upper electrode lead-out hole are communicated with the upper cavity through a lateral release channel, so that the sacrificial layer in the upper cavity can be released through the lateral release channel in a lateral release manner, thereby forming the upper cavity.
In another aspect of the embodiments of the present application, a method for preparing a resonator is provided, as shown in fig. 1, where the method includes:
s010: a prefabricated device is provided, the prefabricated device comprises a first substrate, and a lower electrode, a piezoelectric layer, a first sacrificial layer and a second substrate which are sequentially stacked on the first substrate.
As shown in fig. 6, a prefabricated device is provided first, and the prefabricated device may include a first substrate 21, a lower electrode 35, a piezoelectric layer 13, a first sacrificial layer 12 and a second substrate 11, where the lower electrode 35, the piezoelectric layer 13, the first sacrificial layer 12 and the second substrate 11 are sequentially stacked on the first substrate 21, and only a positional relationship between the four is referred to, and no process sequence of table preparation is taken, for example, the lower electrode 35 and the piezoelectric layer 13 are taken as an example, and in different processes: the piezoelectric layer 13 may be prepared after the lower electrode 35 is prepared; the piezoelectric layer 13 may be prepared first, and then the lower electrode 35 may be prepared.
The first sacrificial layer 12 is located on a side surface of the second substrate 11 near the first substrate 21, and the first sacrificial layer 12 is a patterned structure for forming a subsequent lateral release channel 45.
S020: and forming a first conducting part and a second conducting part which extend to the piezoelectric layer on the second substrate through etching, wherein the second conducting part is positioned on the periphery side of the first conducting part and is arranged at intervals with the first conducting part, the first sacrificial layer is respectively exposed in the first conducting part and the second conducting part, and the piezoelectric layer is exposed in the first conducting part.
As shown in fig. 7, the second substrate 11 is etched so that first conductive portions 41 and second conductive portions 42 penetrating the second substrate 11 are formed in the surface of the second substrate 11 facing away from the first substrate 21, respectively, the second conductive portions 42 being located on the peripheral side of the first conductive portions 41 and spaced apart from the first conductive portions 41 so as not to communicate with each other, in other words, the first conductive portions 41 and the second conductive portions 42 are spaced apart in the horizontal direction. The piezoelectric layer 13 and a part of the first sacrificial layer 12 are exposed in the first conductive portion 41, and the other part of the first sacrificial layer 12 is exposed in the second conductive portion 42, whereby the first conductive portion 41 and the second conductive portion 42 can be communicated through the first sacrificial layer 12.
S030: an upper electrode is deposited on the piezoelectric layer exposed in the first via.
As shown in fig. 8, the upper electrode 32 may be deposited on the surface of the piezoelectric layer 13 exposed in the first conductive portion 41, and it should be understood that the upper electrode 32, the piezoelectric layer 13, and the lower electrode 35 can form a piezoelectric stack structure having an overlapping region, i.e., a sandwich structure, where the overlapping region serves as an effective operation region of the resonator. In order to facilitate subsequent lateral release, after the upper electrode 32 is formed, the first sacrificial layer 12 exposed in the first conductive portion 41 is still partially exposed.
S040: and filling a second sacrificial layer in contact with the first sacrificial layer in the first conducting part.
As shown in fig. 10, the second sacrificial layer 43 is filled in the first via portion 41 such that the second sacrificial layer 43 covers the upper electrode 32, and the second sacrificial layer 43 also extends to the surface of the first sacrificial layer 12 and contacts the first sacrificial layer 12, i.e., the first sacrificial layer 12 and the second sacrificial layer 43 form a zigzag structure.
S050: a protective layer is formed on the second substrate to cover the first conductive portion.
As shown in fig. 11, a protective layer 33 is formed on the second substrate 11 to cover the first conductive portions 41, i.e., the protective layer 33 is covered on the second sacrificial layer 43. The thickness of the protective layer 33 is 500nm.
S060: the first sacrificial layer is released through the second via to form a lateral release channel between the piezoelectric layer and the second substrate.
As shown in fig. 13, since another portion of the first sacrificial layer 12 remains exposed in the second conductive portion 42, the first sacrificial layer 12 can be released through the first sacrificial layer 12 exposed in the second conductive portion 42 to form the lateral release passage 45.
S070: the second sacrificial layer is laterally released through the lateral release channel to form an upper cavity between the protective layer and the upper electrode.
As shown in fig. 13, as the first sacrificial layer 12 is completely released, the lateral release channel 45 also extends from the second conducting portion 42 into the first conducting portion 41, so that the lateral release channel 45 is connected to the second sacrificial layer 43, and the second sacrificial layer 43 is released together, so that the space in the first conducting portion 41 is released, an upper cavity 44 is formed between the lower electrode 35 and the protective layer 33, and the protective layer 33 can serve as a thin film to provide good protection for the resonator and can serve as a reflective boundary above the resonator, so as to improve the performance of the device.
