WO2020124369A1 - 薄膜体声波谐振器及其制作方法、滤波器 - Google Patents

薄膜体声波谐振器及其制作方法、滤波器 Download PDF

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Publication number
WO2020124369A1
WO2020124369A1 PCT/CN2018/121770 CN2018121770W WO2020124369A1 WO 2020124369 A1 WO2020124369 A1 WO 2020124369A1 CN 2018121770 W CN2018121770 W CN 2018121770W WO 2020124369 A1 WO2020124369 A1 WO 2020124369A1
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lower electrode
layer
piezoelectric
substrate
film
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PCT/CN2018/121770
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English (en)
French (fr)
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彭波华
胡念楚
贾斌
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开元通信技术（厦门）有限公司
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Priority to PCT/CN2018/121770 priority Critical patent/WO2020124369A1/zh
Publication of WO2020124369A1 publication Critical patent/WO2020124369A1/zh

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    • 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
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
    • H03H9/00—Networks comprising electromechanical or electro-acoustic devices; Electromechanical resonators
    • H03H9/15—Constructional features of resonators consisting of piezoelectric or electrostrictive material
    • H03H9/17—Constructional features of resonators consisting of piezoelectric or electrostrictive material having a single resonator
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
    • H03H9/00—Networks comprising electromechanical or electro-acoustic devices; Electromechanical resonators
    • H03H9/46—Filters
    • H03H9/54—Filters comprising resonators of piezoelectric or electrostrictive material

Definitions

  • the present disclosure belongs to the technical field of wireless communication, and more particularly relates to a thin film bulk acoustic resonator, a manufacturing method thereof, and a filter.
  • Thin film bulk acoustic resonator relies on the advantages of high Q value, large coupling coefficient, etc., and is used in today's RF filters and oscillators.
  • an oscillator made by FBAR usually mounts FBAR on a printed circuit board (PCB) containing metal and laminated media.
  • PCB printed circuit board
  • the PCB board will deform, and the generated stress will be transferred to the FBAR, resulting in a change in the resonance frequency.
  • the frequency of change is small, it is more serious than the frequency deviation caused by aging and other factors, and it is difficult to quantify.
  • GPS devices require frequency deviation to be controlled within ⁇ 0.5ppm
  • wireless applications such as Wifi and Bluetooth only allow frequency deviation to be within ⁇ 10ppm. Therefore, it is very important to reduce the influence of external stress on the frequency of the acoustic resonator.
  • the existing thin film bulk acoustic waves and filters and oscillators generally have many layers of materials, the process is relatively complicated, the external stress is easily transmitted to the resonant device, and the frequency deviation is serious, which cannot effectively reduce the external stress on the frequency of the acoustic resonator. Impact.
  • the present disclosure provides a thin film bulk acoustic wave resonator, a manufacturing method thereof, and a filter to at least partially solve the above technical problems.
  • a thin film bulk acoustic resonator including:
  • a center pillar structure is formed at an eccentric position of the thin film bulk acoustic resonator, and a cavity is formed around the center pillar structure.
  • the piezoelectric stack structure includes a lower electrode layer, an upper electrode layer, and a piezoelectric layer between the lower electrode layer and the upper electrode layer; the lower electrode and the substrate surround ⁇ hollow cavity.
  • the piezoelectric stack structure includes a lower electrode layer, an upper electrode layer, and a piezoelectric layer between the lower electrode layer and the upper electrode layer; the thin film bulk acoustic wave resonator further includes The conductive layer between the substrate and the lower electrode layer forms the cavity between the lower electrode and the conductive layer.
  • the lower electrode layer includes a first lower electrode and a second lower electrode
  • the first lower electrode includes a first part, a second part, a third part, and a fourth part connected in sequence, wherein the first part and the fourth part are in contact with the substrate, and the first part and the third part are parallel to The direction of the substrate extends, and the second portion and the fourth portion extend in a direction perpendicular to the substrate;
  • the second lower electrode includes a first part, a second part, a third part, a fourth part, and a fifth part connected in sequence, wherein the first part and the fifth part of the second lower electrode are in contact with the substrate , And the first, third, and fifth portions of the second lower electrode extend in a direction parallel to the substrate, and the second and fourth portions of the second lower electrode are perpendicular to the substrate The direction of the bottom extends.
  • the piezoelectric layer includes a first piezoelectric film and a second piezoelectric film, the first piezoelectric film completely covers the fourth portion of the first lower electrode and completely covers or partially covers the first lower electrode The third part of the electrode;
  • the second piezoelectric film partially covers the first part of the second lower electrode, completely covers the second part of the second lower electrode, and completely or partially covers the third part of the second lower electrode.
  • the upper electrode layer includes:
  • the first part extends in a direction perpendicular to the substrate, its bottom is in contact with the substrate and the first part of the second lower electrode at the same time, and the first part of the upper electrode layer is located on the first piezoelectric film and Between the second piezoelectric films;
  • the second part located on the piezoelectric layer, extends in a direction parallel to the substrate.
  • the thin film bulk acoustic resonator further includes a spacer layer, the spacer layer includes a first spacer film and a second spacer film;
  • the first spacer film is located between the first piezoelectric film and the upper electrode layer, and the bottom is in contact with the substrate; the second spacer film is located on the second piezoelectric film and the upper Between the electrode layers, and the bottom is in contact with the first portion of the second lower electrode; or
  • the first spacer film is located between the first lower electrode and the first piezoelectric film, and the bottom is in contact with the substrate; the second spacer film is located between the second lower electrode and the first Between the two piezoelectric films, and the bottom is in contact with the first portion of the second lower electrode.
  • the thin film bulk acoustic resonator further includes a first protrusion and a second protrusion
  • the first protrusion is located between the upper electrode layer and the first piezoelectric film and at one end of the second portion of the upper electrode layer; or the first protrusion is located at the first piezoelectric film Between the third portion of the first lower electrode and at one end of the first piezoelectric film;
  • the second protrusion is located between the upper electrode layer and the second piezoelectric film, and is located at the other end of the second portion of the upper electrode layer; or the second protrusion is located at the second Between the piezoelectric film and the third portion of the second lower electrode, and at one end of the second piezoelectric film.
  • the thin film bulk acoustic resonator further includes a pad layer, which is located on the upper electrode layer and the lower electrode layer.
  • the pad layer partially covers the second portion of the upper electrode layer, the first portion of the first lower electrode, and the fifth portion or first portion of the second lower electrode.
  • the conductive layer includes a first conductive film and a second conductive film
  • the lower electrode layer includes a first lower electrode and a second lower electrode; the first lower electrode includes a connected first portion and a second portion; the first portion of the first lower electrode extends in a direction parallel to the substrate, The second portion of the lower electrode extends in a direction perpendicular to the substrate and contacts the substrate, and there is a gap between the first portion of the first lower electrode and the first conductive film; the second lower The electrode extends in a direction parallel to the substrate, and has a gap with the second conductive film.
  • the piezoelectric layer includes a first piezoelectric film and a second piezoelectric film, the first piezoelectric film completely covers the first portion and the second portion of the first lower electrode; the second pressure The electric film completely covers the second lower electrode.
  • the upper electrode layer includes: a first portion extending in a direction perpendicular to the substrate, the bottom of which is in contact with the substrate and the second conductive film at the same time, and the first part of the upper electrode layer One part is located between the first piezoelectric film and the second piezoelectric film; and the second part is located on the piezoelectric layer and extends in a direction parallel to the substrate.
  • the thin film bulk acoustic resonator further includes a spacer layer, the spacer layer includes a first spacer film and a second spacer film; the first spacer film is located on the first piezoelectric film and the upper Between the electrode layers, and the bottom is in contact with the substrate; the second spacer film is located between the second piezoelectric film and the upper electrode layer, and the bottom is in contact with the second conductive film.
