WO2020132996A1 - 一种单晶压电薄膜体声波谐振器以及制作方法 - Google Patents

一种单晶压电薄膜体声波谐振器以及制作方法 Download PDF

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WO2020132996A1
WO2020132996A1 PCT/CN2018/124077 CN2018124077W WO2020132996A1 WO 2020132996 A1 WO2020132996 A1 WO 2020132996A1 CN 2018124077 W CN2018124077 W CN 2018124077W WO 2020132996 A1 WO2020132996 A1 WO 2020132996A1
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single crystal
top electrode
piezoelectric
bottom electrode
forming
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French (fr)
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庞慰
孙崇玲
杨清瑞
张孟伦
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Tianjin University
ROFS Microsystem Tianjin Co Ltd
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Tianjin University
ROFS Microsystem Tianjin Co Ltd
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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 elements; 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
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N30/00—Piezoelectric or electrostrictive devices
    • H10N30/01—Manufacture or treatment
    • H10N30/09—Forming piezoelectric or electrostrictive materials
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N30/00—Piezoelectric or electrostrictive devices
    • H10N30/20—Piezoelectric or electrostrictive devices with electrical input and mechanical output, e.g. functioning as actuators or vibrators

Definitions

  • the invention relates to the technical field of semiconductors, in particular to a single crystal piezoelectric film bulk acoustic wave resonator and a manufacturing method.
  • the thin film piezoelectric bulk acoustic resonator is characterized by a sandwich structure of the main body of the resonator. As shown in FIG. 1, the top electrode TE, the piezoelectric layer PZ, and the bottom electrode BE are used in order from top to bottom. The reverse piezoelectric effect has a resonance at a certain frequency to the external electrical excitation.
  • the piezoelectric thin film materials used in thin film bulk acoustic resonators are polycrystalline nitride thin films prepared by magnetron sputtering technology.
  • the thin film quality is poor and the defect density is high, which cannot meet the lower insertion loss and more of the future mobile communication technology.
  • High bandwidth and other requirements; the emergence of single crystal piezoelectric thin film materials make up for this problem.
  • the single crystal piezoelectric thin film bulk acoustic resonator not only has a higher frequency, but also has some properties better than the traditional piezoelectric thin film bulk acoustic resonator, which has received great attention from academic and industrial circles in recent years.
  • the preparation process of single crystal materials is difficult, and it is difficult to adopt the traditional process to prepare single crystal piezoelectric thin film bulk acoustic resonators with better performance.
  • the electrodes of the bulk acoustic wave resonator are fabricated on the prepared single crystal piezoelectric film. Therefore, the signal terminal and the reference ground electrode can only be On the same surface of the piezoelectric film, this electrode structure occupies a large area, and because the electric field distribution is not completely perpendicular to the piezoelectric film, the effective electromechanical coupling coefficient of the resonator is small. In addition, in the filter application, the resonator of this structure is not easy to achieve diversified interconnection between electrodes. (2) As shown in FIG.
  • the single crystal material is directly grown on the bottom electrode under high temperature conditions, which is difficult and difficult to achieve; in addition, the crystal orientation of the single crystal material in some areas due to the presence of the bottom electrode slope Changes, the single crystal thin film is poor in uniformity.
  • the bottom electrode is deposited from the back; this process has a high complexity, resulting in a low device yield and is not suitable Mass production.
  • the present invention provides a single crystal piezoelectric film bulk acoustic wave resonator and a manufacturing method to overcome the defects of the prior art.
  • the invention provides a method for manufacturing a single crystal piezoelectric thin film bulk acoustic resonator, which includes: forming a piezoelectric structure and a top electrode on a donor substrate, wherein the top electrode is on the piezoelectric structure; A cavity and a bottom electrode are formed on the substrate, wherein the bottom electrode covers the cavity; a dry transfer printing process is used to transfer the piezoelectric structure and the top electrode from the donor substrate to the bottom electrode Above.
  • the step of forming the piezoelectric structure and the top electrode on the donor substrate includes: providing a donor substrate; forming an adhesion layer on the donor substrate; and forming a single crystal on the adhesion layer A piezoelectric thin film layer; forming a top electrode layer on the single crystal piezoelectric thin film layer; patterning the single crystal piezoelectric thin film layer and the top electrode layer to obtain the piezoelectric structure and the top electrode.