Therefore, the first sacrificial layer 12 and the second sacrificial layer 43 which are in contact with each other can be utilized to realize that the second sacrificial layer 43 in the first conducting part 41 is released from the side direction of the second conducting part 42, the protective layer 33 is not perforated right above the first conducting part 41, the problem that foreign matters are easy to fall into when a release hole is directly formed above the first conducting part 41 is avoided, and therefore the stability and the reliability of the device can be further improved.
It should be understood that one or more first sacrificial layers 12 may be provided, and when there are a plurality of first sacrificial layers 12, a plurality of lateral release channels 45 may be correspondingly formed, for example, two first sacrificial layers 12 are shown in fig. 11, and two lateral release channels 45 are correspondingly formed after release, as shown in fig. 13.
Referring to fig. 2 to 6, when a prefabricated device is provided through S010, it may be performed by:
s011: a second substrate 11 is provided.
As shown in fig. 2, a second substrate 11 may be provided first.
S012: a first sacrificial layer 12 and a piezoelectric layer 13 are deposited on the second substrate 11, respectively, the piezoelectric layer 13 being a monocrystalline piezoelectric layer 13.
As shown in fig. 2, next, the first sacrificial layer 12 and the piezoelectric layer 13 are respectively deposited on the second substrate 11, and the piezoelectric layer 13 may be deposited in an integral layer, that is, while the piezoelectric layer 13 covers the first sacrificial layer 12, the effective working area is attached to the second substrate 11, so that the upper electrode 32 is exposed and formed conveniently when the first conductive portion 41 is etched and formed.
S013: a lower electrode 35 is formed on the piezoelectric layer 13.
S014: the lower electrode 35 is provided to the first substrate 21 by a bonding process to obtain a prefabricated device.
As shown in fig. 5 and 6, the lower electrode 35 is provided to the first substrate 21 by a bonding process to obtain a prefabricated device.
In this process, since the piezoelectric layer 13 is formed before the lower electrode 35, the single crystal piezoelectric layer 13 can be formed directly under a high temperature environment, and then the lower electrode 35 is deposited, so that the piezoelectric layer 13 can be prevented from being in a polycrystalline state due to the limitation of the metal electrode on temperature (the metal electrode is easy to cause defects due to oxidation failure under the high temperature environment), which is beneficial to improving the quality of the piezoelectric layer 13, and further improving the performance of the resonator.
For example, S012 deposits a single crystal piezoelectric layer 13 on the second substrate 11 and the first sacrificial layer 12 at a high temperature using a Metal-organic vapor deposition method (Metal-organic Chemical Vapor Deposition, MOCVD) at a deposition temperature of between 1000 ℃ and 1300 ℃ and a deposition thickness in a range of between 10nm and 900 nm. S013 is that when the lower electrode 35 is deposited on the piezoelectric layer 13 at a low temperature, the deposition temperature is between 150 ℃ and 250 ℃, and the deposition thickness range is between 10nm and 3000 nm. The upper electrode 32 may refer to the manufacturing process of the lower electrode 35.
S014, when the lower electrode 35 is provided to the first substrate 21 by the bonding process: as shown in fig. 3, the second bonding layer 15 is first deposited on the surfaces of the piezoelectric layer 13 and the lower electrode 35 by a plasma enhanced chemical vapor deposition method, and the deposition thickness ranges from 200nm to 5000 nm. As shown in fig. 4, the bragg reflector 10 located in the effective operating region is then formed on the second bonding layer 15, and the bragg reflector 10 may be formed by alternately stacking the high acoustic impedance material layer 16 and the low acoustic impedance material layer 17. As shown in fig. 5, a first bonding layer 22 having a lower cavity 40 (recess 39) is formed on a first substrate 21, and the first bonding layer 22 may be deposited by a plasma enhanced chemical vapor deposition method to a thickness ranging from 200nm to 5000 nm. The grooves 39 are used for Rong Zhibu the bragg reflector 10, and then the first bonding layer 22 and the second bonding layer 15 are correspondingly bonded to form the bonding layer 31 as shown in fig. 6, so that the bragg reflector 10 is accommodated by the grooves 39 to obtain a prefabricated device. Thus, the first reflection for resonator acoustic wave reflection can be provided by the Bragg reflector 10 on the side of the lower electrode 35 near the first substrate 21, thereby improving device performance.
Since the Bragg reflector 10 is formed after the single crystal piezoelectric layer 13, there is no problem that the growth quality of the single crystal piezoelectric layer 13 is poor due to mismatch of the Bragg reflector 10 material and the crystal quality of the single crystal piezoelectric thin film as in the conventional process.
