CN116436432A - Miniaturized surface acoustic wave filter structure - Google Patents
Miniaturized surface acoustic wave filter structure Download PDFInfo
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- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
- H03H9/00—Networks comprising electromechanical or electro-acoustic devices; Electromechanical resonators
- H03H9/02—Details
- H03H9/02535—Details of surface acoustic wave devices
- H03H9/02543—Characteristics of substrate, 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
- H03H9/02—Details
- H03H9/02535—Details of surface acoustic wave devices
- H03H9/02614—Treatment of substrates, e.g. curved, spherical, cylindrical substrates ensuring closed round-about circuits for the acoustical waves
-
- 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
- H03H9/02535—Details of surface acoustic wave devices
- H03H9/02818—Means for compensation or elimination of undesirable effects
- H03H9/02834—Means for compensation or elimination of undesirable effects of temperature influence
Abstract
The invention discloses a miniaturized surface acoustic wave filter structure, which comprises a piezoelectric substrate and an electrode layer, and is characterized by further comprising an insulating layer, wherein the insulating layer is positioned between the piezoelectric substrate and the electrode layer and completely separates the piezoelectric substrate and the electrode layer, and the insulating layer covers part of the surface of the piezoelectric substrate. The scheme can excite a low sound velocity acoustic wave mode, and the sound velocity excited by the mode can be reduced to 900m/S, so that the miniaturized design requirements of the P-band, L-band and S-band SAW devices are met, and the miniaturized design of the devices is realized.
Description
Technical Field
The invention relates to the technical field of surface acoustic wave devices, in particular to a miniaturized surface acoustic wave filter structure.
Background
As a basis and key for mobile communications, radio frequency front ends are a core component of radar, satellite communications electronics, and mobile terminal products. The radio frequency front-end filter is used for filtering various interference signals such as various parasitic clutters, noise and the like and mainly comprises a filter/duplexer, a power amplifier, a tag and other device units. The Surface Acoustic Wave (SAW) filter has the characteristics of small volume, good consistency, high reliability, low loss, good filtering performance and the like, and has become the most mainstream radio frequency front-end filter of military radars, satellite communication electronics, mobile terminals and the like.
A surface acoustic wave (surface acoustic wave, SAW) sensor is a new type of micro-acoustic sensor developed in recent years, and is a sensor that uses a surface acoustic wave device as a sensing element, reflects measured information by a change in the speed or frequency of a surface acoustic wave in the surface acoustic wave device, and converts the information into an electrical signal output.
The prior art SAW filter generally comprises a piezoelectric substrate and an electrode layer, wherein the electrode layer is generally two interdigital electrodes, and the electrode layer is directly coated on the surface of the piezoelectric substrate, wherein the material of the piezoelectric substrate is generally lithium tantalate (LiTaO) 3 ) Lithium niobate (LiNbO) 3 ) And the like, the acoustic surface wave filter manufactured by adopting the structure and the materials is excited into a high sound velocity acoustic wave mode, the sound velocity of the acoustic surface wave filter is generally between 3500m/S and 4500m/S, however, the design of SAW devices of P wave band, L wave band, S wave band and the like is mainly a low sound velocity acoustic wave mode (1800 m/S to 3200 m/S), so the traditional acoustic surface wave filter structure greatly limits the miniaturization design of the SAW devices of P wave band, L wave band and S wave band.
Disclosure of Invention
Aiming at the defects existing in the prior art, the invention aims to solve the technical problems that: how to provide a surface acoustic wave filter structure which can effectively excite low sound velocity acoustic wave modes and further realize the miniaturization design of SAW devices under P wave band, L wave band and S wave band.
In order to solve the technical problems, the invention adopts the following technical scheme:
a miniaturized surface acoustic wave filter structure includes a piezoelectric substrate and an electrode layer, and further includes an insulating layer between the piezoelectric substrate and the electrode layer, which completely separates the piezoelectric substrate and the electrode layer, and which partially covers a surface of the piezoelectric substrate.
Preferably, a first insulating layer and a second insulating layer are respectively arranged on the piezoelectric substrate along the axial direction, the axial distance between the first insulating layer and the second insulating layer is greater than 0, a first electrode layer is arranged on the first insulating layer, the width of the first insulating layer is greater than that of the first electrode layer, a second electrode layer is arranged on the second insulating layer, and the width of the second insulating layer is greater than that of the second electrode layer.
Preferably, the piezoelectric element further comprises an upper temperature compensation layer, wherein the upper temperature compensation layer is made of a material with a positive temperature coefficient, the temperature compensation layer is positioned on the surface of the piezoelectric substrate, and the upper temperature compensation layer completely covers the insulating layer and the electrode layer.
