WO2024108706A1 - 一种体声波谐振器及其制备方法 - Google Patents

一种体声波谐振器及其制备方法 Download PDF

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WO2024108706A1
WO2024108706A1 PCT/CN2022/140679 CN2022140679W WO2024108706A1 WO 2024108706 A1 WO2024108706 A1 WO 2024108706A1 CN 2022140679 W CN2022140679 W CN 2022140679W WO 2024108706 A1 WO2024108706 A1 WO 2024108706A1
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layer
electrode layer
substrate
acoustic wave
cavity
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PCT/CN2022/140679
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English (en)
French (fr)
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李国强
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广州市艾佛光通科技有限公司
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    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
    • H03H3/00—Apparatus or processes specially adapted for the manufacture of impedance networks, resonating circuits, resonators
    • H03H3/007—Apparatus or processes specially adapted for the manufacture of impedance networks, resonating circuits, resonators for the manufacture of electromechanical resonators or networks
    • H03H3/02—Apparatus or processes specially adapted for the manufacture of impedance networks, resonating circuits, resonators for the manufacture of electromechanical resonators or networks for the manufacture of piezoelectric or electrostrictive resonators or networks
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
    • H03H3/00—Apparatus or processes specially adapted for the manufacture of impedance networks, resonating circuits, resonators
    • H03H3/007—Apparatus or processes specially adapted for the manufacture of impedance networks, resonating circuits, resonators for the manufacture of electromechanical resonators or networks
    • H03H3/02—Apparatus or processes specially adapted for the manufacture of impedance networks, resonating circuits, resonators for the manufacture of electromechanical resonators or networks for the manufacture of piezoelectric or electrostrictive resonators or networks
    • H03H3/04—Apparatus or processes specially adapted for the manufacture of impedance networks, resonating circuits, resonators for the manufacture of electromechanical resonators or networks for the manufacture of piezoelectric or electrostrictive resonators or networks for obtaining desired frequency or temperature coefficient
    • 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
    • H03H9/02—Details
    • H03H9/05—Holders; Supports
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
    • H03H9/00—Networks comprising electromechanical or electro-acoustic devices; Electromechanical resonators
    • H03H9/02—Details
    • H03H9/125—Driving means, e.g. electrodes, coils
    • H03H9/13—Driving means, e.g. electrodes, coils for networks consisting of piezoelectric or electrostrictive materials
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
    • 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

Definitions

  • the present invention relates to the technical field of semiconductor device manufacturing, and in particular to a bulk acoustic wave resonator and a preparation method thereof.
  • Film bulk acoustic wave resonators use piezoelectric materials to convert electrical signals into acoustic signals. Due to the low speed and short wavelength of acoustic waves, compared with other types of resonators, they have the advantages of small size and high operating frequency, and are widely used in RF front-end circuits. At present, film bulk acoustic wave filters have been widely used in 5G filters, but aluminum nitride-based film bulk acoustic wave filters still have various defects. Fixed or non-adjustable frequency severely limits the multi-frequency application of resonators, and there are still few reports on frequency-adjustable bulk acoustic wave resonators.
  • an embodiment of the present invention aims to solve at least one of the above technical problems in the prior art to a certain extent.
  • an embodiment of the present invention provides a BAW resonator, which optimizes the structure of the BAW resonator so that the frequency of the BAW resonator can be adjusted within a certain range.
  • the embodiment of the present invention also provides a method for preparing a bulk acoustic wave resonator.
  • a bulk acoustic wave resonator comprising a substrate, a surface of the substrate having a concave cavity; a first electrode layer, one side of the first electrode layer covering the concave cavity; a piezoelectric layer, the piezoelectric layer being bonded to the substrate and covering the remaining side of the first electrode layer; a second electrode layer, the second electrode layer being bonded to and connected to a side of the piezoelectric layer away from the substrate; and a sensitive layer, the sensitive layer being bonded to and connected to a side of the second electrode layer away from the piezoelectric layer.
  • the above-mentioned BAW resonator has at least the following beneficial effects: changing the stacking structure of the electrode layer, reducing the area and thickness of the electrode layer, reducing the leakage of sound waves, and the set sensitive layer can absorb a large amount of hydrogen. Therefore, by selectively introducing nitrogen and hydrogen, the frequency shift and recovery of the BAW resonator can be achieved.
  • the depth of the cavity is 2 ⁇ m to 30 ⁇ m
  • the cross-sectional shape of the cavity is one of a rectangle, a triangle, and a trapezoid.