  • the step of forming a cavity and a bottom electrode on the transfer substrate includes: forming the cavity on the top surface of the transfer substrate; filling the cavity with a sacrificial material; and on the transfer substrate A bottom electrode layer is formed thereon, wherein the bottom electrode layer covers the sacrificial material; the bottom electrode layer is patterned to obtain the bottom electrode; and the sacrificial material is removed to restore the cavity.
  • the step of transferring the piezoelectric structure and the top electrode from the donor substrate to the bottom electrode using a dry transfer printing process includes: etching the adhesion layer to form Anchor structure; use a soft seal to stick the piezoelectric structure and the top electrode, disconnect the anchor structure to separate the piezoelectric structure and the top electrode from the donor substrate; use a soft seal to separate the The piezoelectric structure and the top electrode are imprinted on the bottom electrode.
  • the material of the piezoelectric structure is: single crystal aluminum nitride, single crystal lithium niobate, single crystal lead zirconate titanate, single crystal potassium niobate, or single crystal lithium tantalate.
  • the material of the top electrode is the following metals or their alloys: gold, tungsten, molybdenum, platinum, ruthenium, iridium, germanium, copper, titanium, titanium tungsten, aluminum, chromium, arsenic doped gold.
  • the material of the bottom electrode is the following metals or their alloys: gold, tungsten, molybdenum, platinum, ruthenium, iridium, germanium, copper, titanium, titanium tungsten, aluminum, chromium, arsenic doped gold.
  • the material of the donor substrate is silicon or lithium niobate
  • the material of the adhesion layer is silicon dioxide
  • the material of the transfer substrate is silicon, glass, ceramic, diamond, silicon carbide, polyimide, parylene, polycarbonate, polyester resin, polyethylene naphthalate, polyether Sulfone, polyetherimide, polydimethylsiloxane, polyvinyl alcohol or fluoropolymer.
  • the material of the soft seal is dimethyl siloxane.
  • the invention also proposes a single crystal piezoelectric film bulk acoustic wave resonator, which is manufactured by the manufacturing method of the single crystal piezoelectric film bulk acoustic wave resonator of the invention.
  • the technical solution of the present invention transfers the single crystal piezoelectric film with a top electrode to a patterned bottom electrode through a thin film transfer process.
  • the operation is simple and can be manufactured on a large scale, thereby overcoming the shortcomings of the traditional process, and at the same time
  • the resonator structure in which the upper and lower electrodes are distributed on both sides of the single crystal film is realized, which can greatly improve the resonator performance.
  • Figure 1 is a schematic diagram of the principle of a thin film piezoelectric bulk acoustic resonator
  • FIGS. 2A to 2C are schematic diagrams of processing a thin film piezoelectric bulk acoustic resonator in the prior art
  • FIG. 3 is a flowchart of a method for manufacturing a single crystal piezoelectric thin film bulk acoustic resonator according to an embodiment of the invention
  • 4 to 12 are schematic process diagrams of a method for manufacturing a single crystal piezoelectric thin film bulk acoustic resonator according to an embodiment of the present invention
  • 13A and 13B are a circuit diagram and a cross-sectional view of a two-stage half-ladder filter according to an embodiment of the present invention.
  • first and second are used for description purposes only, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of indicated technical features.
  • the features defined as “first” and “second” may explicitly or implicitly include one or more of the features.
  • the meaning of “plurality” is two or more, unless otherwise specifically limited.
  • the terms “installation”, “connected”, “connected”, “fixed” and other terms should be understood in a broad sense, for example, it can be a fixed connection or a detachable connection , Or integrally connected; it can be a mechanical connection or an electrical connection; it can be directly connected, or it can be indirectly connected through an intermediary, or it can be the connection between two components.
  • installation can be a fixed connection or a detachable connection , Or integrally connected; it can be a mechanical connection or an electrical connection; it can be directly connected, or it can be indirectly connected through an intermediary, or it can be the connection between two components.
  • the first feature “above” or “below” the second feature may include the first and second features in direct contact, or may include the first and second features Not direct contact but contact through another feature between them.