Preferably, the piezoelectric thin film layer is positioned between the piezoelectric substrate and the insulating layer, the piezoelectric thin film layer completely covers the surface of the piezoelectric substrate, and the insulating layer partially covers the surface of the piezoelectric thin film layer.
Preferably, the piezoelectric thin film structure further comprises a lower temperature compensation layer, wherein the lower temperature compensation layer is positioned between the piezoelectric substrate and the piezoelectric thin film layer, the lower temperature compensation layer is made of a material with a positive temperature coefficient, the lower temperature compensation layer completely covers the surface of the piezoelectric substrate, and the piezoelectric thin film layer completely covers the surface of the lower temperature compensation layer.
Preferably, the piezoelectric thin film further comprises an upper temperature compensation layer, the upper temperature compensation layer is made of a material with a positive temperature coefficient, the upper temperature compensation layer is located on the surface of the piezoelectric thin film layer, and the upper temperature compensation layer completely covers the insulating layer and the electrode layer.
Compared with the prior art, the invention has the following advantages:
1. according to the invention, the insulating layer is arranged between the electrode layer and the piezoelectric substrate, so that the piezoelectric substrate and the electrode layer are completely separated, and meanwhile, the insulating layer only covers part of the surface of the piezoelectric substrate, so that the surface of the piezoelectric substrate covered by the insulating layer is a free interface, and the surface of the piezoelectric substrate uncovered by the insulating layer is a free interface, so that the structure of the scheme is more complex than that of a traditional structural device, and the scheme relates to Rayleigh waves, leaky surface waves, longitudinal leaky surface waves, love waves, sishawatts and various bulk waves, and interaction and mode conversion of different acoustic wave modes exist, namely, the acoustic field distribution and the electric field distribution of the whole structure are different, and as a result, the excitation conditions of each acoustic surface mode, each acoustic surface mode and the acoustic wave mode performance are changed, meanwhile, the low acoustic velocity mode can be excited through the structure, and the excited acoustic velocity can be reduced to 900m/S, thereby meeting the requirements of the miniaturized design of P-band, L-S-band SAW devices, and realizing the miniaturized design of the devices.
2. The invention can restrain the parasitic of clutter modes of each order by optimizing the piezoelectric material and the thickness of tangential and film structures, is beneficial to realizing the low-temperature drift and high rectangular performance of the surface acoustic wave filter, and simultaneously, the structure can be beneficial to developing a high-performance narrow-band filter, thereby meeting the requirements of terminals such as high-speed mobile communication on the low-temperature drift and high rectangular surface acoustic wave filter, and the preparation process used by the structure is easy to realize and easy to popularize on a large scale.
3. According to the invention, due to the existence of the insulating layer and the temperature compensation layer, when the temperature of the electrode layer generates larger deformation due to thermal expansion and contraction, the electrode layer does not directly act on the surface of the piezoelectric substrate, so that the temperature sensitivity of the whole device is not greatly influenced, the temperature stability of the surface acoustic wave filter is greatly improved, and the temperature stability of the surface acoustic wave filter can be further improved due to the design of the temperature compensation layer, so that the design of the surface acoustic wave filter with high temperature stability is realized.
4. Due to the existence of the insulating layer, partial sound waves can be reflected through the insulating layer before the sound waves are incident on the piezoelectric substrate layer, so that the sound waves incident inside the piezoelectric substrate are reduced, and the Q value (quality factor) of the surface acoustic wave filter is improved.
5. The system eigenequation of the surface acoustic wave filter is the most complex in each acoustic branch, the eigenequation describing the propagation characteristics adopts a more complex tensor, the special force electric coupling of a heterogeneous integrated structure and complex boundary conditions, the solution of the equation is more complex than that of the surface acoustic wave filter with a traditional structure, the equation relates to Rayleigh waves, surface leakage waves, longitudinal surface leakage waves, love waves, sishin tiles and various bulk waves, and interaction and mode conversion of different acoustic wave modes exist, namely, the sound field distribution and the electric field distribution of the whole surface acoustic wave filter are different, and as a result, each acoustic surface mode excitation condition and acoustic wave mode performance are changed.