  • an area of a surface of the first electrode layer that is in contact with the substrate is smaller than half an area of a surface of the substrate that is in contact with the first electrode layer.
  • the thickness of the sensitive layer is in the range of 10 nm to 300 nm.
  • the thickness of the sensitive layer is 200 nm.
  • the sensitive layer is made of palladium.
  • the piezoelectric layer is made of aluminum nitride, and the thickness of the piezoelectric layer is in the range of 100 nm to 5 ⁇ m.
  • the thickness of the piezoelectric layer is 1000 nm.
  • the first electrode layer and the second electrode layer have the same thickness and shape
  • the second electrode layer and the first electrode layer are both made of one of Pt, Mo, Ag, Al, and Au
  • the thickness of the second electrode layer ranges from 60nm to 700nm.
  • a method for preparing a bulk acoustic wave resonator which is used to prepare the bulk acoustic wave resonator, comprising the following steps:
  • the substrate is prepared by using crystal surface high-resistance silicon
  • a support layer for keeping the substrate surface flat is formed in the cavity, and the material of the support layer is phosphorus silicon glass;
  • a piezoelectric layer is formed on the substrate, wherein the thickness of the piezoelectric layer is greater than the first electrode layer, and the first electrode layer is embedded on a side of the piezoelectric layer contacting the substrate;
  • a second electrode layer and a sensitive layer are sequentially prepared on a side of the piezoelectric layer away from the substrate;
  • the method for preparing the BAW resonator has at least the following beneficial effects: the frequency of the BAW resonator prepared by the method is adjustable, and the characteristics of the generated sensitive layer are utilized to absorb a large amount of hydrogen. Therefore, the frequency shift and recovery of the BAW resonator can be achieved by selectively introducing nitrogen and hydrogen.
  • the method for preparing the BAW resonator is also compatible with the CMOS process, the preparation process is simple, and no other electronic components need to be integrated, which greatly saves production costs.
  • FIG1 is a schematic structural diagram of a prepared substrate in an embodiment of the present invention.
  • FIG2 is a schematic diagram of a structure in which both the electrode layer and the piezoelectric layer are prepared in an embodiment of the present invention
  • FIG3 is a schematic diagram of a structure in which an electrode layer, a piezoelectric layer and a sensitive layer are all prepared in an embodiment of the present invention
  • FIG. 4 is a schematic structural diagram of a bulk acoustic wave resonator without a supporting layer in an embodiment of the present invention.
  • orientations such as up, down, front, back, left, right, etc.
  • orientations or positional relationships indicated are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present invention.
  • “several” means one or more, “more” means more than two, “greater than”, “less than”, “exceed” etc. are understood to exclude the number itself, and “above”, “below”, “within” etc. are understood to include the number itself. If there is a description of "first” or “second”, it is only used for the purpose of distinguishing the technical features, and cannot be understood as indicating or implying the relative importance or implicitly indicating the number of the indicated technical features or implicitly indicating the order of the indicated technical features.
  • the thin film bulk acoustic wave resonator (FBAR) developed in recent years adopts an advanced resonance technology, which converts electrical energy into sound waves through the inverse piezoelectric effect of piezoelectric film to form resonance.
  • This resonance technology can be used to make advanced components such as thin film frequency shaping devices.
  • the thin film bulk acoustic wave resonator (FBAR) acoustic wave device has the characteristics of small size, low cost, high quality factor (Q), strong power bearing capacity, high frequency (up to 1-10GHz) and compatibility with IC technology.
  • the existing film bulk acoustic wave filters have been widely used in 5G filters, but the film bulk acoustic wave filters based on aluminum nitride still have various defects.
  • the fixed or unadjustable frequency seriously limits the multi-frequency application of the resonator, and there are still few reports on frequency-adjustable bulk acoustic wave resonators.
  • an embodiment of the present invention provides a bulk acoustic wave resonator, including a substrate 100 , a first electrode layer 200 , a piezoelectric layer 300 , a second electrode layer 400 , and a sensitive layer 500 .
  • the surface of the substrate 100 has a cavity 110, and the material of the substrate 100 is crystal surface high-resistance silicon.
  • the substrate 100 is first soaked in acetone and ultrasonically cleaned, and then cleaned with a mixed solution of sulfuric acid and hydrogen peroxide and then dried.