  • the piezoelectric layer includes a first piezoelectric film and a second piezoelectric film, the first piezoelectric film is formed on the third portion of the first lower electrode, and the second piezoelectric film is formed on On the third part of the second lower electrode.
  • the upper electrode layer includes: a first portion extending in a direction perpendicular to the substrate, the bottom of which is in contact with the substrate and the first portion of the second lower electrode at the same time, and the upper electrode
  • the first part of the layer is located between the first piezoelectric film and the second piezoelectric film and between the fourth part of the first lower electrode and the second part of the second lower electrode; and the second part, Located on the piezoelectric layer, extending in a direction parallel to the substrate.
  • the thin film bulk acoustic resonator further includes a spacer layer, the spacer layer includes a first spacer film and a second spacer film; the bottom of the first spacer film is in contact with the substrate, and Completely covering the fourth portion of the first lower electrode, partially covering the third portion of the first lower electrode, and partially covering the first piezoelectric film; the bottom of the first spacer film and the second lower electrode The first portion of the electrode is in contact and completely covers the second portion of the second lower electrode, partially covers the third portion of the second lower electrode, and partially covers the second piezoelectric film.
  • the center pillar structure includes: a portion of the upper electrode layer perpendicular to the substrate, a portion of the spacer layer perpendicular to the substrate, and a portion of the piezoelectric layer A portion of the substrate perpendicular to the portion of the lower electrode layer that is perpendicular to the substrate and close to the spacer layer.
  • a method for manufacturing a thin film bulk acoustic resonator including:
  • the sacrificial layer is removed by etching, and a cavity is formed between the lower electrode and the substrate and an effective resonance region of the thin film bulk acoustic resonator.
  • the method for manufacturing the thin film bulk acoustic resonator further includes: between the lower electrode layer and the piezoelectric layer or between the piezoelectric layer and the piezoelectric layer and the upper An isolation layer is grown between the electrode layers and imaged.
  • the method before growing the sacrificial layer, the method further includes: growing a conductive layer and performing image processing.
  • the manufacturing method of the thin film bulk acoustic resonator further includes: forming a convex structure between the lower electrode layer and the piezoelectric layer or between the piezoelectric layer and the upper electrode .
  • a filter including a plurality of said thin film bulk acoustic resonators cascaded.
  • a thin film bulk acoustic resonator, its manufacturing method, and a filter of the present disclosure have at least one of the following beneficial effects:
  • the present disclosure reduces the influence of external stress on the resonance frequency of the device, and is suitable for applications requiring higher frequency stability.
  • the process of the present disclosure is relatively simple, does not require chemical mechanical polishing (CMP) treatment of the sacrificial layer, and can also reduce the number of grown material layers, which reduces the manufacturing cost
  • the pad structure of the present disclosure can reduce the connection resistance, and at the same time the first pad is located in the center pillar area, which can strengthen the center pillar structure.
  • the two ends of the first pad are located at the boundary of the resonance effective region, which can reflect the acoustic wave at the edge of the resonance device back to the effective resonance region, and improve the Q value of the device.
  • FIG. 1 is a front cross-sectional view of a thin film bulk acoustic wave device according to a first embodiment of the present disclosure.
  • FIG. 2 is a top view of the thin film bulk acoustic wave device according to the first embodiment of the present disclosure.
  • FIG 3 is a front cross-sectional view of a thin film bulk acoustic wave device according to a second embodiment of the present disclosure.
  • FIG. 4 is a front cross-sectional view of a thin film bulk acoustic wave device according to a third embodiment of the present disclosure.
  • FIG. 5 is a front cross-sectional view of a thin film bulk acoustic wave device according to a fourth embodiment of the present disclosure.
  • FIG. 6 is a flowchart of a method for manufacturing a thin film bulk acoustic wave device of the present disclosure.
  • FIGS. 7a-7h are schematic diagrams of the manufacturing process of the thin film bulk acoustic wave device of the present disclosure.
  • the present disclosure provides a thin film bulk acoustic resonator, including:
  • a center pillar structure is formed at an eccentric position of the thin film bulk acoustic resonator, and a cavity is formed around the center pillar structure.
  • the thin film bulk acoustic resonator of the present disclosure reduces the influence of external stress on the resonance frequency of the device, and is suitable for applications requiring higher frequency stability.
  • the piezoelectric stack structure includes: a lower electrode layer, an upper electrode layer, and a piezoelectric layer located between the lower electrode layer and the upper electrode layer; the lower electrode layer and the substrate enclose the Cavity.
  • the center pillar structure is a pillar-shaped structure that supports the bulk acoustic wave resonator, and includes: a portion of the upper electrode layer perpendicular to the substrate, and a portion of the spacer layer perpendicular to the substrate, A portion of the piezoelectric layer perpendicular to the substrate, and a portion of the lower electrode layer perpendicular to the substrate and close to the spacer layer.
  • the thin film bulk acoustic resonator may further include a conductive layer formed between the substrate and the lower electrode layer, and the cavity is formed between the lower electrode layer and the conductive layer.
  • the lower electrode layer includes a first lower electrode and a second lower electrode;
  • the first lower electrode includes a first part, a second part, a third part, and a fourth part connected in sequence, wherein the first and fourth parts are The substrate is in contact, and the first portion and the third portion extend in a direction parallel to the substrate, and the second portion and the fourth portion extend in a direction perpendicular to the substrate;
  • the second lower electrode includes Connected first, second, third, fourth and fifth parts, wherein the first and fifth parts of the second lower electrode are in contact with the substrate and the second lower electrode
  • the first portion, the third portion, and the fifth portion of the electrode extend in a direction parallel to the substrate, and the second portion and the fourth portion of the second lower electrode extend in a direction perpendicular to the substrate.
  • the piezoelectric layer includes a first piezoelectric film and a second piezoelectric film, the first piezoelectric film completely covers the fourth portion of the first lower electrode and completely or partially covers the third portion of the first lower electrode;
  • the second piezoelectric film partially covers the first part of the second lower electrode, completely covers the second part of the second lower electrode, and completely or partially covers the third part of the second lower electrode.
  • the upper electrode layer includes: a first portion extending in a direction perpendicular to the substrate, the bottom of which is in contact with the substrate and the first portion of the second lower electrode at the same time, and the first portion of the upper electrode layer is located at Between the first piezoelectric film and the second piezoelectric film; the second portion, located on the piezoelectric layer, extends in a direction parallel to the substrate.
  • the thin film bulk acoustic wave resonator further includes a pad layer, which is located on the upper electrode layer and the lower electrode.
  • the pad layer is located on the second portion of the upper electrode layer (facing the portion of the upper electrode layer perpendicular to the substrate, and the portion of the spacer layer perpendicular to the substrate , The portion of the piezoelectric layer perpendicular to the substrate, the portion of the lower electrode layer perpendicular to the substrate and close to the spacer layer), on the first portion of the first lower electrode, And the fifth part of the second lower electrode partially covers the second part of the upper electrode layer, the first part of the first lower electrode, and the fifth part of the second lower electrode. If the center pillar is wider, the upper electrode does not completely cover the first portion of the second lower electrode, and the pad layer may also be in contact with the first portion of the second lower electrode to further reduce resistance loss.
  • the spacer layer includes a first spacer film and a second spacer film; the first spacer film is located between the first piezoelectric film and the upper electrode layer, and the bottom is in contact with the substrate; the first The second spacer film is located between the second piezoelectric film and the upper electrode layer, and the bottom is in contact with the first portion of the second lower electrode; or the first spacer film is located between the first lower electrode and the Between the first piezoelectric film, and the bottom is in contact with the substrate; the second spacer film is located between the second lower electrode and the second piezoelectric film, and the bottom and the second lower film The first part of the electrode is in contact.