Drawings
Fig. 1 is a schematic diagram of a prior art surface acoustic wave filter;
fig. 2 is a schematic structural diagram of a miniaturized surface acoustic wave filter structure and a schematic acoustic wave propagation interface according to an embodiment of the present invention;
FIG. 3 is a graph showing the performance of a miniaturized SAW filter structure having different electrode layer thicknesses in accordance with an embodiment of the present invention;
FIG. 4 is a graph showing the performance of a miniaturized SAW filter structure having different insulating layer thicknesses in accordance with an embodiment of the present invention;
Fig. 5 is an admittance curve of a miniaturized saw filter structure in accordance with an embodiment of the present invention;
fig. 6 is a schematic structural diagram of a miniaturized surface acoustic wave filter structure and a schematic acoustic wave propagation interface in accordance with a second embodiment of the present invention;
FIG. 7 is a graph showing the performance of a miniaturized SAW filter structure having different upper temperature patch thicknesses in accordance with the second embodiment of the present invention;
FIG. 8 is a graph showing the performance of a miniaturized SAW filter structure having different electrode layer thicknesses in accordance with the second embodiment of the present invention;
fig. 9 is a performance curve of a miniaturized saw filter structure with different insulating layer thicknesses in the second embodiment of the present invention;
fig. 10 is an admittance curve of a miniaturized surface acoustic wave filter structure in accordance with the second embodiment of the present invention;
fig. 11 is a schematic structural diagram of a miniaturized surface acoustic wave filter structure and a schematic acoustic wave propagation interface in accordance with a third embodiment of the present invention;
FIG. 12 is a graph showing the performance of a miniaturized SAW filter structure having different electrode layer thicknesses in accordance with the third embodiment of the present invention;
fig. 13 is a performance curve of a miniaturized saw filter structure with different insulating layer thicknesses in the third embodiment of the present invention;
FIG. 14 is a graph showing the performance of a miniaturized SAW filter structure having different piezoelectric film layer thicknesses in accordance with the third embodiment of the present invention;
Fig. 15 is an admittance curve of a miniaturized surface acoustic wave filter structure in the third embodiment of the present invention;
fig. 16 is a schematic structural diagram of a miniaturized surface acoustic wave filter structure and a schematic acoustic wave propagation interface in accordance with a fourth embodiment of the present invention;
FIG. 17 is a graph showing the performance of a miniaturized SAW filter structure having different electrode layer thicknesses in accordance with the fourth embodiment of the present invention;
fig. 18 is a graph showing performance curves of a miniaturized saw filter structure having different insulating layer thicknesses in accordance with the fourth embodiment of the present invention;
FIG. 19 is a graph showing the performance of a miniaturized SAW filter structure having different piezoelectric film layer thicknesses in accordance with the fourth embodiment of the present invention;
FIG. 20 is a graph showing the performance of a miniaturized SAW filter structure having different bottom temperature patch thicknesses in accordance with the fourth embodiment of the present invention;
fig. 21 is an admittance curve of a miniaturized surface acoustic wave filter structure in accordance with the fourth embodiment of the present invention;
fig. 22 is a schematic structural diagram of a miniaturized surface acoustic wave filter structure and a schematic acoustic wave propagation interface in a fifth embodiment of the present invention;
FIG. 23 is a graph showing the performance of a miniaturized SAW filter structure having different upper temperature patch thicknesses in accordance with the fifth embodiment of the present invention;
Fig. 24 is a performance curve of a miniaturized saw filter structure with different electrode layer thicknesses in a fifth embodiment of the present invention;
fig. 25 is a graph showing performance curves of a miniaturized saw filter structure having different insulating layer thicknesses in accordance with the fourth embodiment of the present invention;
FIG. 26 is a graph showing the performance of a miniaturized SAW filter structure having different piezoelectric film layer thicknesses in accordance with the fourth embodiment of the present invention;
fig. 27 is a performance curve of a miniaturized saw filter structure with different lower temperature patch thicknesses in accordance with the fourth embodiment of the present invention;
fig. 28 is an admittance curve of a miniaturized surface acoustic wave filter structure in accordance with the fourth embodiment of the present invention;
reference numerals illustrate: the piezoelectric substrate 1, the electrode layer 2, the insulating layer 3, the upper temperature compensation layer 4, the piezoelectric film layer 5 and the lower temperature compensation layer 6.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present invention more clear, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. It will be apparent that the described embodiments are some, but not all, embodiments of the invention. All other embodiments, which can be made by a person skilled in the art without creative efforts, based on the described embodiments of the present invention fall within the protection scope of the present invention. Unless defined otherwise, technical or scientific terms used herein should be given the ordinary meaning as understood by one of ordinary skill in the art to which this invention belongs.
