CN114553178A - Bulk acoustic wave resonator having tungsten electrode, filter, and electronic device - Google Patents
Bulk acoustic wave resonator having tungsten electrode, filter, and electronic device Download PDFInfo
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- CN114553178A CN114553178A CN202011332928.1A CN202011332928A CN114553178A CN 114553178 A CN114553178 A CN 114553178A CN 202011332928 A CN202011332928 A CN 202011332928A CN 114553178 A CN114553178 A CN 114553178A
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- WFKWXMTUELFFGS-UHFFFAOYSA-N tungsten Chemical compound [W] WFKWXMTUELFFGS-UHFFFAOYSA-N 0.000 title claims abstract description 99
- 229910052721 tungsten Inorganic materials 0.000 title claims abstract description 99
- 239000010937 tungsten Substances 0.000 title claims abstract description 99
- 239000010410 layer Substances 0.000 claims abstract description 115
- 239000000463 material Substances 0.000 claims abstract description 19
- 229910052751 metal Inorganic materials 0.000 claims abstract description 19
- 239000002184 metal Substances 0.000 claims abstract description 19
- 239000002356 single layer Substances 0.000 claims abstract description 18
- 239000000758 substrate Substances 0.000 claims abstract description 12
- 229910001080 W alloy Inorganic materials 0.000 claims abstract description 9
- PMHQVHHXPFUNSP-UHFFFAOYSA-M copper(1+);methylsulfanylmethane;bromide Chemical compound Br[Cu].CSC PMHQVHHXPFUNSP-UHFFFAOYSA-M 0.000 claims description 21
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- 229910052750 molybdenum Inorganic materials 0.000 description 29
- 239000011733 molybdenum Substances 0.000 description 29
- 230000008878 coupling Effects 0.000 description 17
- 238000010168 coupling process Methods 0.000 description 17
- 238000005859 coupling reaction Methods 0.000 description 17
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- 239000007772 electrode material Substances 0.000 description 10
- 239000010931 gold Substances 0.000 description 10
- 239000010408 film Substances 0.000 description 8
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- 229910052737 gold Inorganic materials 0.000 description 6
- 239000011777 magnesium Substances 0.000 description 6
- 239000010936 titanium Substances 0.000 description 6
- 238000002161 passivation Methods 0.000 description 5
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- 229910052782 aluminium Inorganic materials 0.000 description 4
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 4
- 239000011651 chromium Substances 0.000 description 4
- 239000010949 copper Substances 0.000 description 4
- 229910052741 iridium Inorganic materials 0.000 description 4
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- 229910052697 platinum Inorganic materials 0.000 description 4
- 229910052707 ruthenium Inorganic materials 0.000 description 4
- FYYHWMGAXLPEAU-UHFFFAOYSA-N Magnesium Chemical compound [Mg] FYYHWMGAXLPEAU-UHFFFAOYSA-N 0.000 description 3
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 description 3
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- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 2
- 229910052804 chromium Inorganic materials 0.000 description 2
- 229910052802 copper Inorganic materials 0.000 description 2
- 229910052732 germanium Inorganic materials 0.000 description 2
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- 230000020169 heat generation Effects 0.000 description 2
- 229910052451 lead zirconate titanate Inorganic materials 0.000 description 2
- 238000000034 method Methods 0.000 description 2
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- SYQBFIAQOQZEGI-UHFFFAOYSA-N osmium atom Chemical compound [Os] SYQBFIAQOQZEGI-UHFFFAOYSA-N 0.000 description 2
- 238000010897 surface acoustic wave method Methods 0.000 description 2
- 239000010409 thin film Substances 0.000 description 2
- MAKDTFFYCIMFQP-UHFFFAOYSA-N titanium tungsten Chemical compound [Ti].[W] MAKDTFFYCIMFQP-UHFFFAOYSA-N 0.000 description 2
- WSMQKESQZFQMFW-UHFFFAOYSA-N 5-methyl-pyrazole-3-carboxylic acid Chemical compound CC1=CC(C(O)=O)=NN1 WSMQKESQZFQMFW-UHFFFAOYSA-N 0.000 description 1
- PIGFYZPCRLYGLF-UHFFFAOYSA-N Aluminum nitride Chemical compound [Al]#N PIGFYZPCRLYGLF-UHFFFAOYSA-N 0.000 description 1
- JBRZTFJDHDCESZ-UHFFFAOYSA-N AsGa Chemical compound [As]#[Ga] JBRZTFJDHDCESZ-UHFFFAOYSA-N 0.000 description 1
- 229910052684 Cerium Inorganic materials 0.000 description 1
- 229910052692 Dysprosium Inorganic materials 0.000 description 1
- 229910052691 Erbium Inorganic materials 0.000 description 1
- 229910052693 Europium Inorganic materials 0.000 description 1
- 229910052688 Gadolinium Inorganic materials 0.000 description 1