  • the first feature is “above”, “above” and “above” the second feature includes that the first feature is directly above and obliquely above the second feature, or simply means that the first feature is higher in level than the second feature.
  • the first feature is “below”, “below”, and “below” the second feature includes that the first feature is directly below and obliquely below the second feature, or simply means that the first feature is less horizontal than the second feature.
  • the method for manufacturing a single crystal piezoelectric thin film bulk acoustic resonator according to an embodiment of the present invention, as shown in FIG. 3, includes the following steps:
  • a piezoelectric structure and a top electrode are formed on the donor substrate, where the top electrode is above the piezoelectric structure;
  • a dry transfer printing process is used to transfer the piezoelectric structure and top electrode from the donor substrate to the bottom electrode.
  • a high-quality single crystal piezoelectric structure is first grown on the donor substrate and then the single crystal piezoelectric structure is transferred to the transfer substrate
  • the two-step method of "on" because it does not require high temperature conditions and no back engraving process, has the characteristics of simplicity, low cost and high volume rate.
  • the performance of the single crystal piezoelectric film bulk acoustic wave resonator finally obtained is guaranteed to be good.
  • step A may include: providing a donor substrate; forming an adhesion layer on the donor substrate; forming a single crystal piezoelectric thin film layer on the adhesion layer; forming on the single crystal piezoelectric thin film layer Top electrode layer; the single crystal piezoelectric thin film layer and the top electrode layer are patterned to obtain a piezoelectric structure and a top electrode.
  • step B may include: forming a cavity on the top surface of the transfer substrate; filling the cavity with a sacrificial material; forming a bottom electrode layer on the transfer substrate, wherein the bottom electrode layer covers the sacrificial material; and placing the bottom electrode layer Graphic to get the bottom electrode; remove the sacrificial material to restore the cavity.
  • step C may include: etching the adhesion layer to form an anchor structure; using a soft seal to stick the piezoelectric structure and the top electrode, and disconnecting the anchor structure to separate the piezoelectric structure and the top electrode from the donor substrate; Use a soft stamp to stamp the piezoelectric structure and top electrode on top of the bottom electrode.
  • the material of the piezoelectric structure may be: single crystal aluminum nitride, single crystal lithium niobate, single crystal lead zirconate titanate, single crystal potassium niobate, or single crystal lithium tantalate.
  • the above-mentioned materials are piezoelectric thin films with a thickness of less than 10 microns.
  • the growth method of single crystal aluminum nitride is organometallic chemical vapor deposition (MOCVD).
  • the material of the top electrode may be the following metals or their alloys: gold, tungsten, molybdenum, platinum, ruthenium, iridium, germanium, copper, titanium, titanium tungsten, aluminum, chromium, arsenic doped gold.
  • the material of the top electrode is the following metals or their alloys: gold, tungsten, molybdenum, platinum, ruthenium, iridium, germanium, copper, titanium, titanium tungsten, aluminum, chromium, arsenic doped gold.
  • the materials of the top electrode and the bottom electrode are generally the same, but can also be different.
  • the material of the donor substrate may be silicon or lithium niobate, and the material of the adhesion layer may be silicon dioxide.
  • the material of the transfer substrate can be hard substrates such as silicon, glass, ceramics, diamond, silicon carbide, etc.; it can also be polyimide (PI), parylene (Parylene), polycarbonate (PC), Polyester resin (PET), polyethylene naphthalate (PEN), polyethersulfone (PES), polyetherimide (PEI), polydimethylsiloxane (PDMS), polyvinyl alcohol (PVA) ), and flexible substrates such as various fluoropolymers (FEP).
  • PI polyimide
  • Parylene parylene
  • PC polycarbonate
  • PET polyethylene naphthalate
  • PES polyethersulfone
  • PEI polyetherimide
  • PDMS polydimethylsiloxane
  • PVA polyvinyl alcohol
  • flexible substrates such as various fluoropolymers (FEP).
  • the material of the soft seal may be dimethyl siloxane.
  • the single crystal piezoelectric thin film bulk acoustic resonator according to the embodiment of the present invention is manufactured by the method disclosed in the present invention.
  • the technical solution of the present invention transfers the single crystal piezoelectric film with a top electrode to a patterned bottom electrode through a thin film transfer process.