  • the formation of the cavity 110 is to etch the upper surface of the substrate 100 by inductively coupled plasma to form a cavity 110 of a certain shape.
  • the depth of the cavity 110 is 2um to 30um
  • the cross-sectional shape of the cavity 110 is one of a rectangle, a triangle, and a trapezoid.
  • the cross-sectional shape of the cavity 110 is preferably a rectangle, and specifically, the depth of the cavity 110 is preferably 2um.
  • the material of the substrate 100 can also be one of glass, silicon, silicon carbide, sapphire, ceramics, etc. or any combination thereof.
  • One side of the first electrode layer 200 covers the cavity 110.
  • a layer of phosphosilicate glass is deposited in the cavity 110 by plasma enhanced chemical vapor deposition to form a support layer 700.
  • the phosphosilicate glass fills the cavity 110 and is deposited on the surface of the flat substrate 100.
  • the support layer 700 is mechanically polished and chemically polished so that the side of the support layer 700 flat substrate 100 is smooth and flat, which is convenient for the subsequent preparation of other layer structures, and then the first electrode layer 200 is prepared by magnetron sputtering.
  • the material of the support layer 700 can also be one of silicon nitride, silicon, tantalum nitride, ceramics, etc. or any combination thereof.
  • the plasma enhanced chemical vapor deposition method is to ionize the gas containing the atoms of the film components with the help of microwaves or radio frequencies, and form plasma locally.
  • the plasma chemical activity is very strong and it is easy to react to deposit the desired film on the substrate.
  • this CVD is called plasma enhanced chemical vapor deposition (PECVD).
  • PECVD plasma enhanced chemical vapor deposition
  • Magnetron sputtering is a type of physical vapor deposition (PVD).
  • the general sputtering method can be used to prepare multiple materials such as metals, semiconductors, and insulators, and has the advantages of simple equipment, easy control, large coating area, and strong adhesion.
  • magnetron sputtering The magnetron sputtering method developed in the 1970s has achieved high speed, low temperature, and low damage. Because high-speed sputtering is carried out under low pressure, the ionization rate of the gas must be effectively increased. Magnetron sputtering introduces a magnetic field on the surface of the target cathode and uses the magnetic field to constrain the charged particles to increase the plasma density and increase the sputtering rate.
  • a piezoelectric layer 300 is prepared on the surface of the substrate 100 and the first electrode layer 200.
  • the piezoelectric layer 300 is bonded to the substrate 100.
  • the piezoelectric layer 300 covers the remaining surface of the first electrode layer 200 except the surface bonded to the substrate 100, so that the first electrode layer 200 is embedded in the surface of the piezoelectric layer 300 bonded to the substrate 100. It should be noted that the manufacturing method of the piezoelectric layer 300 also adopts the magnetron sputtering method.
  • the second electrode layer 400 is manufactured next.
  • the second electrode layer 400 is bonded to the side of the piezoelectric layer 300 away from the substrate 100.
  • the second electrode layer 400 faces the first electrode layer 200.
  • the first electrode layer 200 is also manufactured by magnetron sputtering.
  • the final sensitive layer 500 is made.
  • the sensitive layer 500 is attached to the side of the second electrode layer 400 away from the piezoelectric layer 300.
  • the sensitive layer 500 is also made by magnetron sputtering.
  • the sensitive layer 500 is made of palladium.
  • the palladium-made sensitive layer 500 can absorb a large amount of hydrogen, so it can greatly change the frequency of the resonator.
  • the thickness of the sensitive layer 500 ranges from 10nm to 300nm. In this embodiment, the thickness of the sensitive layer 500 is preferably 200nm.
  • the area of the first electrode layer 200 on the side bonded to the substrate 100 is less than half the area of the side bonded to the substrate 100 and the first electrode layer 200, and the area of the first electrode layer 200 covering the substrate 100 should not be too large.
  • the first electrode layer 200 and the second electrode layer 400 have the same thickness and shape, and the second electrode layer 400 and the first electrode layer 200 are both made of one of Pt, Mo, Ag, Al, and Au, and the thickness of the second electrode layer 400 is in the range of 60 nm to 700 nm, wherein the thickness of the second electrode layer 400 and the first electrode layer 200 are both preferably 100 nm.
  • the piezoelectric layer 300 is made of aluminum nitride, and the thickness of the piezoelectric layer 300 ranges from 100 nm to 5 ⁇ m. In this embodiment, the thickness of the piezoelectric layer 300 is preferably 1000 nm.