  • the thin film bulk acoustic wave resonator may further include a first protrusion and a second protrusion; the first protrusion is located between the upper electrode layer and the first piezoelectric film, and is located on the upper electrode layer One end of the second part; or the first protrusion is located between the first piezoelectric film and the third part of the first lower electrode and at one end of the first piezoelectric film; the second The protrusion is located between the upper electrode layer and the second piezoelectric film, and is located at the other end of the second portion of the upper electrode layer; or the second protrusion is located between the second piezoelectric film and Between the third portion of the second lower electrode and at one end of the second piezoelectric film.
  • FIG. 1 is a front cross-sectional view of a thin film bulk acoustic wave device according to a first embodiment of the present disclosure.
  • the thin film bulk acoustic wave device of this embodiment includes a substrate 1, a sacrificial layer 2, a lower electrode layer 3, a piezoelectric layer 4, a spacer layer 5, an upper electrode layer 6 and a pad 9.
  • the sacrificial layer of the thin film bulk acoustic wave device of the present disclosure will be etched out lastly, that is, the thin film bulk acoustic wave device finally produced does not include the sacrificial layer, and the sacrificial layer region correspondingly forms the cavity region, so the The device supported by the pillar.
  • the thin film bulk acoustic wave device of this embodiment has a disk-like shape and resonates through a sandwich structure of an upper electrode layer-piezoelectric layer-lower electrode layer.
  • FIG. 2 is a top view of the thin film bulk acoustic wave device according to the first embodiment of the present disclosure.
  • the lower electrode layer is etched into a first lower electrode 31 and a second lower electrode 32.
  • the first lower electrode 31 is led out through the edge portion, and the upper electrode layer is connected to the second lower electrode 32 through the center pillar, so that it is led out through the edge, which helps reduce the effect of external stress on the device, thereby reducing the frequency offset.
  • the first lower electrode 31 includes a first part 311, a second part 312, a third part 313, and a fourth part 314 connected in sequence, wherein the first part and the fourth part are in contact with the substrate, and the first part and the third part
  • the three parts extend in a direction parallel to the substrate, and the second and fourth parts extend in a direction perpendicular to the substrate.
  • the second lower electrode 32 includes a first part 321, a second part 322, a third part 323, a fourth part 324, and a fifth part 325 connected in sequence, wherein the first and fifth parts of the second lower electrode In contact with the substrate, and the first, third, and fifth portions of the second lower electrode extend in a direction parallel to the substrate, and the second and fourth portions of the second lower electrode It extends in a direction perpendicular to the substrate.
  • the piezoelectric layer 4 includes a first piezoelectric film 41 and a second piezoelectric film 42.
  • the first piezoelectric film completely covers the fourth portion of the first lower electrode and partially covers the third portion of the first lower electrode.
  • the second piezoelectric film partially covers the first portion of the second lower electrode, completely covers the second portion of the second lower electrode, and partially covers the third portion of the second lower electrode.
  • the upper electrode layer 6 includes a first part 61 and a second part 62.
  • the first portion 61 extends in a direction perpendicular to the substrate, the bottom thereof is in contact with the substrate and the first portion of the second lower electrode at the same time, and the first portion of the upper electrode layer is located on the first piezoelectric Between the film and the second piezoelectric film.
  • the second portion 62 is located on the piezoelectric layer and extends in a direction parallel to the substrate.
  • the thin film bulk acoustic wave resonator further includes a spacer layer 5 including a first spacer film 51 and a second spacer film 52.
  • the first spacer film is located between the first piezoelectric film and the upper electrode layer, and the bottom is in contact with the substrate; the second spacer film is located on the second piezoelectric film and the upper Between the electrode layers, and the bottom is in contact with the first portion of the second lower electrode.
  • the thin-film bulk acoustic wave resonator further includes a pad layer 9 including a first pad 91, a second pad 92 and a third pad 93, the pad layer being located at the first position of the upper electrode layer Two parts of the upper part, the first part of the first lower electrode and the fifth part of the second lower electrode, partially covering the second part of the upper electrode layer, the first part of the first lower electrode and the fifth part of the second lower electrode section.
  • the thin film bulk acoustic wave resonator further includes a convex structure, and the convex structure includes a first projection 81 and a second projection 82.
  • the first protrusion is located between the upper electrode and the first piezoelectric film and at one end of the second portion of the upper electrode layer.
  • the second protrusion is located between the upper electrode layer and the second piezoelectric film and at the other end of the second portion of the upper electrode layer.
  • the center pillar structure includes: a portion 61 of the upper electrode layer perpendicular to the substrate, a portion of the spacer layer perpendicular to the substrate, and a piezoelectric layer perpendicular to the substrate Part, and a part of the lower electrode layer perpendicular to the substrate and close to the spacer layer (ie, a fourth part of the first lower electrode).
  • the material of the substrate is silicon or a material with low thermal conductivity;
  • the material of the sacrificial layer includes but is not limited to silicon dioxide, silicon phosphorous glass (PSG), etc.;
  • the material of the lower electrode layer and the upper electrode layer is Conductive materials, such as aluminum, molybdenum, copper, gold, platinum, silver, nickel, chromium, tungsten, etc. compatible with semiconductor processes;
  • materials of the piezoelectric layer include but are not limited to aluminum nitride, oxidizing, etc.;
  • the material of the layer is a dielectric material, such as PSG, or other materials that are not easily etched;
  • the pad is a highly conductive material, such as aluminum, copper, gold, platinum, silver, nickel, chromium, etc. compatible with semiconductor processes.
  • the effective resonance area of the resonator is located in the area where the upper electrode and the lower electrode face each other.
  • a spacer layer is introduced to reduce the influence of the parasitic capacitance of the upper and lower electrodes in this area, while isolating the upper and lower electrodes. In this way, no resonance occurs in the area of the center pillar, and the displacement is small, thereby reducing the transmission of external forces into the device.
  • the spacer layer also naturally forms a convex structure 8 at the edge of the resonance effective area (the convex structure is the same material as the spacer layer), which can reflect the acoustic wave of the resonance device at the edge back to the effective area and improve the Q value of the device.
  • the position O of the center pillar is deviated from the center of the disc, whereby the resonance caused by the lateral mode is suppressed, improving the performance of the filter and the oscillator.
  • FIG 3 is a front cross-sectional view of a thin film bulk acoustic wave device according to a second embodiment of the present disclosure. Different from the first embodiment, this embodiment first grows a conductive layer 7 (the material is similar to the lower electrode) on the substrate, and then grows the subsequent layers similar to the first embodiment.
  • a conductive layer 7 the material is similar to the lower electrode
  • the first lower electrode of the device includes two parts, one of which is parallel to the substrate and the other is perpendicular to the substrate; the second lower electrode includes a part that is parallel to the substrate ;
  • the lower electrode and the upper electrode of the device are led out through the first conductive film 71 and the second conductive film 72 of the conductive layer, respectively, therefore, the device is completely supported by the center pillar, further reducing the lead caused by the lead wire in the first embodiment Stress effect.
  • the reliability of the device may be worse than the structure of the first embodiment.
  • the center pillar structure includes: a portion 61 of the upper electrode layer perpendicular to the substrate, a portion of the spacer layer perpendicular to the substrate, and a portion of the piezoelectric layer A portion of the substrate perpendicular to the substrate, and a portion of the lower electrode layer perpendicular to the substrate and close to the spacer layer.
  • FIG. 4 is a front cross-sectional view of a thin film bulk acoustic wave device according to a third embodiment of the present disclosure.
  • the difference from the first embodiment is that after etching the piezoelectric layer, the piezoelectric layer is not retained in the center pillar region. This can further reduce the influence of parasitic capacitance in the center pillar area.
  • the spacer layer is located between the upper electrode and the piezoelectric layer, while in the fourth embodiment, the spacer layer may be located between the lower electrode and the piezoelectric layer.
  • the raised structure of the edge can also reflect the sound wave of the resonant device at the edge back to the effective area, and improve the Q value of the device.