- 229910001218 Gallium arsenide Inorganic materials 0.000 description 1
- 229910052689 Holmium Inorganic materials 0.000 description 1
- 229910052765 Lutetium Inorganic materials 0.000 description 1
- 229910052779 Neodymium Inorganic materials 0.000 description 1
- 229910052777 Praseodymium Inorganic materials 0.000 description 1
- 229910052773 Promethium Inorganic materials 0.000 description 1
- 229910052772 Samarium Inorganic materials 0.000 description 1
- 229910052581 Si3N4 Inorganic materials 0.000 description 1
- 229910052771 Terbium Inorganic materials 0.000 description 1
- 229910052775 Thulium Inorganic materials 0.000 description 1
- 229910052769 Ytterbium Inorganic materials 0.000 description 1
- XLOMVQKBTHCTTD-UHFFFAOYSA-N Zinc monoxide Chemical compound [Zn]=O XLOMVQKBTHCTTD-UHFFFAOYSA-N 0.000 description 1
- 238000013473 artificial intelligence Methods 0.000 description 1
- 239000000919 ceramic Substances 0.000 description 1
- GWXLDORMOJMVQZ-UHFFFAOYSA-N cerium Chemical compound [Ce] GWXLDORMOJMVQZ-UHFFFAOYSA-N 0.000 description 1
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- 229910052906 cristobalite Inorganic materials 0.000 description 1
- 239000003814 drug Substances 0.000 description 1
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- 238000005516 engineering process Methods 0.000 description 1
- UYAHIZSMUZPPFV-UHFFFAOYSA-N erbium Chemical compound [Er] UYAHIZSMUZPPFV-UHFFFAOYSA-N 0.000 description 1
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- 238000001914 filtration Methods 0.000 description 1
- UIWYJDYFSGRHKR-UHFFFAOYSA-N gadolinium atom Chemical compound [Gd] UIWYJDYFSGRHKR-UHFFFAOYSA-N 0.000 description 1
- 230000017525 heat dissipation Effects 0.000 description 1
- KJZYNXUDTRRSPN-UHFFFAOYSA-N holmium atom Chemical compound [Ho] KJZYNXUDTRRSPN-UHFFFAOYSA-N 0.000 description 1
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- 229910052746 lanthanum Inorganic materials 0.000 description 1
- FZLIPJUXYLNCLC-UHFFFAOYSA-N lanthanum atom Chemical compound [La] FZLIPJUXYLNCLC-UHFFFAOYSA-N 0.000 description 1
- HFGPZNIAWCZYJU-UHFFFAOYSA-N lead zirconate titanate Chemical compound [O-2].[O-2].[O-2].[O-2].[O-2].[Ti+4].[Zr+4].[Pb+2] HFGPZNIAWCZYJU-UHFFFAOYSA-N 0.000 description 1
- GQYHUHYESMUTHG-UHFFFAOYSA-N lithium niobate Chemical compound [Li+].[O-][Nb](=O)=O GQYHUHYESMUTHG-UHFFFAOYSA-N 0.000 description 1
- OHSVLFRHMCKCQY-UHFFFAOYSA-N lutetium atom Chemical compound [Lu] OHSVLFRHMCKCQY-UHFFFAOYSA-N 0.000 description 1
- 229910021421 monocrystalline silicon Inorganic materials 0.000 description 1
- QEFYFXOXNSNQGX-UHFFFAOYSA-N neodymium atom Chemical compound [Nd] QEFYFXOXNSNQGX-UHFFFAOYSA-N 0.000 description 1
- 229910021420 polycrystalline silicon Inorganic materials 0.000 description 1
- 229920005591 polysilicon Polymers 0.000 description 1
- UKDIAJWKFXFVFG-UHFFFAOYSA-N potassium;oxido(dioxo)niobium Chemical compound [K+].[O-][Nb](=O)=O UKDIAJWKFXFVFG-UHFFFAOYSA-N 0.000 description 1
- PUDIUYLPXJFUGB-UHFFFAOYSA-N praseodymium atom Chemical compound [Pr] PUDIUYLPXJFUGB-UHFFFAOYSA-N 0.000 description 1
- 239000000047 product Substances 0.000 description 1
- VQMWBBYLQSCNPO-UHFFFAOYSA-N promethium atom Chemical compound [Pm] VQMWBBYLQSCNPO-UHFFFAOYSA-N 0.000 description 1
- 229910052761 rare earth metal Inorganic materials 0.000 description 1
- KZUNJOHGWZRPMI-UHFFFAOYSA-N samarium atom Chemical compound [Sm] KZUNJOHGWZRPMI-UHFFFAOYSA-N 0.000 description 1
- 229910052594 sapphire Inorganic materials 0.000 description 1
- 239000010980 sapphire Substances 0.000 description 1
- 229910052706 scandium Inorganic materials 0.000 description 1
- SIXSYDAISGFNSX-UHFFFAOYSA-N scandium atom Chemical compound [Sc] SIXSYDAISGFNSX-UHFFFAOYSA-N 0.000 description 1
- 239000004065 semiconductor Substances 0.000 description 1
- 230000035945 sensitivity Effects 0.000 description 1
- 239000000377 silicon dioxide Substances 0.000 description 1
- 229910052682 stishovite Inorganic materials 0.000 description 1
- GZCRRIHWUXGPOV-UHFFFAOYSA-N terbium atom Chemical compound [Tb] GZCRRIHWUXGPOV-UHFFFAOYSA-N 0.000 description 1
- FRNOGLGSGLTDKL-UHFFFAOYSA-N thulium atom Chemical compound [Tm] FRNOGLGSGLTDKL-UHFFFAOYSA-N 0.000 description 1
- 229910052905 tridymite Inorganic materials 0.000 description 1
- NAWDYIZEMPQZHO-UHFFFAOYSA-N ytterbium Chemical compound [Yb] NAWDYIZEMPQZHO-UHFFFAOYSA-N 0.000 description 1
- 229910052727 yttrium Inorganic materials 0.000 description 1
- VWQVUPCCIRVNHF-UHFFFAOYSA-N yttrium atom Chemical compound [Y] VWQVUPCCIRVNHF-UHFFFAOYSA-N 0.000 description 1
Images
Classifications
-
- 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