  • the support layer 700 is released by using a hydrofluoric acid solution, and the fabrication of the BAW resonator is completed.
  • the embodiment of the present invention deposits a sensitive layer 500 made of palladium on the second electrode layer 400.
  • Palladium can absorb a large amount of hydrogen. Therefore, by selectively introducing nitrogen and hydrogen, the frequency shift and recovery of the BAW resonator can be achieved, solving the problem that the existing BAW resonator cannot adjust the frequency.
  • the thickness of the second electrode layer 400 and the first electrode layer 200 is 100nm
  • the thickness of the sensitive layer 500 is 200nm
  • the thickness of the piezoelectric layer 300 is 1000nm
  • the depth of the cavity 110 is 2 ⁇ m
  • the BAW resonator frequency adjustment range is relatively wide, up to 1MHz.
  • an embodiment of the present invention further provides a method for preparing the above-mentioned bulk acoustic wave resonator, which specifically includes the following steps:
  • the substrate 100 is prepared by using crystal surface high-resistance silicon. After the substrate 100 is prepared, the substrate 100 is first soaked in acetone and ultrasonically cleaned, and then cleaned with a mixed solution of sulfuric acid and hydrogen peroxide and then dried;
  • a concave cavity 110 is manufactured on the surface of a substrate 100 , and the upper surface of the substrate 100 is etched by inductively coupled plasma to form a concave cavity 110 of a certain shape.
  • the depth of the concave cavity 110 is 2 um to 30 um
  • the cross-sectional shape of the concave cavity 110 is one of a rectangle, a triangle, and a trapezoid;
  • a support layer 700 is formed in the cavity 110 to hold the surface of the flat substrate 100.
  • the material of the support layer 700 is phosphosilicate glass. Specifically, a layer of phosphosilicate glass is deposited in the cavity 110 by plasma enhanced chemical vapor deposition to form the support layer 700. The phosphosilicate glass fills the cavity 110 and is deposited on the surface of the flat substrate 100. After the support layer 700 is formed, the support layer 700 is mechanically polished and chemically polished so that the side of the support layer 700 that is held on the flat substrate 100 is smooth and flat, which is convenient for the subsequent production of other layer structures.
  • a first electrode layer 200 covering the cavity 110 is formed on the substrate 100 and the support layer 700 by plasma enhanced chemical vapor deposition.
  • the thickness of the first electrode layer 200 is in the range of 60 nm to 700 nm.
  • the first electrode layer 200 is made of one of Pt, Mo, Ag, Al, and Au.
  • the thickness of the first electrode layer 200 is preferably 100 nm, and the area of the first electrode layer 200 on the side bonded to the substrate 100 is less than half of the area of the side bonded to the substrate 100 and the first electrode layer 200.
  • a piezoelectric layer 300 is formed on the substrate 100 by plasma enhanced chemical vapor deposition.
  • the thickness of the piezoelectric layer 300 is greater than that of the first electrode layer 200.
  • the first electrode layer 200 is embedded in a side of the piezoelectric layer 300 that contacts the substrate 100.
  • the piezoelectric layer 300 is made of aluminum nitride.
  • the thickness of the piezoelectric layer 300 is in the range of 100 nm to 5 ⁇ m. In this embodiment, the thickness of the piezoelectric layer 300 is preferably 1000 nm.
  • a second electrode layer 400 and a sensitive layer 500 are sequentially prepared on a side of the piezoelectric layer 300 away from the substrate 100.
  • the first electrode layer 200 and the second electrode layer 400 have the same thickness and shape.
  • the second electrode layer 400 is made of one of Pt, Mo, Ag, Al, and Au.
  • the thickness of the second electrode layer 400 is in the range of 60 nm to 700 nm.
  • the thickness of the second electrode layer 400 and the first electrode layer 200 is preferably 100 nm.
  • the support layer 700 is removed and released by using a hydrofluoric acid solution. Thus, the fabrication of the BAW resonator is completed.
  • the frequency of the BAW resonator made by the above method is adjustable, and the characteristics of the generated sensitive layer 500 are used to absorb a large amount of hydrogen. Therefore, the frequency shift and recovery of the BAW resonator can be achieved by selectively introducing nitrogen and hydrogen.
  • the above method for preparing the BAW resonator is also compatible with the CMOS process, the preparation process is simple, and there is no need to integrate other electronic components, which greatly saves production costs.