  • the device structure of the present disclosure is not limited to the shape of a disk, and may be an ellipse, a pentagon, or other irregular polygons, but it should be avoided as a regular polygon, which can also reduce the resonance effect of the lateral mode.
  • FIGS. 6 and 7a-7g are schematic diagrams of the manufacturing process of the thin film bulk acoustic wave device according to the second embodiment of the present disclosure. As shown in FIGS. 6 and 7a-7g, the specific manufacturing process of the film bulk acoustic wave device is as follows:
  • a conductive layer is deposited on the surface of the substrate and patterned, and the conductive layer is divided into a first conductive film and a second conductive film, which are used to lead out the lower electrode and the upper electrode of the device, respectively;
  • a sacrificial layer is deposited on the substrate, covering the conductive layer, and the sacrificial layer is patterned to define the position of the center pillar. A part of the conductive layer needs to be exposed in the center pillar area for electrical connection later;
  • the lower electrode layer is deposited and also patterned; the lower electrode layer is left with holes in the center pillar area, and the lower electrode layer is connected to the first conductive film of the conductive layer; before the lower electrode layer is deposited, Generally, a thin isolation layer is grown to isolate oxygen migration from the sacrificial layer to the lower electrode layer.
  • a temperature compensation layer can also be selectively inserted or grown on the surface of the lower electrode layer.
  • the temperature compensation layer material is a material with a positive temperature coefficient such as silicon dioxide or PSG;
  • a piezoelectric layer is deposited and patterned to expose the conductive layer at the edge and center pillar area for the extraction of the upper electrode;
  • a spacer layer is deposited to expose the edge and center pillar area.
  • the spacer layer pattern is retained in the edge area of the disk to form a convex structure, which can reflect the acoustic wave of the resonance device at the edge back to the effective resonance area and improve the Q value of the device;
  • the upper electrode layer is deposited and patterned.
  • the upper electrode is led out through the second conductive film of the conductive layer (as shown).
  • the device forms an effective resonance area from the area directly facing the upper electrode and the lower electrode.
  • a passivation layer is generally grown on the surface of the upper electrode layer to protect the electrode from corrosion;
  • the pad layer is deposited and patterned.
  • the pad includes a first pad on the upper electrode layer, a second pad on the first part of the first lower electrode, and a third pad on the fifth part or the first part of the second lower electrode .
  • the pad structure of the present disclosure can reduce the connection resistance, and at the same time the first pad is located in the center pillar area, which can strengthen the center pillar structure.
  • the two ends of the first pad are located at the boundary of the resonance effective region, which can reflect the acoustic wave at the edge of the resonance device back to the effective resonance region, and improve the Q value of the device;
  • the device is placed in an etching solution, the sacrificial layer is etched away, and the device is released. Finally, the device is only supported by the center pillar structure, which can reduce the effect of external stress on the device.