In some embodiments, as shown in fig. 6, the internal space of the groove 39 is larger than the space occupied by the bragg reflector 10, in other words, a certain space is provided between the internal wall surface of the groove 39 and the bragg reflector 10, and the lower cavity 40 can provide a second reflection for the acoustic wave reflection of the resonator on the side of the lower electrode 35 close to the first substrate 21, so that the performance of the device is further improved by cooperation of the lower cavity 40 and the bragg reflector 10.
S013 forming the lower electrode 35 on the piezoelectric layer 13 includes: as shown in fig. 2, by first etching the piezoelectric layer 13, a first extraction hole 36, a second extraction hole 37, and a third extraction hole 38 that are spaced apart from each other and penetrate to the second substrate 11 are formed on the piezoelectric layer 13, then a metal layer is deposited on the piezoelectric layer 13, and the metal layer is patterned so as to form two portions that are spaced apart, one portion serving as a lower electrode 35 and the other portion serving as an extraction electrode 14 (serving as a lateral extraction of the upper electrode 32), wherein the lower electrode 35 covers an effective operation area and extends into the first extraction hole 36, and the extraction electrode 14 is located in the second extraction hole 37 and extends into the third extraction hole 38.
As shown in fig. 7, when the first conductive portion 41 and the second conductive portion 42 are formed on the second substrate 11 by S020, two second conductive portions 42 (lower electrode lead-out hole and upper electrode lead-out hole) can be formed, whereby the first lead-out hole 36 formed by S013 is exposed in the second conductive portion 42 (upper electrode lead-out hole) on the left side in fig. 7, the third lead-out hole 38 is exposed in the second conductive portion 42 (lower electrode lead-out hole) on the right side in fig. 7, and the second lead-out hole 37 is exposed in the first conductive portion 41 in the middle. Thus, as shown in fig. 8, after the upper electrode 32 is deposited in the first conducting portion 41, the upper electrode 32 is in contact with the extraction electrode 14 in the second extraction hole 37, so that the upper electrode 32 can be extracted laterally from the extraction electrode 14 into the second conducting portion 42 on the right side, thereby facilitating subsequent packaging.
As shown in fig. 13, after depositing the upper electrode 32 on the piezoelectric layer 13 exposed in the first conductive portion 41 through S030, the method further includes: depositing a first pad 48 in the second conduction portion 42 on the right in fig. 12, the first pad 48 being in contact with the lower electrode 35 in the first extraction hole 36, thereby extracting the lower electrode 35; a second land 47 is deposited in the second conduction portion 42 on the left in fig. 12, and the second land 47 is in contact with the extraction electrode 14 in the third extraction hole 38, whereby the upper electrode 32 is extracted laterally by the extraction electrodes 14 in the second extraction hole 37 to the extraction electrodes 14 in the third extraction hole 38.
As shown in fig. 12 and 13, each of the first and second pads 48 and 47 may include a base layer 46 and gold ball terminals 34 on the base layer 46. Specific:
with continued reference to fig. 8, when the first lead-out hole 36 and the third lead-out hole 38 are provided, the lower electrode 35 and the upper electrode 32 may be led out into the corresponding second conductive portion 42 through both, so that, for convenience of packaging, the foundation layer 46 may be formed in the second conductive portion 42 exposed by the first lead-out hole 36 and the third lead-out hole 38 simultaneously when the upper electrode 32 is deposited in the first conductive portion 41, one of the foundation layers 46 is in contact with the lower electrode 35 in the first lead-out hole 36, the other foundation layer 46 is in contact with the lead-out electrode 14 in the third lead-out hole 38, for example, when S030 is performed, metal is deposited in the first conductive portion 41 and the two second conductive portions 42, respectively, the metal in the first conductive portion 41 is the upper electrode 32, and the metal in the two second conductive portions 42 is the foundation layer 46.
As shown in fig. 12, metal is deposited on the base layer 46 to form the gold ball terminals 34 covering the base layer 46, and by forming the base layer 46 first, the arrangement area of the gold ball terminals 34 can be increased, thereby improving the reliability of the device.
Referring to fig. 7, when forming the first conductive portion 41 and the second conductive portion 42 on the second substrate 11 by S020: the first conducting portion 41 and the second conducting portion 42 can be formed on the second substrate 11 through wet isotropic etching, so that the side walls of the first conducting portion 41 and the second conducting portion 42 are inclined side walls, and therefore reflection in all directions can be provided for transverse sound waves by utilizing a structure with inclined side walls, standing wave pseudo modes are avoided, and device performance is further improved.
In some embodiments, as shown in fig. 8 to 9, before forming the protective layer 33 covering the first conductive portion 41 on the second substrate 11, the method further includes: the second substrate 11 is thinned, thereby facilitating miniaturization of the device.