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  • Engineering & Computer Science (AREA)
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Abstract

本发明公开了一种体声波谐振器及其制备方法，涉及半导体器件制造技术领域，包括衬底，所述衬底的表面具有凹腔；第一电极层，所述第一电极层的一面覆盖于所述凹腔；压电层，所述压电层贴合所述衬底，所述压电层将所述第一电极层的其余面覆盖；第二电极层，所述第二电极层贴合连接所述压电层远离所述衬底的一面；以及敏感层，所述敏感层贴合连接所述第二电极层远离所述压电层的一面。本发明实施例提供一种体声波谐振器，优化体声波谐振器的结构，使得体声波谐振器的频率能够在一定范围内调节。

Description

一种体声波谐振器及其制备方法 技术领域
本发明涉及半导体器件制造技术领域，特别涉及一种体声波谐振器及其制备方法。
背景技术
薄膜体声波谐振器利用压电材料将电学信号转换成为声学信号，由于声波的速度较低，声波波长短，因此与其他种类的谐振器相比，具有体积小、工作频率高的优点，广泛应用于射频前端电路。目前薄膜体声波滤波器已经大规模应用于5G滤波器，但是基于氮化铝的薄膜体声波滤波器仍然存在着各种各样的缺陷。频率固定或者不可调严重限制了谐振器的多频率应用，目前关于频率可调体声波谐振器的报道仍然很少。
发明内容
本发明旨在至少在一定程度上解决现有技术中的上述技术问题之一。为此，本发明实施例提供一种体声波谐振器，优化体声波谐振器的结构，使得体声波谐振器的频率能够在一定范围内调节。
本发明实施例还提供一种体声波谐振器的制备方法。
根据本发明第一方面的实施例，提供一种体声波谐振器，包括衬底，所述衬底的表面具有凹腔；第一电极层，所述第一电极层的一面覆盖于所述凹腔；压电层，所述压电层贴合所述衬底，所述压电层将所述第一电极层的其余面覆盖；第二电极层，所述第二电极层贴合连接所述压电层远离所述衬底的一面；以及敏感层，所述敏感层贴合连接所述第二电极层远离所述压电层的一面。
上述体声波谐振器，至少具有以下有益效果：改变电极层的层叠结构，减小电极层的面积和厚度，降低声波的泄漏，设置的敏感层可以大量吸收氢气，因此，利用选择性的通入氮气和氢气，即可实现体声波谐振器的频率移动和恢复。
根据本发明第一方面所述的体声波谐振器，所述凹腔的深度为2μm～30μm，所述凹腔的截面形状为矩形、三角形、梯形中的其中一种。
根据本发明第一方面所述的体声波谐振器，所述第一电极层与所述衬底贴合的一面的面积小于所述衬底与所述第一电极层贴合的一面的面积的二分之一。
根据本发明第一方面所述的体声波谐振器，所述敏感层的厚度范围在10nm～300nm。
根据本发明第一方面所述的体声波谐振器，所述敏感层的厚度为200nm。
根据本发明第一方面所述的体声波谐振器，所述敏感层由钯制成。
根据本发明第一方面所述的体声波谐振器，所述压电层由氮化铝制成，所述压电层的厚度范围在l00nm～5μm。
根据本发明第一方面所述的体声波谐振器，所述压电层的厚度为1000nm。
根据本发明第一方面所述的体声波谐振器，所述第一电极层和所述第二电极层的厚度和形状均相同，所述第二电极层和所述第一电极层均由Pt、Mo、Ag、Al、Au中的其中一种制成，所述第二电极层的厚度范围在60nm～700nm。
根据本发明第二方面的实施例，提供一种体声波谐振器的制备方法，用于制备上述的体声波谐振器，包括如下步骤：
采用晶面高阻硅制备衬底；
在衬底的表面制造凹腔；
在凹腔内形成持平衬底表面的支撑层，支撑层的材质为磷硅玻璃；
在衬底和支撑层上形成覆盖于凹腔的第一电极层；
在衬底上形成压电层，压电层的厚度大于第一电极层，第一电极层嵌设于压电层接触衬底的一面；
在压电层远离衬底的一面依次制备第二电极层、敏感层；
去除支撑层。
上述体声波谐振器的制备方法，至少具有以下有益效果：上述方法制成的体声波谐振器的频率可调，利用生成的敏感层的特性来大量吸收氢气，因此，利用选择性的通入氮气和氢气，即可实现体声波谐振器的频率移动和恢复，另外上述制备体声波谐振器的方法也能够与CMOS工艺相兼容，制备工艺简单，无需集成其它的电子元件，极大的节省了生产成本。