  • the operation is simple and can be manufactured on a large scale, thereby overcoming the shortcomings of the traditional process, and at the same time
  • the resonator structure in which the upper and lower electrodes are distributed on both sides of the single crystal film is realized, which can greatly improve the resonator performance.
  • a silicon wafer with a mature preparation process on the market and a single crystal material of good quality is used as the donor substrate 11.
  • An adhesion layer 12 of silica material is grown on the donor substrate 11.
  • a high-quality lithium niobate (LiNbO 3 , LN) single crystal piezoelectric thin film layer 13 is prepared on the adhesion layer. As shown in Figure 4.
  • the top electrode 14 is prepared by magnetron sputtering technology, and then the top electrode layer 14 is patterned using photolithography, etching and other processes to obtain the top electrode 14, the shape of the top electrode 14 can be any shape, such as polygon, circle Shape, arc, etc. As shown in Figure 5.
  • the single crystal piezoelectric thin film layer 13 is patterned by processes such as photolithography and etching, and the piezoelectric structure 13 is obtained. As shown in Figure 6.
  • the bottom electrode 22 and the cavity 20 are prepared by processes such as deposition, photolithography, and etching, as shown in FIG. 7.
  • the cavity 20 may be prepared at this step, or it may be filled with sacrificial material first, and then etched to form a cavity when all devices are completed.
  • the core of this transfer method is to prepare an elastic soft seal 30 that can be elastically deformed, and its structural cross section is shown in FIG. 8.
  • the soft stamp 30 is composed of a base and an elastomer material that contacts the device.
  • the elastomer material may be dimethyl siloxane (PDMS), but it is not limited to the above materials.
  • the soft stamp 30 shown in FIG. 8 is used to transfer the top electrode 14 shown in FIG. 6 together with the piezoelectric structure 13 to the bottom electrode 22 shown in FIG. 7.
  • the adhesion layer 12 is etched to make the connection area between the adhesion layer 12 and the piezoelectric structure 13 as small as possible, as shown in FIG. 9. Specifically, most of the silica in the adhesion layer can be etched away, leaving only a small anchor structure connected to the piezoelectric structure 13. Then, the top electrode 14 and the piezoelectric structure 13 on the donor substrate 11 are adhered and pulled up using the soft seal 30, as shown in FIGS. 10A and 10B.
  • the soft stamp 30 with the top electrode 14 and the piezoelectric structure 13 is embossed on the bottom electrode 22, as shown in FIG.
  • a thin film bulk acoustic resonator whose piezoelectric layer is a single crystal material is obtained, as shown in FIG. 12.
  • a single crystal frequency filter device can be constructed by connecting the above-mentioned thin film bulk acoustic resonators according to a certain topology structure, and the most common resonator link topology structure of the filter is the ladder structure. Considering the electrical performance and mechanical performance, it is recommended to use two-stage half The ladder structure is shown in Figure 13A; the cross-sectional view is shown in Figure 13B.