The foregoing description is only of the preferred embodiments of the present application and is not intended to limit the same, but rather, various modifications and variations may be made by those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application should be included in the protection scope of the present application.
Claims (8)
1. A resonator, comprising a prefabricated device, wherein the prefabricated device comprises a first substrate, and a lower electrode, a piezoelectric layer and a second substrate which are sequentially stacked on the first substrate;
a first conductive portion and a second conductive portion extending to the piezoelectric layer are formed on the second substrate, the second conductive portion being located on a peripheral side of the first conductive portion and being spaced apart from the first conductive portion;
an upper electrode is arranged on the piezoelectric layer exposed in the first conducting part;
forming a protective layer covering the first conductive portion on the second substrate to form an upper cavity between the protective layer and the upper electrode;
a lateral release channel which is communicated with the upper cavity and the second conducting part is also formed between the second substrate and the piezoelectric layer;
the second conducting part comprises a lower electrode leading-out hole and an upper electrode leading-out hole, a first bonding pad electrically connected with the lower electrode is arranged in the lower electrode leading-out hole, a second bonding pad electrically connected with the upper electrode is arranged in the upper electrode leading-out hole, and the lower electrode leading-out hole and/or the upper electrode leading-out hole are/is communicated with the upper cavity through the lateral release channel.
2. A resonator as claimed in claim 1, wherein the first and/or second conducting section has an inclined side wall at an angle of 20 ° to 80 ° to a plane parallel to the first substrate.
3. The resonator of claim 1, wherein a first bonding layer and a second bonding layer are further provided between the first substrate and the lower electrode, and the piezoelectric layer is a single crystal piezoelectric layer.
4. A resonator as claimed in claim 3, characterized in that a lower cavity is formed in the first bonding layer, which lower cavity is located on the side of the second bonding layer facing away from the lower electrode, and a bragg mirror is provided in the lower cavity on the surface of the side of the second bonding layer facing away from the lower electrode.
5. A method of manufacturing a resonator, the method comprising:
providing a prefabricated device, wherein the prefabricated device comprises a first substrate, and a lower electrode, a piezoelectric layer, a first sacrificial layer and a second substrate which are sequentially laminated on the first substrate;
forming a first conducting part and a second conducting part extending to the piezoelectric layer on the second substrate through etching, wherein the second conducting part is positioned on the periphery side of the first conducting part and is arranged at intervals with the first conducting part, the first sacrificial layer is exposed in the first conducting part and the second conducting part respectively, and the piezoelectric layer is exposed in the first conducting part;
depositing an upper electrode on the piezoelectric layer exposed in the first conductive portion;
filling a second sacrificial layer in contact with the first sacrificial layer in the first conducting part;
forming a protective layer covering the first conductive portion on the second substrate;
releasing the first sacrificial layer through the second conductive portion to form a lateral release channel between the piezoelectric layer and the second substrate;
laterally releasing the second sacrificial layer through the lateral release channel to form an upper cavity between the protective layer and the upper electrode;
the second conducting part comprises a lower electrode lead-out hole and an upper electrode lead-out hole, and the lower electrode lead-out hole and/or the upper electrode lead-out hole are/is communicated with the upper cavity through the lateral release channel; after the first conductive portion and the second conductive portion are formed on the second substrate by etching, the method further includes:
a first bonding pad electrically connected with the lower electrode is arranged in the lower electrode lead-out hole, and a second bonding pad electrically connected with the upper electrode is arranged in the upper electrode lead-out hole.
6. The method of manufacturing a resonator according to claim 5, wherein providing a prefabricated device comprises:
providing a second substrate;
respectively depositing the first sacrificial layer and the piezoelectric layer on the second substrate, wherein the piezoelectric layer is a monocrystalline piezoelectric layer;
forming the lower electrode on the piezoelectric layer;
and arranging the lower electrode on the first substrate through a bonding process to obtain the prefabricated device.
7. The method of manufacturing a resonator according to claim 6, wherein the disposing the lower electrode to the first substrate by a bonding process comprises:
sequentially forming a second bonding layer and a Bragg reflector on the lower electrode;
forming a first bonding layer having a lower cavity on the first substrate;
and correspondingly bonding the first bonding layer and the second bonding layer so that the Bragg reflector is positioned in the lower cavity.
8. The method of manufacturing a resonator according to claim 5, wherein forming the first conductive section and the second conductive section on the second substrate by etching comprises:
and forming the first conductive part and the second conductive part with inclined side walls on the second substrate through wet isotropic etching, wherein the inclined side walls form an included angle of 20-80 degrees with a plane parallel to the first substrate.
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| KR102369434B1 (en) * | 2017-04-19 | 2022-03-03 | 삼성전기주식회사 | Bulk-acoustic wave resonator and method for manufacturing the same |
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