- H03H9/171—Constructional features of resonators consisting of piezoelectric or electrostrictive material having a single resonator implemented with thin-film techniques, i.e. of the film bulk acoustic resonator [FBAR] type
- H03H9/172—Means for mounting on a substrate, i.e. means constituting the material interface confining the waves to a volume
- H03H9/173—Air-gaps
-
- 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
- H03H9/02007—Details of bulk acoustic wave devices
- H03H9/02015—Characteristics of piezoelectric layers, e.g. cutting angles
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
- H03H9/00—Networks comprising electromechanical or electro-acoustic devices; Electromechanical resonators
- H03H9/15—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
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- Physics & Mathematics (AREA)
- Acoustics & Sound (AREA)
- Piezo-Electric Or Mechanical Vibrators, Or Delay Or Filter Circuits (AREA)
Abstract
The invention relates to a bulk acoustic wave resonator comprising: a substrate; an acoustic mirror; a bottom electrode; a top electrode; and a piezoelectric layer disposed between the bottom electrode and the top electrode, wherein: the piezoelectric layer is a doped piezoelectric layer; and the top electrode and/or the bottom electrode are tungsten electrodes containing metal tungsten. The top and/or bottom electrode is a single layer electrode made of metal tungsten or a single layer electrode made of a tungsten alloy. Or the top electrode and/or the bottom electrode are laminated electrodes, the laminated electrodes comprise at least two electrode layers made of different materials, the at least two electrode layers at least comprise one tungsten electrode layer, and the tungsten electrode layer is an electrode layer made of metal tungsten or an electrode layer made of tungsten alloy. The invention also relates to a filter with the resonator and an electronic device with the filter or the resonator.
Description
Technical Field
Embodiments of the present invention relate to the field of semiconductors, and in particular, to a bulk acoustic wave resonator, a filter having the resonator, and an electronic device having the resonator or the filter.
Background
Electronic devices have been widely used as basic elements of electronic equipment, and their application ranges include mobile phones, automobiles, home electric appliances, and the like. In addition, technologies such as artificial intelligence, internet of things, 5G communication and the like which will change the world in the future still need to rely on electronic devices as a foundation.
Electronic devices can exert different characteristics and advantages according to different working principles, and among all electronic devices, devices working by utilizing the piezoelectric effect (or inverse piezoelectric effect) are an important class, and the piezoelectric devices have very wide application scenarios. Film Bulk Acoustic Resonator (FBAR, also called Bulk Acoustic Resonator, BAW for short) is playing an important role in the communication field as an important member of piezoelectric devices, and especially, FBAR filters have good characteristics of small size, high resonant frequency, high quality factor, large power capacity, good roll-off effect and the like as market share in the field of radio frequency filters is larger, and the filters gradually replace traditional Surface Acoustic Wave (SAW) filters and ceramic filters, play a great role in the field of radio frequency of wireless communication, and have the advantage of high sensitivity and can also be applied to sensing fields of biology, physics, medicine and the like.
A schematic cross-sectional view of a conventional film bulk acoustic resonator is shown in fig. 1, for example, the material of the bottom electrode 30 and the top electrode 50 is molybdenum, and the material of the piezoelectric layer 40 is aluminum nitride. The bottom electrode 30 and the top electrode 50 are equal in thickness t and the piezoelectric layer 40 is equal in thickness d. The thickness ratio t/d of the single-layer electrode to the piezoelectric layer thickness influences the effective electromechanical coupling coefficient of the resonator, and further influences the bandwidth of the resonator (the larger the effective electromechanical coupling coefficient is, the larger the bandwidth is). The impedance of the film bulk acoustic resonator needs to be matched to 50 ohms in design, and the thinner the piezoelectric layer thickness is, the smaller the area A of an effective region can be under the same frequency and bandwidth, so that the more resonators are integrated on a single wafer, and the manufacturing cost can be saved.