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Abstract

一种单晶压电薄膜体声波谐振器以及制作方法，该制作方法包括：在供体基底之上形成压电结构和顶电极，其中顶电极在压电结构之上；在转移基底之上形成空腔和底电极，其中底电极覆盖空腔；采用干法转移印刷工艺将压电结构和顶电极从供体基底转移到底电极之上。该方法具有工艺简单易行、单晶压电薄膜质量好，生产良率高等优点。该单晶压电薄膜体声波谐振器性能良好。

Description

一种单晶压电薄膜体声波谐振器以及制作方法 技术领域
本发明涉及半导体技术领域，特别地涉及一种单晶压电薄膜体声波谐振器以及制作方法。
背景技术
近年来随着无线移动通讯技术的快速发展，体声波器件应用领域越来越广泛。与传统的体声波谐振器相比，具有体积小、质量轻、插入损耗低、频带宽以及品质因子高等优点的薄膜体声波谐振器逐渐占领市场。薄膜压电体声波谐振器，其特征是谐振器主体部分具有三明治结构，如图1所示，从上至下依次为顶电极TE、压电层PZ和底电极BE，利用压电薄膜材料所具有的逆压电效应，对外界电激励产生一定频率下的谐振。
目前薄膜体声波谐振器使用的压电薄膜材料大多采用磁控溅射技术制备的多晶氮化物薄膜，薄膜质量较差，缺陷密度较高，无法满足未来移动通讯技术更低的插入损耗、更高的带宽等要求；单晶压电薄膜材料的出现弥补了这一问题。单晶压电薄膜体声波谐振器不仅具有较高的频率，且部分性能优于传统压电薄膜材料的薄膜体声波谐振器，近年来得到学术界和产业界的高度关注。但单晶材料的制备工艺比较困难，很难采取传统的工艺流程制备性能较好的单晶压电薄膜体声波谐振器。
目前主要三种方式，但都有缺点：(1)如图2A所示，在已经制备好的单晶压电薄膜上加工制造体声波谐振器的电极，因此，信号端和参考地电极只能在压电薄膜的同一表面，这种电极结构所占面积较大，且由于电场分布不是完全垂直于压电薄膜，谐振器的有效机电耦 合系数较小。此外，在滤波器应用中，这种结构的谐振器不易于实现电极间的多样化互联。(2)如图2B所示，按照现有工艺制作，采取高温条件在底电极上直接生长单晶材料，工艺困难，难以实现；另外由于底电极斜坡的存在导致部分区域单晶材料的晶向改变，单晶薄膜均一性差。(3)如图2C所示，对已长有单晶材料的硅衬底进行背刻后，再从背面沉积底电极；这种方式的工艺复杂度高，导致器件良率较低，不适合大规模生产。
发明内容
有鉴于此，本发明提供一种单晶压电薄膜体声波谐振器以及制作方法，以克服现有技术的缺陷。
本发明提出一种单晶压电薄膜体声波谐振器的制作方法，包括：在供体基底之上形成压电结构和顶电极，其中所述顶电极在所述压电结构之上；在转移基底之上形成空腔和底电极，其中所述底电极覆盖所述空腔；采用干法转移印刷工艺将所述压电结构和所述顶电极从所述供体基底转移到所述底电极之上。
可选地，所述在供体基底之上形成压电结构和顶电极的步骤包括：提供供体基底；在供体基底之上形成粘附层；在所述粘附层之上形成单晶压电薄膜层；在所述单晶压电薄膜层之上形成顶电极层；将所述单晶压电薄膜层和所述顶电极层图形化，以得到所述压电结构和所述顶电极。
可选地，所述在转移基底之上形成空腔和底电极的步骤包括：在所述转移基底的顶表面形成所述空腔；在所述空腔中填充牺牲材料；在所述转移基底之上形成底电极层，其中所述底电极层覆盖所述牺牲材料；将所述底电极层图形化以得到所述底电极；去除所述牺牲材料以恢复所述空腔。
可选地，所述采用干法转移印刷工艺将所述压电结构和所述顶电极从所述供体基底转移到所述底电极之上的步骤包括：刻蚀所述粘附层以形成锚结构；利用软印章粘住所述压电结构和所述顶电极，断开所述锚结构以使所述压电结构和所述顶电极与所述供体基底分离；利用软印章将所述压电结构和所述顶电极压印在所述底电极之上。