  • the process of the present disclosure is relatively simple, does not require chemical mechanical polishing (CMP) treatment of the sacrificial layer, and can also reduce the number of grown material layers, which reduces the manufacturing cost.
  • CMP chemical mechanical polishing
  • the present disclosure also provides a filter including a plurality of the thin film bulk acoustic resonators cascaded.
  • the method of the present invention also includes other steps. Since it is not related to the innovation of the present invention, it will not be repeated here.

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Abstract

一种薄膜体声波谐振器及其制作方法、滤波器；其中，所述薄膜体声波谐振器，包括：衬底（1），以及压电堆叠结构，形成于所述衬底（1）上；其中，在所述薄膜体声波谐振器的偏心位置形成有中柱结构，在所述中柱结构的周围形成有空腔。所述薄膜体声波谐振器降低了外界应力对器件的谐振频率的影响，适用于较高频率稳定性要求的应用。

Description

薄膜体声波谐振器及其制作方法、滤波器 技术领域
本公开属于无线通讯技术领域，更具体地涉及一种薄膜体声波谐振器及其制作方法、滤波器。
背景技术
薄膜体声波谐振器(FBAR)依靠高Q值，较大的耦合系数等优势，应用于现今的射频滤波器和振荡器中。
振荡器面临的一个主要问题是，外界的应力传递到谐振器，使得谐振频率发生变化，进而影响振荡器的中心频率。比如由FBAR制作的振荡器，一般会把FBAR贴装于包含金属和层压介质的印刷电路板(PCB)上。当PCB受热或者降温时，PCB板会发生形变，产生的应力传递到FBAR，导致谐振频率变化。变化的频率虽小，但比老化等因素导致的频偏更严重，而且很难去量化。
对于高精度电子领域的应用，外力所导致的频偏是的器件很难满足要求。比如GPS器件要求频率偏移控制在±0.5ppm，Wifi和蓝牙等无线应用也只允许频偏在因此±10ppm内。因此，减小外界应力对声波谐振器频率的影响显得尤为重要。
然而，现有的薄膜体声波及滤波器、振荡器普遍生长的材料层数较多，工艺较为复杂，外界应力易传递到谐振器件，频偏严重，无法有效减小外界应力对声波谐振器频率的影响。
发明内容
(一)要解决的技术问题
本公开提供了一种薄膜体声波谐振器及其制作方法、滤波器，以至少部分解决以上所存在的技术问题。
(二)技术方案
根据本公开的一个方面，提供了一种薄膜体声波谐振器，包括：
衬底，以及
压电堆叠结构，形成于所述衬底上；
其中，在所述薄膜体声波谐振器的偏心位置形成有中柱结构，在所述中柱结构的周围形成有空腔。
在一些实施例中，所述压电堆叠结构包括下电极层、上电极层以及位于所述下电极层和上电极层之间的压电层；所述下电极和所述衬底围成所述空腔。
在一些实施例中，所述压电堆叠结构包括下电极层、上电极层以及位于所述下电极层和上电极层之间的压电层；所述薄膜体声波谐振器还包括形成于所述衬底与所述下电极层之间的导电层，在所述下电极和所述导电层之间形成所述空腔。
在一些实施例中，所述下电极层包括第一下电极和第二下电极；
所述第一下电极包括依次相连的第一部分、第二部分、第三部分及第四部分，其中，第一部分和第四部分与所述衬底接触，且第一部分和第三部分沿平行于所述衬底的方向延伸，第二部分和第四部分沿垂直于所述衬底的方向延伸；
所述第二下电极包括依次相连的第一部分、第二部分、第三部分、第四部分及第五部分，其中，所述第二下电极的第一部分和第五部分与所述衬底接触，且所述第二下电极的第一部分、第三部分和第五部分沿平行于所述衬底的方向延伸，所述第二下电极的第二部分和第四部分沿垂直于所述衬底的方向延伸。
在一些实施例中，所述压电层包括第一压电膜和第二压电膜，所述第一压电膜完全覆盖第一下电极的第四部分且完全覆盖或者部分覆盖第一下电极的第三部分；
所述第二压电膜部分覆盖所述第二下电极的第一部分，完全覆盖所述第二下电极的第二部分，且完全覆盖或者部分覆盖第二下电极的第三部分。
在一些实施例中，所述上电极层包括：
第一部分，沿垂直于衬底的方向延伸，其底部同时与所述衬底及所述第二下电极的第一部分接触，且所述上电极层的第一部分位于所述第一压电膜与第二压电膜之间；
第二部分，位于所述压电层上，沿平行于所述衬底的方向延伸。
在一些实施例中，所述的薄膜体声波谐振器，还包括间隔层，该间隔层包括第一间隔膜和第二间隔膜；
所述第一间隔膜位于所述第一压电膜和所述上电极层之间，且底部与所述衬底接触；所述第二间隔膜位于所述第二压电膜和所述上电极层之间，且底部与所述第二下电极的第一部分接触；或
所述第一间隔膜位于所述第一下电极和所述第一压电膜之间，且底部与所述衬底接触；所述第二间隔膜位于所述第二下电极与所述第二压电膜之间，且底部与所述第二下电极的第一部分接触。
在一些实施例中，所述的薄膜体声波谐振器，还包括第一凸起和第二凸起；
第一凸起位于所述上电极层与所述第一压电膜之间、且位于所述上电极层的第二部分的其中一端部；或第一凸起位于所述第一压电膜与第一下电极的第三部分之间、且位于所述第一压电膜的一端部；
所述第二凸起位于所述上电极层与所述第二压电膜之间、且位于所述上电极层的第二部分的其中另一端部；或第二凸起位于所述第二压电膜与第二下电极的第三部分之间、且位于所述第二压电膜的一端部。
在一些实施例中，所述的薄膜体声波谐振器，还包括焊盘层，位于所述上电极层及所述下电极层上。
在一些实施例中，所述焊盘层部分覆盖所述上电极层的第二部分、所述第一下电极的第一部分、及所述第二下电极的第五部分或第一部分。
在一些实施例中，所述导电层包括第一导电膜和第二导电膜；
所述下电极层包括第一下电极和第二下电极；所述第一下电极包括相连的第一部分和第二部分；第一下电极的第一部分沿着平行于衬底的方向延伸，第一下电极的第二部分沿着垂直于衬底的方向延伸，且与所述衬底接触，所述第一下电极的第一部分与所述第一导电膜之间具有一间隙；第二下电极沿平行于所述衬底的方向延伸，且与所述第二导电膜之间具有一间隙。
在一些实施例中，所述压电层包括第一压电膜和第二压电膜，所述第一压电膜完全覆盖第一下电极的第一部分和第二部分；所述第二压电膜完全覆盖所述第二下电极。
在一些实施例中，所述上电极层包括：第一部分，沿垂直于衬底的方向延伸，其底部同时与所述衬底及所述第二导电膜接触，且所述上电极层的第一部分位于所述第一压电膜与第二压电膜之间；以及第二部分，位于所述压电层上，沿平行于所述衬底的方向延伸。
在一些实施例中，所述薄膜体声波谐振器还包括间隔层，该间隔层包括第一间隔膜和第二间隔膜；所述第一间隔膜位于所述第一压电膜和所述上电极层之间，且底部与所述衬底接触；所述第二间隔膜位于所述第二压电膜和所述上电极层之间，且底部与所述第二导电膜接触。
在一些实施例中，所述压电层包括第一压电膜和第二压电膜，第一压电膜形成于所述第一下电极的第三部分上，第二压电膜形成于所述第二下电极的第三部分上。
在一些实施例中，所述上电极层包括：第一部分，沿垂直于衬底的方向延伸，其底部同时与所述衬底及所述第二下电极的第一部分接触，且所述上电极层的第一部分位于所述第一压电膜与第二压电膜之间且位于所第一下电极的第四部分与所述第二下电极的第二部分之间；以及第二部分，位于所述压电层上，沿平行于所述衬底的方向延伸。
在一些实施例中，所述的薄膜体声波谐振器，还包括间隔层，该间隔层包括第一间隔膜和第二间隔膜；所述第一间隔膜的底部与所述衬底接触，且完全覆盖所述第一下电极的第四部分、部分覆盖所述第一下电极的第三部分及部分覆盖所述第一压电膜；所述第一间隔膜的底部与所述第二下电极的第一部分接触，且完全覆盖所述第二下电极的第二部分、部分覆盖所述第二下电极的第三部分及部分覆盖所述第二压电膜。