附图说明
下面结合附图和实施例对本发明进一步地说明；
图1是本发明实施例中，制备好的衬底的结构示意图；
图2是本发明实施例中，电极层和压电层均制备好的结构示意图；
图3是本发明实施例中，电极层、压电层以及敏感层均制备好的结构示意图；
图4是本发明实施例中，去除支撑层的体声波谐振器的结构示意图。
具体实施方式
本部分将详细描述本发明的具体实施例，本发明之较佳实施例在附图中示出，附图的作用在于用图形补充说明书文字部分的描述，使人能够直观地、形象地理解本发明的每个技术特征和整体技术方案，但其不能理解为对本发明保护范围的限制。
在本发明的描述中，需要理解的是，涉及到方位描述，例如上、下、前、后、左、右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。
在本发明的描述中，若干的含义是一个或者多个，多个的含义是两个以上，大于、小于、超过等理解为不包括本数，以上、以下、以内等理解为包括本数。如果有描述到第一、第二只是用于区分技术特征为目的，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或者隐含指明所指示的技术特征的先后关系。
本发明的描述中，除非另有明确的限定，设置、安装、连接等词语应做广义理解，所属技术领域技术人员可以结合技术方案的具体内容合理确定上述词语在本发明中的具体含义。
随着薄膜与微纳制造技术的发展，电子器件正向微型化、高密集复用、高频率和低功耗的方向迅速发展。近年来发展起来的薄膜体声波谐振器(FBAR)采用一种先进的谐振技术，它是通过压电薄膜的逆压电效应将电能量转换成声波而形成谐振，这一谐振技术可以用来制作薄膜频率整形器件等先进元器件，薄膜体声波谐振器(FBAR)声波器件具有体积小，成本低，品质因数(Q)高、功率承受能力强、频率高(可达1-l0GHz)且与IC技术兼容等特点，适合于工作在1-10GHz的RF系统应用，有望在未来的无线通讯系统中取代传统的声表面波(SAW)器件和微波陶瓷器，因此在新一代无线通信系统和超微量生化检测领域具有广阔的应用前景。
目前，现有的薄膜体声波滤波器已经大规模应用于5G滤波器，但是基于氮化铝的薄膜体声波滤波器仍然存在着各种各样的缺陷。频率固定或者不可调严重限制了谐振器的多频率应用，目前关于频率可调体声波谐振器的报道仍然很少。
参照图4，本发明实施例提供一种体声波谐振器，包括衬底100、第一电极层200、压电层300、第二电极层400以及敏感层500。
其中，衬底100的表面具有凹腔110，衬底100的材质为晶面高阻硅，衬底100制作好后，将衬底100先用丙酮浸泡并进行超声清洗，然后经过硫酸和过氧化氢混合溶液清洗完毕后进行干燥处理，而凹腔110的形成则通过电感耦合等离子体在衬底100的上表面刻蚀以形 成一定形状的凹腔110，本实施例中，凹腔110的深度为2um～30um，凹腔110的截面形状为矩形、三角形、梯形中的其中一种，如图1至图4所示，凹腔110的截面形状优选为矩形，具体的，凹腔110的深度优选为2um。在其它的一些实施例中，衬底100的材质也可以为玻璃，硅，碳化硅，蓝宝石，陶瓷等中的一种或其任意组合。
第一电极层200的一面覆盖于凹腔110上，在进行第一电极层200的制备时，利用等离子体增强化学的气相沉积法在凹腔110内沉积一层磷硅玻璃以形成支撑层700，磷硅玻璃填满凹腔110且沉积至持平衬底100的表面，支撑层700成型完毕后，对支撑层700进行机械抛光以及化学抛光以便支撑层700持平衬底100的一面光滑平整，便于后续其它层结构的制作，然后利用磁控溅射的方法制备第一电极层200。在其它的一些实施例中，支撑层700的材质也可以为氮化硅，硅，氮化坦，陶瓷等中的一种或其任意组合。
其中，等离子体增强化学的气相沉积法是借助微波或射频等使含有薄膜成分原子的气体电离，在局部形成等离子体，而等离子体化学活性很强，很容易发生反应，在基片上沉积出所期望的薄膜。为了使化学反应能在较低的温度下进行，利用了等离子体的活性来促进反应，因而这种CVD称为等离子体增强化学气相沉积(PECVD)。而磁控溅射是物理气相沉积(Physical Vapor Deposition，PVD)的一种。一般的溅射法可被用于制备金属、半导体、绝缘体等多材料，且具有设备简单、易于控制、镀膜面积大和附着力强等优点。上世纪70年代发展起来的磁控溅射法更是实现了高速、低温、低损伤。因为是在低气压下进行高速溅射，必须有效地提高气体的离化率。磁控溅射通过在靶阴极表面引入磁场，利用磁场对带电粒子的约束来提高等离子体密度以增加溅射率。