可选地，所述压电结构的材料为：单晶氮化铝、单晶铌酸锂、单晶锆钛酸铅、单晶铌酸钾、或者单晶钽酸锂。
可选地，所述顶电极的材料为如下金属或者它们的合金：金、钨、钼、铂、钌、铱、锗、铜、钛、钛钨、铝、铬、砷掺杂金。
可选地，所述底电极的材料为如下金属或者它们的合金：金、钨、钼、铂、钌、铱、锗、铜、钛、钛钨、铝、铬、砷掺杂金。
可选地，所述供体基底的材料为硅或者铌酸锂，所述粘附层的材料为二氧化硅。
可选地，所述转移基底的材料为硅、玻璃、陶瓷、金刚石、碳化硅、聚酰亚胺、聚对二甲苯、聚碳酸酯、涤纶树脂、聚萘二甲酸乙二醇酯、聚醚砜、聚醚酰亚胺、聚二甲基硅氧烷、聚乙烯醇或者含氟聚合物。
可选地，所述软印章的材料为二甲基硅氧烷。
本发明还提出一种单晶压电薄膜体声波谐振器，该单晶压电薄膜体声波谐振器是通过本发明的单晶压电薄膜体声波谐振器的制作方法制作的。
由上可知，本发明的技术方案通过薄膜转移工艺，将带有顶电极的单晶压电薄膜转移到图形化的底电极上，操作简单，能够大规模制造，从而克服传统工艺的缺点，同时实现了上下电极分布在单晶薄膜两侧的谐振器结构，能够极大的提高谐振器性能。
附图说明
附图用于更好地理解本发明，不构成对本发明的不当限定。其中：
图1为薄膜压电体声波谐振器的原理示意图；
图2A至图2C为现有技术加工薄膜压电体声波谐振器的示意图；
图3为本发明实施例的单晶压电薄膜体声波谐振器的制作方法的流程图；
图4至图12为本发明实施例的单晶压电薄膜体声波谐振器的制作方法的过程示意图；
图13A和图13B为本发明实施例的两级半Ladder结构的滤波器的电路图和截面图。
具体实施方式
下面详细描述本发明的实施例，所述实施例的示例在附图中示出，其中自始至终相同或类似的标号表示相同或类似的元件或具有相同或类似功能的元件。下面通过参考附图描述的实施例是示例性的，旨在用于解释本发明，而不能理解为对本发明的限制。
在本发明的描述中，需要理解的是，术语“中心”、“纵向”、“横向”、“长度”、“宽度”、“厚度”、“上”、“下”、“前”、“后”、“左”、“右”、“竖直”、“水平”、“顶”、“底”“内”、“外”、“顺时针”、“逆时针”等指示的方位或位置关系为基于附图所示的方位或位置关系，仅是为了便于描述本发明和简化描述，而不是指示或暗示所指的装置或元件必须具有特定的方位、以特定的方位构造和操作，因此不能理解为对本发明的限制。
此外，术语“第一”、“第二”仅用于描述目的，而不能理解为指示或暗示相对重要性或者隐含指明所指示的技术特征的数量。由此，限定有“第一”、“第二”的特征可以明示或者隐含地包括一个或者更多个该特征。在本发明的描述中，“多个”的含义是两个或两个以上，除非另有明确具体的限定。
在本发明中，除非另有明确的规定和限定，术语“安装”、“相连”、“连接”、“固定”等术语应做广义理解，例如，可以是固定连接，也可以是可拆卸连接，或一体地连接；可以是机械连接，也可以是电连接；可以是直接相连，也可以通过中间媒介间接相连，可以是两个元件内部的连通。对于本领域的普通技术人员而言，可以根据具体情况理解上述术语在本发明中的具体含义。
在本发明中，除非另有明确的规定和限定，第一特征在第二特征之“上”或之“下”可以包括第一和第二特征直接接触，也可以包括第一和第二特征不是直接接触而是通过它们之间的另外的特征接触。而且，第一特征在第二特征“之上”、“上方”和“上面”包括第一特征在第二特征正上方和斜上方，或仅仅表示第一特征水平高度高于第二特征。第一特征在第二特征“之下”、“下方”和“下面”包括第一特征在第二特征正下方和斜下方，或仅仅表示第一特征水平高度小于第二特征。
根据本发明实施例的单晶压电薄膜体声波谐振器的制作方法，如图3所示，包括如下步骤：
A：在供体基底之上形成压电结构和顶电极，其中顶电极在压电结构之上；
B：在转移基底之上形成空腔和底电极，其中底电极覆盖空腔；
C：采用干法转移印刷工艺将压电结构和顶电极从供体基底转移到底电极之上。