在一些实施例中，所述中柱结构包括：所述上电极层的与所述衬底垂直的部分，所述间隔层的与所述衬底垂直的部分，所述压电层的与所述衬底垂直的部分，所述下电极层的与所述衬底垂直、且靠近所述间隔层的部分。
根据本公开的另一个方面，还提供了一种薄膜体声波谐振器的制作方法，包括：
在衬底上生长牺牲层并图形化处理，形成第一开口区域；
生长下电极层并刻蚀下电极层，在所述第一开口区域内形成第二开口区域；
生长压电层和上电极层；
刻蚀上电极层，并刻蚀压电层，在所述第二开口区域内形成第三开口区域；
刻蚀去除所述牺牲层，在所述下电极与所述衬底之间、所述薄膜体声波谐振器的有效谐振区域形成空腔。
在一些实施例中，所述的薄膜体声波谐振器的制作方法，还包括：在所述下电极层与所述压电层之间或所述压电层与所述压电层与所述上电极层之间生长隔离层，并作图像化处理。
在一些实施例中，在生长牺牲层之前，还包括：生长导电层并作图像化处理。
在一些实施例中，所述的薄膜体声波谐振器的制作方法，还包括：在所述下电极层与所述压电层或所述压电层与所述上电极之间形成凸起结构。
根据本公开的另一个方面，还提供了一种滤波器，其包括级联的多个所述薄膜体声波谐振器。
(三)有益效果
从上述技术方案可以看出，本公开一种薄膜体声波谐振器及其制作方法、滤波器至少具有以下有益效果其中之一：
(1)本公开降低了外界应力对器件的谐振频率的影响，适用于较高频率稳定性要求的应用。
(2)本公开工艺相对简单，不需要对牺牲层做化学机械抛光(CMP)处理，也可以减少生长的材料层数，这都降低了制作成本
(3)本公开焊盘结构可以减小连接电阻，同时第一焊盘位于中柱区域，可以加固中柱结构。此外，第一焊盘的两端位于谐振有效区的边界，可以将谐振器件在边缘处的声波反射回有效谐振区域，提高器件的Q值。
附图说明
为了更清楚地说明本发明具体实施方式或现有技术中的技术方案，下面将对具体实施方式或现有技术描述中所需要使用的附图作简单地介绍， 显而易见地，下面描述中的附图是本发明的一些实施方式，对于本领域普通技术人员来讲，在不付出创造性劳动的前提下，还可以根据这些附图获得其他的附图。
图1为本公开第1实施例薄膜体声波器的正面剖视图。
图2为本公开第1实施例薄膜体声波器的俯视图。
图3为本公开第2实施例薄膜体声波器的正面剖视图。
图4为本公开第3实施例薄膜体声波器的正面剖视图。
图5为本公开第4实施例薄膜体声波器的正面剖视图。
图6为本公开薄膜体声波器制作方法流程图。
图7a-图7h为本公开薄膜体声波器制作过程示意图。
<符号说明>
1-衬底；2-牺牲层(牺牲层区域对应空腔区域)；3-下电极层；31-第一下电极，32-第二下电极；311-314分别为第一下电极的第一部分至第四部分；321-325分别为第二下电极的第一部分至第五部分；4-压电层；41-第一压电膜，42-第二压电膜；5-间隔层；51-第一间隔膜，52-第二间隔膜；6-上电极层；61-上电极层的第一部分，62-上电极层的第二部分；7-导电层；71-第一导电膜，72-第二导电膜；8-凸起结构；81-第一凸起，82-第二凸起；9-焊盘层；91-第一焊盘、92-第二焊盘、93-第三焊盘；O-中柱位置。
具体实施方式
为使本发明的目的、技术方案和优点更加清楚明白，以下结合具体实施例，并参照附图，对本发明进一步详细说明。
本公开提供了一种薄膜体声波谐振器，包括：
衬底，以及
压电堆叠结构，形成于所述衬底上；
其中，在所述薄膜体声波谐振器的偏心位置形成有中柱结构，在所述中柱结构的周围形成有空腔。
本公开薄膜体声波谐振器降低了外界应力对器件的谐振频率的影响，适用于较高频率稳定性要求的应用。
具体的，所述压电堆叠结构包括：下电极层、上电极层以及位于所述下电极层和上电极层之间的压电层；所述下电极层和所述衬底围成所述空腔。
所述中柱结构为体声波谐振器中起支撑作用的柱形结构，包括：所述上电极层的与所述衬底垂直的部分，所述间隔层的与所述衬底垂直的部分，所述压电层的与所述衬底垂直的部分，所述下电极层的与所述衬底垂直、且靠近所述间隔层的部分。
进一步的，所述薄膜体声波谐振器还可包括形成于所述衬底与所述下电极层之间的导电层，在所述下电极层和所述导电层之间形成所述空腔。
所述下电极层包括第一下电极和第二下电极；所述第一下电极包括依次相连的第一部分、第二部分、第三部分及第四部分，其中，第一部分和第四部分与所述衬底接触，且第一部分和第三部分沿平行于所述衬底的方向延伸，第二部分和第四部分沿垂直于所述衬底的方向延伸；所述第二下电极包括依次相连的第一部分、第二部分、第三部分、第四部分及第五部分，其中，所述第二下电极的第一部分和第五部分与所述衬底接触，且所述第二下电极的第一部分、第三部分和第五部分沿平行于所述衬底的方向延伸，所述第二下电极的第二部分和第四部分沿垂直于所述衬底的方向延伸。
所述压电层包括第一压电膜和第二压电膜，所述第一压电膜完全覆盖第一下电极的第四部分且完全覆盖或者部分覆盖第一下电极的第三部分；所述第二压电膜部分覆盖所述第二下电极的第一部分，完全覆盖所述第二下电极的第二部分，且完全覆盖或者部分覆盖第二下电极的第三部分。
所述上电极层包括：第一部分，沿垂直于衬底的方向延伸，其底部同时与所述衬底及所述第二下电极的第一部分接触，且所述上电极层的第一部分位于所述第一压电膜与第二压电膜之间；第二部分，位于所述压电层上，沿平行于所述衬底的方向延伸。
所述的薄膜体声波谐振器还包括焊盘层，位于所述上电极层及所述下电极上。具体的，所述焊盘层位于所述上电极层的第二部分上(正对所述上电极层的与所述衬底垂直的部分，所述间隔层的与所述衬底垂直的部分，所述压电层的与所述衬底垂直的部分，所述下电极层的与所述衬底垂直、 且靠近所述间隔层的部分)、所述第一下电极的第一部分上、及所述第二下电极的第五部分上，部分覆盖所述上电极层的第二部分、所述第一下电极的第一部分、及所述第二下电极的第五部分。如果中柱较宽，上电极未全部覆盖第二下电极的第一部分，焊盘层与第二下电极的第一部分也可接触，以进一步降低电阻损耗。
所述间隔层包括第一间隔膜和第二间隔膜；所述第一间隔膜位于所述第一压电膜和所述上电极层之间，且底部与所述衬底接触；所述第二间隔膜位于所述第二压电膜和所述上电极层之间，且底部与所述第二下电极的第一部分接触；或所述第一间隔膜位于所述第一下电极和所述第一压电膜之间，且底部与所述衬底接触；所述第二间隔膜位于所述第二下电极与所述第二压电膜之间，且底部与所述第二下电极的第一部分接触。
所述的薄膜体声波谐振器还可包括第一凸起和第二凸起；第一凸起位于所述上电极层与所述第一压电膜之间、且位于所述上电极层的第二部分的其中一端部；或第一凸起位于所述第一压电膜与第一下电极的第三部分之间、且位于所述第一压电膜的一端部；所述第二凸起位于所述上电极层与所述第二压电膜之间、且位于所述上电极层的第二部分的其中另一端部；或第二凸起位于所述第二压电膜与第二下电极的第三部分之间、且位于所述第二压电膜的一端部。
图1为本公开第1实施例薄膜体声波器的正面剖视图。如图1所示，本实施例薄膜体声波器包括：衬底1、牺牲层2、下电极层3、压电层4、间隔层5、上电极层6及焊盘9。
其中，本公开薄膜体声波器的所述牺牲层最后会被刻蚀掉，也即最终制作而成的薄膜体声波器不包括牺牲层，牺牲层区域相应的形成空腔区域，因此形成由中间支柱支撑的器件。本实施例薄膜体声波器具备类似圆盘的形状，通过上电极层-压电层-下电极层的三明治结构谐振。
图2为本公开第1实施例薄膜体声波器的俯视图。如图1-2所示，所述下电极层被刻蚀成第一下电极31和第二下电极32。其中第一下电极31通过边缘部分引出，而上电极层通过中柱与第二下电极32连接，从而通过边缘引出，有助于降低外界应力对器件的作用，从而减小频率的偏移。
所述第一下电极31包括依次相连的第一部分311、第二部分312、第三部分313及第四部分314，其中，第一部分和第四部分与所述衬底接触，且第一部分和第三部分沿平行于所述衬底的方向延伸，第二部分和第四部分沿垂直于所述衬底的方向延伸。
所述第二下电极32包括依次相连的第一部分321、第二部分322、第三部分323、第四部分324及第五部分325，其中，所述第二下电极的第一部分和第五部分与所述衬底接触，且所述第二下电极的第一部分、第三部分和第五部分沿平行于所述衬底的方向延伸，所述第二下电极的第二部分和第四部分沿垂直于所述衬底的方向延伸。
所述压电层4包括第一压电膜41和第二压电膜42。所述第一压电膜完全覆盖第一下电极的第四部分、且部分覆盖第一下电极的第三部分。所述第二压电膜部分覆盖所述第二下电极的第一部分，完全覆盖所述第二下电极的第二部分，且部分覆盖第二下电极的第三部分。