第一电极层200制作好后，在衬底100和第一电极层200的表面上制备压电层300，压电层300贴合衬底100，压电层300将第一电极层200上除与衬底100贴合的一面的其余面覆盖，以使第一电极层200呈嵌设于压电层300贴合衬底100的一面的状态。需说明的是，压电层300的制作方法也是采用磁控溅射的方法。
上面的压电层300制作好后，接着制作第二电极层400，第二电极层400贴合连接压电层300远离衬底100的一面，第二电极层400正对第一电极层200，第一电极层200的制作方法也是采用磁控溅射的方法。
上面第二电极层400制作好后，进行最后的敏感层500制作，敏感层500贴合连接第二电极层400远离压电层300的一面，敏感层500的制作方法也是采用磁控溅射的方法。其中，敏感层500由钯制成，钯制成敏感层500能够大量吸收氢气，因此可以极大地改变谐振器的频率。进一步的，敏感层500的厚度范围在10nm～300nm，本实施例中，敏感层500的厚度 优选为200nm。
如图2至图4所示，第一电极层200与衬底100贴合的一面的面积小于衬底100与第一电极层200贴合的一面的面积的二分之一，第一电极层200的覆盖于衬底100的面积不宜过大。第一电极层200和第二电极层400的厚度和形状均相同，第二电极层400和第一电极层200均由Pt、Mo、Ag、Al、Au中的其中一种制成，第二电极层400的厚度范围在60nm～700nm，其中，第二电极层400和第一电极层200的厚度均优选为100nm。
在一些实施例中，压电层300由氮化铝制成，压电层300的厚度范围在100nm～5μm。本实施例中，压电层300的厚度优选为1000nm。
上述完成后，利用氢氟酸溶液对支撑层700进行释放，至此完成体声波谐振器的制作。
相较于现有技术，本发明实施例通过在第二电极层400上沉积一层由钯制成的敏感层500，钯能够可以大量吸收氢气，因此，利用选择性的通入氮气和氢气，即可实现体声波谐振器的频率移动和恢复，解决现有的体声波谐振器无法调节频率的问题。需说明的是，当第二电极层400和第一电极层200的厚度均为100nm、敏感层500的厚度为200nm、压电层300的厚度为1000nm、凹腔110的深度为2μm时，体声波谐振器频率调节范围较宽，高达1MHz。
此外，本发明实施例还提供一种上述体声波谐振器的制备方法，具体的包括如下步骤：
采用晶面高阻硅制备衬底100，衬底100制作好后，将衬底100先用丙酮浸泡并进行超声清洗，然后经过硫酸和过氧化氢混合溶液清洗完毕后进行干燥处理；
如图1所示，在衬底100的表面制造凹腔110，通过电感耦合等离子体在衬底100的上表面刻蚀以形成一定形状的凹腔110，本实施例中，凹腔110的深度为2um～30um，凹腔110的截面形状为矩形、三角形、梯形中的其中一种；
在凹腔110内形成持平衬底100表面的支撑层700，支撑层700的材质为磷硅玻璃，具体的，利用等离子体增强化学的气相沉积法在凹腔110内沉积一层磷硅玻璃以形成支撑层700，磷硅玻璃填满凹腔110且沉积至持平衬底100的表面，支撑层700成型完毕后，对支撑层700进行机械抛光以及化学抛光以便支撑层700持平衬底100的一面光滑平整，便于后续其它层结构的制作；
在衬底100和支撑层700上采用等离子体增强化学的气相沉积法形成覆盖于凹腔110的第一电极层200，第一电极层200的厚度范围在60nm～700nm，本实施例中，第一电极层200由Pt、Mo、Ag、Al、Au中的其中一种制成，第一电极层200的厚度优选为100nm，且第一电极层200与衬底100贴合的一面的面积小于衬底100与第一电极层200贴合的一面的面积的二分之一；
在衬底100上采用等离子体增强化学的气相沉积法形成压电层300，压电层300的厚度大于第一电极层200，第一电极层200嵌设于压电层300接触衬底100的一面，压电层300由氮化铝制成，压电层300的厚度范围在100nm～5μm，本实施例中，压电层300的厚度优选为1000nm；