The common method for reducing the thickness of the piezoelectric layer is to adopt scandium-doped aluminum nitride as the piezoelectric layer, so that the electromechanical coupling coefficient of the piezoelectric layer is increased, and when the same bandwidth is required, the larger ratio t/d of the thickness of a single-layer electrode to the thickness of the piezoelectric layer can be adopted, so that the purpose of reducing the thickness of the piezoelectric layer is achieved, and the area A of a resonator can be reduced by matching 50 ohms.
However, the above method has problems that: the reduction in area results in a smaller power capacity for the resonator at the same power density.
Disclosure of Invention
The invention is provided in order to not only reduce the area of the effective area of the resonator, but also ensure the power capacity of the resonator, for example, in order to solve the problem that the power capacity is deteriorated because the area of the effective area of the resonator is reduced after scandium-doped aluminum nitride is introduced as a piezoelectric layer.
According to an aspect of an embodiment of the present invention, there is provided a bulk acoustic wave resonator including:
a substrate;
an acoustic mirror;
a bottom electrode;
a top electrode; and
a piezoelectric layer disposed between the bottom electrode and the top electrode,
wherein:
the piezoelectric layer is a doped piezoelectric layer; and is
The top electrode and/or the bottom electrode are tungsten electrodes containing metal tungsten.
Optionally, the top electrode and/or the bottom electrode is a single-layer electrode made of metal tungsten or a single-layer electrode made of tungsten alloy.
Or optionally, the top electrode and/or the bottom electrode are stacked electrodes, the stacked electrodes include at least two stacked electrode layers made of different materials, the at least two electrode layers include at least one tungsten electrode layer, and the tungsten electrode layer is an electrode layer made of metal tungsten or an electrode layer made of tungsten alloy.
Embodiments of the present invention also relate to a filter comprising the bulk acoustic wave resonator described above.
Embodiments of the invention also relate to an electronic device comprising a filter as described above or a resonator as described above.
Drawings
These and other features and advantages of the various embodiments of the disclosed invention will be better understood from the following description taken in conjunction with the accompanying drawings, in which like reference characters designate like parts throughout the figures thereof, and in which:
FIG. 1 is a schematic cross-sectional view of a conventional film bulk acoustic resonator;
fig. 2 is a graph schematically showing the relationship between the ratio of the thickness of the single-layer electrode to the thickness of the piezoelectric layer and the electromechanical coupling coefficient of the resonator in the case where the thicknesses of the top electrode and the bottom electrode are the same, wherein three cases of the piezoelectric layer being aluminum nitride and the electrodes being molybdenum, the piezoelectric layer being scandium-doped aluminum nitride and the electrodes being tungsten are shown respectively;
figures 3-12 show schematic cross-sectional views of bulk acoustic wave resonators of different embodiments of the present invention, respectively.
Detailed Description
The technical scheme of the invention is further specifically described by the following embodiments and the accompanying drawings. In the specification, the same or similar reference numerals denote the same or similar components. The following description of the embodiments of the present invention with reference to the accompanying drawings is intended to explain the general inventive concept of the present invention and should not be construed as limiting the invention.
As known to those skilled in the art, the doped piezoelectric layer is used instead of the piezoelectric layer, and the area of the active area of the resonator becomes smaller and smaller under the same electromechanical coupling coefficient and frequency, so that the power capacity of the resonator becomes smaller under the same power density.
Furthermore, as known to those skilled in the art, if the molybdenum electrodes of the resonator are replaced by tungsten electrodes under the same electromechanical coupling coefficient and frequency, the area of the active area of the resonator becomes small, which is not favorable for maintaining a large power capacity.
In addition, as known to those skilled in the art, the film resistivity of metal tungsten at room temperature is 20 to 30 micro-ohm per centimeter, and the film resistivity of metal molybdenum at room temperature is about 10 micro-ohm per centimeter, and it can be seen that the film resistivity of metal tungsten at room temperature is much greater than the film resistivity of metal molybdenum at room temperature. Therefore, it is generally considered that the resistance of a tungsten electrode using tungsten as an electrode during the operation of the resonator is larger than that of a molybdenum electrode using molybdenum as an electrode, so that the heat generation of the tungsten electrode due to the current flowing through the resistance is larger than that of the molybdenum electrode. In this case, the replacement of the molybdenum electrode of the resonator by the tungsten electrode directly leads to an increase in heat dissipation of the electrode of the resonator during operation, which is disadvantageous for maintaining a large power capacity with a constant area of the active area of the resonator. Therefore, the skilled person would not think to replace the molybdenum electrodes of the resonator with tungsten electrodes, based on maintaining a large power capacity.
Based on the above, for resonators using molybdenum electrodes and doped piezoelectric layers (which already have a small active area based on doping), it is common practice for those skilled in the art to avoid replacing the molybdenum electrodes with tungsten electrodes in resonators using molybdenum electrodes and doped piezoelectric layers as much as possible, since the use of tungsten electrodes further reduces the active area and is not conducive to maintaining good power capability.