所述上电极层6包括第一部分61和第二部分62。所述第一部分61沿垂直于衬底的方向延伸，其底部同时与所述衬底及所述第二下电极的第一部分接触，且所述上电极层的第一部分位于所述第一压电膜与第二压电膜之间。所述第二部分62位于所述压电层上，沿平行于所述衬底的方向延伸。
所述薄膜体声波谐振器还包括间隔层5，该间隔层包括第一间隔膜51和第二间隔膜52。所述第一间隔膜位于所述第一压电膜和所述上电极层之间，且底部与所述衬底接触；所述第二间隔膜位于所述第二压电膜和所述上电极层之间，且底部与所述第二下电极的第一部分接触。
所述薄膜体声波谐振器还包括焊盘层9，该焊盘层包括第一焊盘91，第二焊盘92和第三焊盘93，所述焊盘层位于所述上电极层的第二部分上、第一下电极的第一部分及第二下电极的第五部分之上，部分覆盖所述上电极层的第二部分、第一下电极的第一部分及第二下电极的第五部分。所述薄膜体声波谐振器还包括凸起结构，该凸起结构包括第一凸起81和第二凸起82。所述第一凸起位于所述上电极与所述第一压电膜之间、且位于所述上电极层的第二部分的其中一端部。所述第二凸起位于所述上电极层与所述第二压电膜之间、且位于所述上电极层的第二部分的其中另一端部。
所述中柱结构包括：所述上电极层的与所述衬底垂直的部分61，所述间隔层的与所述衬底垂直的部分，所述压电层的与所述衬底垂直的部分，及所述下电极层的与所述衬底垂直、且靠近所述间隔层的部分(即第一下电极的第四部分)。
所述衬底的材料为硅或者具有低热传导特性的材料；所述牺牲层的材料包括但不限于二氧化硅，硅磷玻璃(PSG)等；所述下电极层和上电极层的材料为导电材料，比如与半导体工艺兼容的铝，钼，铜，金，铂，银，镍，铬，钨等；所述压电层的材料包括但不限于氮化铝，氧化性等；所述间隔层的材料为介质材料，比如PSG，或者其它不易被刻蚀的材料；所述焊盘为高导电材料，比如与半导体工艺兼容的铝，铜，金，铂，银，镍，铬，等。
所述谐振器的有效谐振区域位于圆盘内，上电极与下电极正对的区域。而在中柱区域内，引入了间隔层，以减小该区域内上下电极寄生电容的影响，同时隔绝上下电极。如此，在中柱区域内不发生谐振，位移很小，从而减小了外界作用力传递到器件内。同时，间隔层在谐振有效区域边缘还自然形成了凸起结构8(凸起结构与间隔层材质相同)，可以将谐振器件在边缘处的声波的反射回有效区域，提高器件的Q值。
需要说明的是，如图2所示，中柱位置O偏离圆盘的中心，由此，横向模式引发的谐振受到抑制，提升了滤波器和振荡器的性能。
图3为本公开第2实施例薄膜体声波器的正面剖视图。与第1实施例不同的是，本实施例先在衬底上生长了一层导电层7(材料类似于下电极)，然后与第1实施例类似，生长随后的各层。有所不同的是，器件的第一下电极包括两个部分，其中之一与所述衬底平行，另一与所述衬底垂直；第二下电极包括一个部分，与所述衬底平行；器件的下电极和上电极分别通过导电层的第一导电膜71和第二导电膜72引出，因此，该器件完全由中柱支撑，进一步降低了第1实施例中引出线所带来的应力影响。但也正因为仅由中柱支撑，器件的可靠性可能会差于第1实施例的结构。
本实施例中，所述中柱结构包括：所述上电极层的与所述衬底垂直的部分61，所述间隔层的与所述衬底垂直的部分，所述压电层的与所述衬底 垂直的部分，及所述下电极层的与所述衬底垂直、且靠近所述间隔层的部分。
图4为本公开第3实施例薄膜体声波器的正面剖视图。与第1实施例不同的是，对压电层作刻蚀后，在中柱区域内未保留压电层。这样可进一步减小中柱区域内寄生电容的影响。
图5为本公开第4实施例薄膜体声波器的正面剖视图。在第1实施例中，间隔层位于上电极与压电层之间，而在第4实施例中，间隔层也可位于下电极与压电层之间。边缘的凸起结构同样可以将谐振器件在边缘处的声波的反射回有效区域，提高器件的Q值。
当然，本公开器件结构并不限于圆盘形状，可以是椭圆形，五边形或其他不规则多边形，但应避免为正多边形，这样同样可以降低横向模式的谐振影响。
图6为本公开第2实施例薄膜体声波器制作方法流程图。图7a-图7g为本公开第2实施例薄膜体声波器制作过程示意图。如图6及图7a-7g所示，所述薄膜体声波器具体制作过程如下：
如图7a所示，首先在衬底表面沉积导电层，图形化处理，将导电层分为第一导电膜和第二导电膜，用来分别引出器件的下电极和上电极；
如图7b所示，在衬底上沉积牺牲层，覆盖导电层，并图形化牺牲层，定义出中柱位置。在中柱区域需要露出一部分导电层以便之后作电连接；
如图7c所示，沉积下电极层，同样作图形化处理；使下电极层在中柱区域留出孔，并且下电极层与导电层的第一导电膜相连；在沉积下电极层之前，一般会先生长一层薄的隔离层，隔绝牺牲层到下电极层间的氧迁移。另外，也可以选择性的在下电极层内插入或者表面生长一层温度补偿层，温度补偿层材料为二氧化硅或者PSG等具有正温度系数的材料；
如图7d所示，沉积压电层，并作图形化处理，露出边缘和中柱区域的导电层，以便上电极的引出；
如图7e所示，沉积间隔层，露出边缘和中柱区域。同时在圆盘边缘区域保留间隔层图形，形成的凸起结构，可以将谐振器件在边缘处的声波反射回有效谐振区域，提高器件的Q值；
如图7f所示，沉积上电极层，作图形化处理。上电极通过导电层的第 二导电膜引出(如图所示)。一旦上电极形成，器件由上电极和下电极的正对区域形成有效谐振区域。另外，一般会在上电极层表面生长钝化层，保护电极不被腐蚀；
如图7g所示，沉积焊盘层，作图形化处理。所述焊盘包括位于上电极层之上的第一焊盘、第一下电极的第一部分之上的第二焊盘及第二下电极的第五部分或第一部分之上的第三焊盘。本公开焊盘结构可以减小连接电阻，同时第一焊盘位于中柱区域，可以加固中柱结构。此外，第一焊盘的两端位于谐振有效区的边界，可以将谐振器件在边缘处的声波反射回有效谐振区域，提高器件的Q值；
如图7h所示，将器件置于腐蚀液中，牺牲层被刻蚀掉，释放器件。最后，器件仅由中柱结构支撑，可减小外界应力对器件的作用。
本公开工艺相对简单，不需要对牺牲层做化学机械抛光(CMP)处理，也可以减少生长的材料层数，这都降低了制作成本。
此外，本公开还提供了一种滤波器，其包括级联的多个所述薄膜体声波谐振器。
以上所述的具体实施例，对本发明的目的、技术方案和有益效果进行了进一步详细说明，所应理解的是，以上所述仅为本发明的具体实施例而已，并不用于限制本发明，凡在本发明的精神和原则之内，所做的任何修改、等同替换、改进等，均应包含在本发明的保护范围之内。
当然，根据实际需要，本发明方法还包含其他的步骤，由于同本发明的创新之处无关，此处不再赘述。
此外，上述对各元件和方法的定义并不仅限于实施例中提到的各种具体结构、形状或方式，本领域普通技术人员可对其进行简单地更改或替换。
需要说明的是，实施例中提到的方向用语，例如“上”、“下”、“前”、“后”、“左”、“右”等，仅是参考附图的方向，并非用来限制本发明的保护范围。贯穿附图，相同的元素由相同或相近的附图标记来表示。在可能导致对本发明的理解造成混淆时，将省略常规结构或构造。并且图中各部件的形状和尺寸不反映真实大小和比例，而仅示意本发明实施例的内容。另外，在权利要求中，不应将位于括号之间的任何参考符号构造成对权利要求的限制。
再者，单词“包含”或“包括”不排除存在未列在权利要求中的元件或步骤。位于元件之前的单词“一”或“一个”不排除存在多个这样的元件。
说明书与权利要求中所使用的序数例如“第一”、“第二”、“第三”等的用词，以修饰相应的元件，其本身并不意味着该元件有任何的序数，也不代表某一元件与另一元件的顺序、或是制造方法上的顺序，该些序数的使用仅用来使具有某命名的一元件得以和另一具有相同命名的元件能做出清楚区分。
以上所述的具体实施例，对本发明的目的、技术方案和有益效果进行了进一步详细说明，所应理解的是，以上所述仅为本发明的具体实施例而已，并不用于限制本发明，凡在本发明的精神和原则之内，所做的任何修改、等同替换、改进等，均应包含在本发明的保护范围之内。

Claims (23)

  1. 一种薄膜体声波谐振器，包括：
    衬底，以及
    压电堆叠结构，形成于所述衬底上；
    其中，在所述薄膜体声波谐振器的偏心位置形成有中柱结构，在所述中柱结构的周围形成有空腔。
  2. 根据权利要求1所述的薄膜体声波谐振器，其中，所述压电堆叠结构包括下电极层、上电极层以及位于所述下电极层和上电极层之间的压电层；所述下电极和所述衬底围成所述空腔。
  3. 根据权利要求1所述的薄膜体声波谐振器，其中，所述压电堆叠结构包括下电极层、上电极层以及位于所述下电极层和上电极层之间的压电层；所述薄膜体声波谐振器还包括形成于所述衬底与所述下电极层之间的导电层，在所述下电极和所述导电层之间形成所述空腔。