根据本发明实施例的单晶压电薄膜体声波谐振器的制作方法，采用了“先在供体基底上生长出高质量的单晶压电结构然后将单晶压电结构转移到转移基底之上”的两步法，由于无需高温条件、无需背刻工艺，具有简单易行，成本低，量率高的特点。同时由于单晶压电结构质量好，缺陷少，保证了最终加工得到的单晶压电薄膜体声波谐振器的性能良好。
其中，步骤A可以具体过程可以包括：提供供体基底；在供体基底之上形成粘附层；在粘附层之上形成单晶压电薄膜层；在单晶压电薄膜层之上形成顶电极层；将单晶压电薄膜层和顶电极层图形化，得到压电结构和顶电极。
其中，步骤B的具体过程可以包括：在转移基底的顶表面形成空腔；在空腔中填充牺牲材料；在转移基底之上形成底电极层，其中底电极层覆盖牺牲材料；将底电极层图形化以得到底电极；去除牺牲材料以恢复空腔。
其中，步骤C的具体过程可以包括：刻蚀粘附层以形成锚结构；利用软印章粘住压电结构和顶电极，断开锚结构以使压电结构和顶电极与供体基底分离；利用软印章将压电结构和顶电极压印在底电极之上。
其中，压电结构的材料可以为：单晶氮化铝、单晶铌酸锂、单晶锆钛酸铅、单晶铌酸钾、或者单晶钽酸锂等。上述材料为压电薄膜，厚度小于10微米。单晶氮化铝生长方式为有机金属化学气相沉积法(MOCVD)等。
其中，顶电极的材料可以为如下金属或者它们的合金：金、钨、钼、铂、钌、铱、锗、铜、钛、钛钨、铝、铬、砷掺杂金。同样地， 顶电极的材料为如下金属或者它们的合金：金、钨、钼、铂、钌、铱、锗、铜、钛、钛钨、铝、铬、砷掺杂金。顶电极和底电极材料一般相同，但也可以不同。
其中，供体基底的材料可以为硅或者铌酸锂，粘附层的材料可以为二氧化硅。
其中，转移基底的材料可以为硅、玻璃、陶瓷、金刚石、碳化硅、等硬质基底；也可以为聚酰亚胺(PI)、聚对二甲苯(Parylene)、聚碳酸酯(PC)、涤纶树脂(PET)、聚萘二甲酸乙二醇酯(PEN)、聚醚砜(PES)、聚醚酰亚胺(PEI)、聚二甲基硅氧烷(PDMS)、聚乙烯醇(PVA)、和各种含氟聚合物(FEP)等柔性基底。
其中，软印章的材料可以为二甲基硅氧烷。
根据本发明实施例的单晶压电薄膜体声波谐振器，其是通过本发明公开的方法制作的。
由上可知，本发明的技术方案通过薄膜转移工艺，将带有顶电极的单晶压电薄膜转移到图形化的底电极上，操作简单，能够大规模制造，从而克服传统工艺的缺点，同时实现了上下电极分布在单晶薄膜两侧的谐振器结构，能够极大的提高谐振器性能。
为使本领域技术人员更好地理解，下面结合具体实施例进行说明详本发明的单晶压电薄膜体声波谐振器的制作过程。
(1)采用目前市面上制备工艺较成熟、单晶材料质量较好的硅晶圆作为供体基底11。在供体基底11之上生长二氧化硅材料的粘附层12。然后再在粘附层上制备高质量的铌酸锂(LiNbO 3，LN)的单晶压电薄膜层13。如图4所示。
(2)采用磁控溅射技术制备顶电极14，然后采用光刻、刻蚀等工艺将顶电极层14图形化，得到了顶电极14，顶电极14形状可以为任意形状，如多边形、圆形、弧形等。如图5所示。
(3)采用光刻、刻蚀等工艺将单晶压电薄膜层13图形化，得到了压电结构13。如图6所示。
(4)在另一个硅晶圆的转移基底21上，通过沉积、光刻、刻蚀等工艺制备底电极22及空腔20，如图7所示。空腔20可在此步制备，也可先填充牺牲材料，待器件全部制作完成时再刻蚀形成空腔。
(5)采用干法转移印刷法转移器件。这种转移方法的核心是制备一种可产生弹性变形的弹性体软印章30，其结构截面如图8所示。软印章30由基座和与器件接触面弹性体材料构成，弹性体材料可以是二甲基硅氧烷(PDMS)，但并不局限于以上材料。