However, the inventors have found that, if the molybdenum electrode in a resonator using a molybdenum electrode and a doped piezoelectric layer is replaced with a tungsten electrode, the power capacity of the resonator can be ensured while the area of the effective region of the resonator is reduced.
Based on the above, the present invention proposes a technical solution of combining a doped piezoelectric layer (which can reduce the area of the effective area of the resonator) with a tungsten electrode (which can reduce the area of the effective area of the resonator) in a bulk acoustic wave resonator.
The technical means of the present invention will be described in detail below with reference to FIGS. 2 to 12. In the present invention, reference numerals are briefly described as follows:
110. 210, 310: the substrate can be selected from monocrystalline silicon, quartz, gallium arsenide or sapphire.
120. 220, 320: the acoustic mirror, which is located on the upper surface of the substrate 110 or embedded inside the substrate, is formed by a cavity embedded in the substrate in the present invention, but the acoustic mirror may be a bragg reflection layer and other equivalent forms.
130. 230, 240, 330, 340, 350: a single layer bottom electrode or one of the bottom electrode layers in the bottom electrode stack may be deposited on the upper surface of the acoustic mirror and cover the acoustic mirror. The bottom electrode 130 may be beveled and aligned with the active area edge of the resonator, and the bottom electrode 130 may have a stepped, vertical or similar edge. The material of the bottom electrode may be: gold (Au), tungsten (W), molybdenum (Mo), platinum (Pt), ruthenium (Ru), iridium (Ir), titanium Tungsten (TiW), aluminum (Al), titanium (Ti), osmium (Os), magnesium (Mg), gold (Au), tungsten (W), molybdenum (Mo), platinum (Pt), ruthenium (Ru), iridium (Ir), germanium (Ge), copper (Cu), aluminum (Al), chromium (Cr), arsenic-doped gold and the like, and alloys thereof, and the like.
140. 250, 360: the piezoelectric thin film layer or the piezoelectric layer can be selected from aluminum nitride (AlN), zinc oxide (ZnO), lead zirconate titanate (PZT), and lithium niobate (LiNbO) which comprise rare earth element doped materials with certain atomic ratio3) Quartz (Quartz), potassium niobate (KNbO)3) Or lithium tantalate (LiTaO)3) Etc., doping elements such as scandium (Sc), yttrium (Y), magnesium (Mg), titanium (Ti), lanthanum (La), cerium (Ce), praseodymium (Pr), neodymium (Nd), promethium (Pm), samarium (Sm), europium (Eu), gadolinium (Gd), terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb), lutetium (Lu), etc.
150. 260, 270, 370, 380, 390: the single top electrode or one of the top electrode layers in the top electrode stack may be made of: gold (Au), tungsten (W), molybdenum (Mo), platinum (Pt), ruthenium (Ru), iridium (Ir), titanium Tungsten (TiW), aluminum (Al), titanium (Ti), osmium (Os), magnesium (Mg), gold (Au), tungsten (W), molybdenum (Mo), platinum (Pt), ruthenium (Ru), iridium (Ir), germanium (Ge), copper (Cu), aluminum (Al), chromium (Cr), arsenic-doped gold and the like, and alloys thereof, and the like. The top electrode may be the same or different material than the bottom electrode. In fig. 2, the passivation layer is not disposed over the top electrode, but may be disposed as well, as can be appreciated.
160: passivation layer, passivation layer material including but not limited to polysilicon SiO2、Si3N4AlN and the like.
170: the material of the bump structure is the same as the top electrode 130 or the bottom electrode 150 or the piezoelectric layer 140. The protruding structure is located at the edge of the effective area, and the protruding structure can reduce the acoustic impedance of the effective area where the protruding structure is located. In one embodiment of the present invention, the material of the protruding structure is metal tungsten.
A schematic cross-sectional view of a bulk acoustic wave resonator according to the present invention is also shown in fig. 1. In one specific example, the material of the bottom electrode 30 and the top electrode 50 of the resonator is molybdenum and the material of the piezoelectric layer 40 is scandium-doped aluminum nitride. The bottom electrode 30 and the top electrode 50 are equal in thickness t and the piezoelectric layer 40 is equal in thickness d. The thickness ratio (thickness ratio) t/d of the single-layer electrode to the piezoelectric layer can affect the effective electromechanical coupling coefficient of the resonator, and further affect the bandwidth of the resonator (the larger the effective electromechanical coupling coefficient is, the larger the bandwidth is).
Fig. 2 is a graph schematically showing the relationship between the ratio of the thickness of the single-layer electrode to the thickness of the piezoelectric layer and the electromechanical coupling coefficient of the resonator in the case where the thicknesses of the top electrode and the bottom electrode are the same, in which three cases of the piezoelectric layer being aluminum nitride and the electrodes being molybdenum, the piezoelectric layer being scandium-doped aluminum nitride and the electrodes being tungsten are shown, respectively.