在压电层300远离衬底100的一面依次制备第二电极层400、敏感层500，第一电极层200和第二电极层400的厚度和形状均相同，第二电极层400由Pt、Mo、Ag、Al、Au中的其中一种制成，第二电极层400的厚度范围在60nm～700nm，其中，第二电极层400和第一电极层200的厚度均优选为100nm，第二电极层400、敏感层500制作完毕后，利用光刻工艺对压电层300进行图形化处理；
去除支撑层700，利用氢氟酸溶液对支撑层700进行释放，至此，完成体声波谐振器的制作。
上述方法制成的体声波谐振器的频率可调，利用生成的敏感层500的特性来大量吸收氢气，因此，利用选择性的通入氮气和氢气，即可实现体声波谐振器的频率移动和恢复，另外上述制备体声波谐振器的方法也能够与CMOS工艺相兼容，制备工艺简单，无需集成其它的电子元件，极大的节省了生产成本。
上面结合附图对本发明实施例作了详细说明，但是本发明不限于上述实施例，在所述技术领域普通技术人员所具备的知识范围内，还可以在不脱离本发明宗旨的前提下作出各种变化。

Claims (10)

  1. 一种体声波谐振器，其特征在于：包括
    衬底(100)，所述衬底(100)的表面具有凹腔(110)；
    第一电极层(200)，所述第一电极层(200)的一面覆盖于所述凹腔(110)；
    压电层(300)，所述压电层(300)贴合所述衬底(100)，所述压电层(300)将所述第一电极层(200)的其余面覆盖；
    第二电极层(400)，所述第二电极层(400)贴合连接所述压电层(300)远离所述衬底(100)的一面；以及
    敏感层(500)，所述敏感层(500)贴合连接所述第二电极层(400)远离所述压电层(300)的一面。
  2. 根据权利要求1所述的体声波谐振器，其特征在于：所述凹腔(110)的深度为2μm～30μm，所述凹腔(110)的截面形状为矩形、三角形、梯形中的其中一种。
  3. 根据权利要求1所述的体声波谐振器，其特征在于：所述第一电极层(200)与所述衬底(100)贴合的一面的面积小于所述衬底(100)与所述第一电极层(200)贴合的一面的面积的二分之一。
  4. 根据权利要求1所述的体声波谐振器，其特征在于：所述敏感层(500)的厚度范围在10nm～300nm。
  5. 根据权利要求4所述的体声波谐振器，其特征在于：所述敏感层(500)的厚度为200nm。
  6. 根据权利要求1至5中任一所述的体声波谐振器，其特征在于：所述敏感层(500)由钯制成。
  7. 根据权利要求1所述的体声波谐振器，其特征在于：所述压电层(300)由氮化铝制成，所述压电层(300)的厚度范围在100nm～5μm。
  8. 根据权利要求7所述的体声波谐振器，其特征在于：所述压电层(300)的厚度为1000nm。
  9. 根据权利要求1所述的体声波谐振器，其特征在于：所述第一电极层(200)和所述第二电极层(400)的厚度和形状均相同，所述第二电极层(400)和所述第一电极层(200)均由Pt、Mo、Ag、Al、Au中的其中一种制成，所述第二电极层(400)的厚度范围在60nm～700nm。
  10. 一种制备方法，用于制造权利要1至9中任一所述的体声波谐振器，其特征在于， 包括如下步骤：
    采用晶面高阻硅制备衬底(100)；
    在衬底(100)的表面制造凹腔(110)；
    在凹腔(110)内形成持平衬底(100)表面的支撑层(700)，支撑层(700)的材质为磷硅玻璃；
    在衬底(100)和支撑层(700)上形成覆盖于凹腔(110)的第一电极层(200)；
    在衬底(100)上形成压电层(300)，压电层(300)的厚度大于第一电极层(200)，第一电极层(200)嵌设于压电层(300)接触衬底(100)的一面；
    在压电层(300)远离衬底(100)的一面依次制备第二电极层(400)、敏感层(500)；
    去除支撑层(700)。
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