采用图8所示的软印章30将图6所示中的顶电极14与压电结构13一起转移至图7所示的底电极22上。转移前，先对粘附层12进行刻蚀，使粘附层12与压电结构13连接的面积尽量小，如图9所示。具体地，可以刻蚀掉绝大部分粘附层中的二氧化硅，只留下很小的锚结构与压电结构13连接。然后利用软印章30把在供体基底11上的顶电极14及压电结构13粘住并提拉起来，如图10A和图10B所示。然后将带有顶电极14及压电结构13的软印章30压印到底电极22上，如图11所示。最后，将软印章30去除后，获得压电层为单晶材料的薄膜体声波谐振器，如图12所示。
按照一定的拓扑结构连接上述薄膜体声波谐振器可以构建单晶频率滤波器件，其中最常见的组成滤波器的谐振器链接拓扑结构为Ladder结构，综合考虑电学性能和机械性能，建议采用两级半的Ladder结构如图13A所示；其截面图如图13B所示。
上述具体实施方式，并不构成对本发明保护范围的限制。本领域技术人员应该明白的是，取决于设计要求和其他因素，可以发生各种各样的修改、组合、子组合和替代。任何在本发明的精神和原则之内 所作的修改、等同替换和改进等，均应包含在本发明保护范围之内。

Claims (11)

  1. 一种单晶压电薄膜体声波谐振器的制作方法，其特征在于，包括：
    在供体基底之上形成压电结构和顶电极，其中所述顶电极在所述压电结构之上；
    在转移基底之上形成空腔和底电极，其中所述底电极覆盖所述空腔；
    采用干法转移印刷工艺将所述压电结构和所述顶电极从所述供体基底转移到所述底电极之上。
  2. 根据权利要求1所述的方法，其特征在于，所述在供体基底之上形成压电结构和顶电极的步骤包括：
    提供供体基底；
    在供体基底之上形成粘附层；
    在所述粘附层之上形成单晶压电薄膜层；
    在所述单晶压电薄膜层之上形成顶电极层；
    将所述单晶压电薄膜层和所述顶电极层图形化，以得到所述压电结构和所述顶电极。
  3. 根据权利要求1所述的方法，其特征在于，所述在转移基底之上形成空腔和底电极的步骤包括：
    在所述转移基底的顶表面形成所述空腔；
    在所述空腔中填充牺牲材料；
    在所述转移基底之上形成底电极层，其中所述底电极层覆盖所述牺牲材料；
    将所述底电极层图形化以得到所述底电极；
    去除所述牺牲材料以恢复所述空腔。
  4. 根据权利要求2所述的方法，其特征在于，所述采用干法转移 印刷工艺将所述压电结构和所述顶电极从所述供体基底转移到所述底电极之上的步骤包括：
    刻蚀所述粘附层以形成锚结构；
    利用软印章粘住所述压电结构和所述顶电极，断开所述锚结构以使所述压电结构和所述顶电极与所述供体基底分离；
    利用软印章将所述压电结构和所述顶电极压印在所述底电极之上。
  5. 根据权利要求1所述的方法，其特征在于，所述压电结构的材料为：单晶氮化铝、单晶铌酸锂、单晶锆钛酸铅、单晶铌酸钾、或者单晶钽酸锂。
  6. 根据权利要求1所述的方法，其特征在于，所述顶电极的材料为如下金属或者它们的合金：金、钨、钼、铂、钌、铱、锗、铜、钛、钛钨、铝、铬、砷掺杂金。
  7. 根据权利要求1所述的方法，其特征在于，所述底电极的材料为如下金属或者它们的合金：金、钨、钼、铂、钌、铱、锗、铜、钛、钛钨、铝、铬、砷掺杂金。
  8. 根据权利要求1所述的方法，其特征在于，所述供体基底的材料为硅或者铌酸锂，所述粘附层的材料为二氧化硅。
  9. 根据权利要求1所述的方法，其特征在于，所述转移基底的材料为硅、玻璃、陶瓷、金刚石、碳化硅、聚酰亚胺、聚对二甲苯、聚碳酸酯、涤纶树脂、聚萘二甲酸乙二醇酯、聚醚砜、聚醚酰亚胺、聚二甲基硅氧烷、聚乙烯醇或者含氟聚合物。
  10. 根据权利要求4所述的方法，其特征在于，所述软印章的材料为二甲基硅氧烷。
  11. 一种单晶压电薄膜体声波谐振器，其特征在于，该单晶压电薄膜体声波谐振器是通过权利要求1至10中任一项所述的方法制作的。
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