As shown in FIG. 2, assuming that the bottom electrode 30 and the top electrode 50 have the same thickness, the abscissa is the thickness ratio t/d of the single-layer electrode to the piezoelectric layer thickness, and the ordinate is the effective electromechanical coupling coefficient (Kt) of the resonator2eff), the effective electromechanical coupling coefficient when the solid line is molybdenum as the bottom electrode and the top electrode, and the piezoelectric layer is aluminum nitride; the dotted line is the effective electromechanical coupling coefficient when the bottom electrode and the top electrode are molybdenum and the piezoelectric layer is 3% scandium-doped aluminum nitride, and the curve of the effective electromechanical coupling coefficient is integrally improved; the chain line is the effective electromechanical coupling coefficient when the bottom electrode and the top electrode are made of tungsten and the piezoelectric layer is made of 3% scandium-doped aluminum nitride, and the curve of the effective electromechanical coupling coefficient is integrally further improved. The traditional bulk acoustic wave resonator uses molybdenum as an electrode, when the piezoelectric layer adopts scandium-doped aluminum nitride, under the same frequency, compared with the condition that the piezoelectric layer is aluminum nitride, the thickness ratio t/d of the electrode to the thickness of the piezoelectric layer is increased, the thickness of the electrode is thickened, the thickness of the piezoelectric layer is thinned, the area A required by matching 50 ohms is smaller, the purpose of reducing the area A of an effective area to increase the number of resonators can be achieved, and therefore the manufacturing cost is reduced, but the manufacturing cost is reducedReducing the area a also deteriorates the power capacity of the resonator.
In the invention, the tungsten electrode is used for replacing the molybdenum electrode, on one hand, the heat conductivity coefficient (1.73) of the tungsten electrode is greater than that of the molybdenum electrode (1.38), and the heat conductivity of the tungsten electrode is better, so that the resonator can bear higher power density and can have higher power capacity; on the other hand, the tungsten electrode can further improve the effective electromechanical coupling coefficient, when the effective electromechanical coupling coefficient is the same, the thickness ratio t/d of the thickness of the electrode to that of the piezoelectric layer can be larger, the thickness of the tungsten electrode is increased to reduce the resistance of the thin film electrode and reduce the heat generation of the electrode resistance relative to the molybdenum electrode, and the heat conductivity of the electrode material is better than that of the piezoelectric layer material, so that the resonator can bear higher power density and higher power capacity.
Therefore, in the present invention, using tungsten electrodes in a resonator having a scandium-doped aluminum nitride piezoelectric layer, the power capacity of the resonator can be ensured while reducing the area a of the effective area of the resonator. Scandium-doped aluminum nitride is used as the piezoelectric layer, tungsten is used as the electrode material, the area of the resonator can be reduced, the number of resonators integrated by a single wafer is increased, the power capacity of the resonator can be ensured, and the resonator is not damaged under high power.
Various embodiments of the present invention are illustrated below with reference to fig. 3-12.
As shown in fig. 3, in an embodiment of the present invention, the bottom electrode 130 and the top electrode 150 are tungsten electrodes and have the same thickness (t1 ═ t2), and the piezoelectric layer 140 is aluminum nitride or other piezoelectric material with different doping concentrations.
In an alternative embodiment, in the structure shown in fig. 3, the bottom electrode 130 and the top electrode 150 are tungsten electrodes but have different thicknesses (t1> t2 or t1< t2), and the piezoelectric layer 140 is aluminum nitride or other piezoelectric material with different doping concentrations.
In an alternative embodiment, in the structure shown in fig. 3, the bottom electrode 130 is a tungsten electrode, the top electrode 150 is a molybdenum electrode or other electrode material, the thicknesses of the top electrode and the bottom electrode are the same or different (t1 ═ t2 or t1> t2 or t1< t2), and the piezoelectric layer 140 is aluminum nitride or other piezoelectric material with different doping concentrations.
In an alternative embodiment, in the structure shown in fig. 3, the bottom electrode 130 is a molybdenum electrode or other electrode material, the top electrode 150 is a tungsten electrode, and the thicknesses are the same or different (t1 ═ t2 or t1> t2 or t1< t2), and the piezoelectric layer 140 is aluminum nitride or other piezoelectric material with different doping concentrations.
The structure shown in fig. 4 is similar to that of fig. 3, except that in fig. 4, a passivation layer 160 is added to the top electrode 150.
The structure shown in fig. 5 is similar to that of fig. 3, except that in fig. 5, a raised structure 170 is added to the top electrode 150.
The structure shown in fig. 6 is similar to that of fig. 5, except that in fig. 6, a raised structure 170 and a passivation layer 160 have been added to the top electrode 150.
In the structures shown in fig. 3 to 6, the top electrode or the bottom electrode has a single-layer electrode structure, but the present invention is not limited thereto. The electrodes may have a stacked structure, and in this case, one of the electrode layers in the stacked structure may be a tungsten electrode layer. Figures 7-12 show resonator embodiments with stacked electrodes. The following is an exemplary illustration:
in fig. 7, the top electrode is composed of a stacked structure of a first top electrode 260 and a second top electrode 270, and the bottom electrode is composed of a stacked structure of a first bottom electrode 240 and a second bottom electrode 230, wherein 260 and 240 are tungsten electrodes, and 270 and 230 may be other electrode material layers.