  4. 根据权利要求2所述的薄膜体声波谐振器，其中，
    所述下电极层包括第一下电极和第二下电极；
    所述第一下电极包括依次相连的第一部分、第二部分、第三部分及第四部分，其中，第一部分和第四部分与所述衬底接触，且第一部分和第三部分沿平行于所述衬底的方向延伸，第二部分和第四部分沿垂直于所述衬底的方向延伸；
    所述第二下电极包括依次相连的第一部分、第二部分、第三部分、第四部分及第五部分，其中，所述第二下电极的第一部分和第五部分与所述衬底接触，且所述第二下电极的第一部分、第三部分和第五部分沿平行于所述衬底的方向延伸，所述第二下电极的第二部分和第四部分沿垂直于所述衬底的方向延伸。
  5. 根据权利要求4所述的薄膜体声波谐振器，其中，
    所述压电层包括第一压电膜和第二压电膜，所述第一压电膜完全覆盖第一下电极的第四部分且完全覆盖或者部分覆盖第一下电极的第三部分；
    所述第二压电膜部分覆盖所述第二下电极的第一部分，完全覆盖所述第二下电极的第二部分，且完全覆盖或者部分覆盖第二下电极的第三部分。
  6. 根据权利要求5所述的薄膜体声波谐振器，其中，所述上电极层包括：
    第一部分，沿垂直于衬底的方向延伸，其底部同时与所述衬底及所述第二下电极的第一部分接触，且所述上电极层的第一部分位于所述第一压电膜与第二压电膜之间；
    第二部分，位于所述压电层上，沿平行于所述衬底的方向延伸。
  7. 根据权利要求6所述的薄膜体声波谐振器，还包括间隔层，该间隔层包括第一间隔膜和第二间隔膜；
    所述第一间隔膜位于所述第一压电膜和所述上电极层之间，且底部与所述衬底接触；所述第二间隔膜位于所述第二压电膜和所述上电极层之间，且底部与所述第二下电极的第一部分接触；或
    所述第一间隔膜位于所述第一下电极和所述第一压电膜之间，且底部与所述衬底接触；所述第二间隔膜位于所述第二下电极与所述第二压电膜之间，且底部与所述第二下电极的第一部分接触。
  8. 根据权利要求5所述的薄膜体声波谐振器，还包括第一凸起和第二凸起；
    第一凸起位于所述上电极层与所述第一压电膜之间、且位于所述上电极层的第二部分的其中一端部；或第一凸起位于所述第一压电膜与第一下电极的第三部分之间、且位于所述第一压电膜的一端部；
    所述第二凸起位于所述上电极层与所述第二压电膜之间、且位于所述上电极层的第二部分的其中另一端部；或第二凸起位于所述第二压电膜与第二下电极的第三部分之间、且位于所述第二压电膜的一端部。
  9. 根据权利要求5所述的薄膜体声波谐振器，还包括焊盘层，位于所述上电极层及所述下电极层上。
  10. 根据权利要求9所述的薄膜体声波谐振器，其中，所述焊盘层部分覆盖所述上电极层的第二部分、所述第一下电极的第一部分、及所述第二下电极的第五部分或第一部分。
  11. 根据权利要求3所述的薄膜体声波谐振器，其中，所述导电层包括第一导电膜和第二导电膜；
    所述下电极层包括第一下电极和第二下电极；所述第一下电极包括相 连的第一部分和第二部分；第一下电极的第一部分沿着平行于衬底的方向延伸，第一下电极的第二部分沿着垂直于衬底的方向延伸，且与所述衬底接触，所述第一下电极的第一部分与所述第一导电膜之间具有一间隙；第二下电极沿平行于所述衬底的方向延伸，且与所述第二导电膜之间具有一间隙。
  12. 根据权利要求11所述的薄膜体声波谐振器，其中，所述压电层包括第一压电膜和第二压电膜，所述第一压电膜完全覆盖第一下电极的第一部分和第二部分；所述第二压电膜完全覆盖所述第二下电极。
  13. 根据权利要求12所述的薄膜体声波谐振器，其中，所述上电极层包括：第一部分，沿垂直于衬底的方向延伸，其底部同时与所述衬底及所述第二导电膜接触，且所述上电极层的第一部分位于所述第一压电膜与第二压电膜之间；以及第二部分，位于所述压电层上，沿平行于所述衬底的方向延伸。
  14. 根据权利要求13所述的薄膜体声波谐振器，其中，所述薄膜体声波谐振器还包括间隔层，该间隔层包括第一间隔膜和第二间隔膜；所述第一间隔膜位于所述第一压电膜和所述上电极层之间，且底部与所述衬底接触；所述第二间隔膜位于所述第二压电膜和所述上电极层之间，且底部与所述第二导电膜接触。
  15. 根据权利要求4所述的薄膜体声波谐振器，其中，
    所述压电层包括第一压电膜和第二压电膜，第一压电膜形成于所述第一下电极的第三部分上，第二压电膜形成于所述第二下电极的第三部分上。
  16. 根据权利要求15所述的薄膜体声波谐振器，其中，
    所述上电极层包括：第一部分，沿垂直于衬底的方向延伸，其底部同时与所述衬底及所述第二下电极的第一部分接触，且所述上电极层的第一部分位于所述第一压电膜与第二压电膜之间且位于所第一下电极的第四部分与所述第二下电极的第二部分之间；以及第二部分，位于所述压电层上，沿平行于所述衬底的方向延伸。
  17. 根据权利要求16所述的薄膜体声波谐振器，还包括间隔层，该间隔层包括第一间隔膜和第二间隔膜；所述第一间隔膜的底部与所述衬底接触，且完全覆盖所述第一下电极的第四部分、部分覆盖所述第一下电极的 第三部分及部分覆盖所述第一压电膜；所述第一间隔膜的底部与所述第二下电极的第一部分接触，且完全覆盖所述第二下电极的第二部分、部分覆盖所述第二下电极的第三部分及部分覆盖所述第二压电膜。
  18. 根据权利要求7所述的薄膜体声波谐振器，其中，
    所述中柱结构包括：所述上电极层的与所述衬底垂直的部分，所述间隔层的与所述衬底垂直的部分，所述压电层的与所述衬底垂直的部分，所述下电极层的与所述衬底垂直、且靠近所述间隔层的部分。
  19. 一种薄膜体声波谐振器的制作方法，包括：
    在衬底上生长牺牲层并图形化处理，形成第一开口区域；
    生长下电极层并刻蚀下电极层，在所述第一开口区域内形成第二开口区域；
    生长压电层和上电极层；
    刻蚀上电极层，并刻蚀压电层，在所述第二开口区域内形成第三开口区域；
    刻蚀去除所述牺牲层，在所述下电极与所述衬底之间、所述薄膜体声波谐振器的有效谐振区域形成空腔。
  20. 根据权利要求19所述的薄膜体声波谐振器的制作方法，还包括：在所述下电极层与所述压电层之间或所述压电层与所述压电层与所述上电极层之间生长隔离层，并作图像化处理。
  21. 根据权利要求19所述的薄膜体声波谐振器的制作方法，其中，在生长牺牲层之前，还包括：生长导电层并作图像化处理。
  22. 根据权利要求20所述的薄膜体声波谐振器的制作方法，其中，还包括：在所述下电极层与所述压电层或所述压电层与所述上电极之间形成凸起结构。
  23. 一种滤波器，其包括级联的多个如权利要求1-18中任一项所述薄膜体声波谐振器。
PCT/CN2018/121770 2018-12-18 2018-12-18 薄膜体声波谐振器及其制作方法、滤波器 WO2020124369A1 (zh)

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US20130049888A1 (en) * 2011-08-24 2013-02-28 Avago Technologies Wireless Ip (Singapore) Pte. Ltd. Acoustic resonator formed on a pedestal
CN103296992A (zh) * 2013-06-28 2013-09-11 中国电子科技集团公司第二十六研究所 薄膜体声波谐振器结构及其制造方法
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CN107231138A (zh) * 2016-12-29 2017-10-03 杭州左蓝微电子技术有限公司 带有支撑结构的薄膜体声波谐振器及其制备方法

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US20130049888A1 (en) * 2011-08-24 2013-02-28 Avago Technologies Wireless Ip (Singapore) Pte. Ltd. Acoustic resonator formed on a pedestal
CN103296992A (zh) * 2013-06-28 2013-09-11 中国电子科技集团公司第二十六研究所 薄膜体声波谐振器结构及其制造方法
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