The structure shown in fig. 8 is similar to that shown in fig. 7, except that the top electrode in fig. 8 is shown as 260, where 260 and 240 are tungsten electrodes, and 230 can be other electrode material layers.
The structure shown in fig. 9 is similar to that shown in fig. 7, except that the bottom electrode in fig. 9 is only 240, where 260 and 240 are tungsten electrodes, and 270 can be other electrode material layers.
In fig. 10, the top electrode is composed of a stacked structure of a first top electrode 370, a second top electrode 380, and a third top electrode 390, and the bottom electrode is composed of a stacked structure of a first bottom electrode 350, a second bottom electrode 340, and a third bottom electrode 330, wherein 370 and 350 are tungsten electrodes, 330, 340, 380, and 390 may be other electrode material layers, and 330 and 390 may still be tungsten electrodes.
The structure shown in fig. 11 is similar to that of fig. 10, except that the top electrode in fig. 11 is only 370, where 370 and 350 are tungsten electrodes, 330, 340 may be other layers of electrode material, and 330 may be a tungsten electrode.
The structure shown in fig. 12 is similar to that of fig. 10, except that the bottom electrode in fig. 12 is only 240, where 370 and 350 are tungsten electrodes, 380, 390 may be other electrode materials, and 390 may be a tungsten electrode.
In the embodiments shown in fig. 7 to 12, the tungsten electrode layers are provided on both upper and lower sides of the piezoelectric layer, but the present invention is not limited thereto, and for example, the tungsten electrode layers may be provided only on one side of the piezoelectric layer.
In the above-described embodiments of the present invention, the tungsten electrode or the tungsten electrode layer is formed by using metal tungsten, but the present invention is not limited thereto, and the tungsten electrode or the tungsten electrode layer may be formed by using a tungsten alloy (i.e., an alloy containing metal tungsten), which is within the scope of the present invention.
It is to be noted that, in the present invention, each numerical range, except when explicitly indicated as not including the end points, can be either the end points or the median of each numerical range, and all fall within the scope of the present invention.
In the present invention, the upper and lower are with respect to the bottom surface of the base of the resonator, and with respect to one component, the side thereof close to the bottom surface is the lower side, and the side thereof far from the bottom surface is the upper side.
In the present invention, the inner and outer are in the lateral direction or the radial direction with respect to the center of the effective area of the resonator (i.e., the effective area center), one side or one end of a component close to the effective area center is the inner side or the inner end, and one side or one end of the component away from the effective area center is the outer side or the outer end. For a reference position, being inside of the position means being between the position and the center of the effective area in the lateral or radial direction, and being outside of the position means being further away from the center of the effective area than the position in the lateral or radial direction.
As can be appreciated by those skilled in the art, the bulk acoustic wave resonator according to the present invention may be used to form a filter or an electronic device. The electronic device includes, but is not limited to, intermediate products such as a radio frequency front end and a filtering and amplifying module, and terminal products such as a mobile phone, WIFI and an unmanned aerial vehicle.
Based on the above, the invention provides the following technical scheme:
1. a bulk acoustic wave resonator comprising:
a substrate;
an acoustic mirror;
a bottom electrode;
a top electrode; and
a piezoelectric layer disposed between the bottom electrode and the top electrode,
wherein:
the piezoelectric layer is a doped piezoelectric layer; and is
The top electrode and/or the bottom electrode are tungsten electrodes containing metal tungsten.
2. The resonator of claim 1, wherein:
the top and/or bottom electrode is a single layer electrode made of metal tungsten or a single layer electrode made of a tungsten alloy.
3. The resonator of claim 2, wherein:
the top electrode and the bottom electrode are both tungsten electrodes; and is
The ratio of the monolayer thickness of the top or bottom electrode to the thickness of the doped piezoelectric layer is in the range of 0.1-1.
4. The resonator of claim 2, wherein:
the top electrode and the bottom electrode are both tungsten electrodes;
the non-electrode connecting ends of the bottom electrodes are all located outside the boundary of the acoustic mirror in the horizontal direction and form thermal contact with the substrate.
5. The resonator of claim 2, wherein:
one tungsten electrode and the other non-tungsten electrode are arranged in the top electrode and the bottom electrode, and the thickness of the tungsten electrode is different from that of the non-tungsten electrode; or
One tungsten electrode and the other non-tungsten electrode are arranged in the top electrode and the bottom electrode, and the thickness of the tungsten electrode is equal to that of the non-tungsten electrode.
6. The resonator of claim 1, wherein:
the top electrode and/or the bottom electrode are laminated electrodes, the laminated electrodes comprise at least two electrode layers which are laminated and made of different materials, the at least two electrode layers at least comprise a tungsten electrode layer, and the tungsten electrode layer is an electrode layer made of metal tungsten or an electrode layer made of tungsten alloy.
7. The resonator of claim 6, wherein:
and an electrode layer of the laminated electrode, which is adjacent to the piezoelectric layer, is a first electrode layer, and the first electrode layer is a tungsten electrode layer.
8. The resonator of claim 7, wherein:
the top electrode and the bottom electrode are both laminated electrodes.
9. The resonator of claim 8, wherein:
the non-electrode connecting ends of the bottom electrodes are all located outside the boundary of the acoustic mirror in the horizontal direction and form thermal contact with the substrate.
10. The resonator of claim 7, wherein:
one of the top electrode and the bottom electrode is a laminated electrode, and the other is a non-laminated electrode.
11. The resonator of any of claims 1-10, wherein:
the piezoelectric layer is scandium-doped aluminum nitride.
12. The resonator of any of claims 1-10, wherein:
the resonator further comprises a protruding structure arranged along the active area, and the protruding structure is made of tungsten.
13. A filter comprising a bulk acoustic wave resonator according to any one of claims 1-12.
14. An electronic device comprising a filter according to 13 or a resonator according to any of claims 1-12.
Although embodiments of the present invention have been shown and described, it would be appreciated by those skilled in the art that changes may be made in these embodiments without departing from the principles and spirit of the invention, the scope of which is defined in the claims and their equivalents.
Claims (14)
1. A bulk acoustic wave resonator comprising:
a substrate;
an acoustic mirror;
a bottom electrode;
a top electrode; and
a piezoelectric layer disposed between the bottom electrode and the top electrode,
wherein:
the piezoelectric layer is a doped piezoelectric layer; and is
The top electrode and/or the bottom electrode are tungsten electrodes containing metal tungsten.
2. The resonator of claim 1, wherein:
the top and/or bottom electrode is a single layer electrode made of metal tungsten or a single layer electrode made of a tungsten alloy.
3. The resonator of claim 2, wherein:
the top electrode and the bottom electrode are both tungsten electrodes; and is
The ratio of the monolayer thickness of the top or bottom electrode to the thickness of the doped piezoelectric layer is in the range of 0.1-1.
4. The resonator of claim 2, wherein:
the top electrode and the bottom electrode are both tungsten electrodes;
the non-electrode connecting ends of the bottom electrodes are all located outside the boundary of the acoustic mirror in the horizontal direction and form thermal contact with the substrate.
5. The resonator of claim 2, wherein:
one tungsten electrode and the other non-tungsten electrode are arranged in the top electrode and the bottom electrode, and the thickness of the tungsten electrode is different from that of the non-tungsten electrode; or
One tungsten electrode and the other non-tungsten electrode are arranged in the top electrode and the bottom electrode, and the thickness of the tungsten electrode is equal to that of the non-tungsten electrode.
6. The resonator of claim 1, wherein:
the top electrode and/or the bottom electrode are laminated electrodes, each laminated electrode comprises at least two electrode layers which are laminated and made of different materials, each electrode layer at least comprises a tungsten electrode layer, and each tungsten electrode layer is an electrode layer made of metal tungsten or an electrode layer made of tungsten alloy.
7. The resonator of claim 6, wherein:
and an electrode layer of the laminated electrode, which is adjacent to the piezoelectric layer, is a first electrode layer, and the first electrode layer is a tungsten electrode layer.
8. The resonator of claim 7, wherein:
the top electrode and the bottom electrode are both laminated electrodes.
9. The resonator of claim 8, wherein:
the non-electrode connecting ends of the bottom electrodes are all located outside the boundary of the acoustic mirror in the horizontal direction and form thermal contact with the substrate.
10. The resonator of claim 7, wherein:
one of the top electrode and the bottom electrode is a laminated electrode, and the other is a non-laminated electrode.
11. The resonator of any of claims 1-10, wherein:
the piezoelectric layer is scandium-doped aluminum nitride.
12. The resonator of any of claims 1-10, wherein:
the resonator further comprises a protruding structure arranged along the active area, and the protruding structure is made of tungsten.
13. A filter comprising the bulk acoustic wave resonator according to any one of claims 1-12.
14. An electronic device comprising a filter according to claim 13 or a resonator according to any of claims 1-12.
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| CN202011332928.1A CN114553178A (en) | 2020-11-24 | 2020-11-24 | Bulk acoustic wave resonator having tungsten electrode, filter, and electronic device |
| PCT/CN2021/132122 WO2022111415A1 (en) | 2020-11-24 | 2021-11-22 | Bulk acoustic resonator having tungsten electrode, filter, and electronic device |
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| US9548438B2 (en) * | 2014-03-31 | 2017-01-17 | Avago Technologies General Ip (Singapore) Pte. Ltd. | Acoustic resonator comprising acoustic redistribution layers |
| CN110868185B (en) * | 2019-04-23 | 2024-04-16 | 中国电子科技集团公司第十三研究所 | Bulk acoustic wave resonator and semiconductor device |
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