The structure of the surface acoustic wave filter in the prior art as shown in fig. 1 includes an electrode layer 2 and a piezoelectric substrate 1, wherein the electrode layer 2 is directly laid on the surface of the piezoelectric substrate 1, at this time, the acoustic wave is partially incident into the piezoelectric substrate 1 in the propagation process, meanwhile, the contact surface x=0 of the electrode layer 2 and the piezoelectric substrate 1, at this time, the electrical displacement and stress boundary conditions of the contact interface of the electrode layer 2 and the piezoelectric substrate 1 are as follows:
normal electrical displacement continuous boundary condition: d (D) n (x + )-D n (x - )＝σ n (x)
Tangential electrical displacement continuous boundary condition: d (D) T (x + )＝D T (x - )＝0
Normal stress continuous boundary condition: t (T) n (x + )＝T n (x - )
Tangential stress continuous boundary condition: t (T) T (x + )＝T T (x - )
And the piezoelectric substrate of the surface acoustic wave filter with the traditional structure has a free interface, so:
T n (x + )＝T n (x - )＝0
T T (x + )＝T T (x - )＝0
therefore, for the piezoelectric substrate with the traditional structure, the excited acoustic wave mode is generally single, acoustic waves leak into the piezoelectric substrate, the high Q value cannot be realized, and meanwhile, the larger deformation generated by the expansion and contraction of the electrode layer has larger influence on the temperature sensitivity of the device, so that the characteristics of low temperature drift and the like cannot be realized. Meanwhile, the material of the piezoelectric substrate in the prior art is typically lithium tantalate (LiTaO 3 ) Lithium niobate (LiNbO) 3 ) And the like, the acoustic surface wave filter manufactured by adopting the structure and the materials is excited into a high sound velocity acoustic wave mode, and the sound velocity is generally between 3500m/s and 4500m/s, so that the miniaturization requirement of the SAW device can not be met.
Embodiment one:
in order to solve the above technical problems, the present invention provides a miniaturized saw filter structure, as shown in fig. 2, (a) is a schematic structural diagram of the saw filter structure, and (B) is a schematic acoustic wave propagation interface diagram of the saw filter structure, including a piezoelectric substrate 1 and an electrode layer 2, and further includes an insulating layer 3, where the insulating layer 3 is located between the piezoelectric substrate 1 and the electrode layer 2 and enables the piezoelectric substrate 1 and the electrode layer 2 to be completely separated, and the insulating layer 3 partially covers the surface of the piezoelectric substrate 1.
In the present embodiment, the axial width v of the insulating layer 3 is larger than the axial width w of the electrode layer 2. A first insulating layer 3 and a second insulating layer 3 are respectively arranged on the piezoelectric substrate 1 along the axial direction, the axial distance between the first insulating layer 3 and the second insulating layer 3 is larger than 0, a first electrode layer 2 is arranged on the first insulating layer 3, and a second electrode layer 2 is arranged on the second insulating layer 3. The first electrode layer 2 is arranged at the middle position of the first insulating layer 3, and the second electrode layer 2 is arranged at the middle position of the second insulating layer 3.
In the present embodiment, the axial width dimension of the first insulating layer 3 is v1, the axial width dimension of the second insulating layer 3 is v2, the axial width dimension of the first electrode layer 2 is w1, the axial width dimension of the second electrode layer 2 is w2, and the following is satisfied:
w1≤v1≤0.5λ
w2≤v2≤0.5λ
Wherein: lambda is the wavelength corresponding to the electrode layer 2.
In the present embodiment, the axial width dimension v1=0.3λ of the first insulating layer 3, the axial width dimension v2=0.35λ of the second insulating layer 3, the axial width dimension w1=0.25λ of the first electrode layer 2, and the axial width dimension w2=0.25λ of the second electrode layer 2.
In the present embodiment, the surface x of the piezoelectric substrate 1 in contact with the insulating layer 3 1 The electrical and mechanical boundary conditions (as in regions B, d in fig. 2 (B):
the normal electric displacement continuous boundary conditions are: d (D) n (x 1 + )-D n (x 1 - )＝0
The tangential electrical displacement continuous boundary conditions are: d (D) T (x 1 + )＝D T (x 1 - )≠0
The normal stress continuous boundary conditions are: t (T) n (x 1 + )＝T n (x 1 - )≠0
The tangential stress continuous boundary conditions are: t (T) T (x 1 + )＝T T (x 1 - )≠0
Wherein: x is x 1 + Is x 1 X is the upper surface of (x) 1 — Is x 1 Lower surface of D n For normal electric displacement, D T For tangential electrical displacement, T n Is normal stress, T T Is tangential stress;
surface x of piezoelectric substrate 1 not in contact with insulating layer 3 1 The electrical and mechanical boundary conditions (as in regions a, c, e in FIG. 2 (B):
the normal electric displacement continuous boundary conditions are: d (D) n (x 1 + )-D n (x 1 - )＝σ n (x 1 )
The tangential electrical displacement continuous boundary conditions are: d (D) T (x 1 + )＝D T (x 1 - )＝0
The normal stress continuous boundary conditions are: t (T) n (x 1 + )＝T n (x 1 - )＝0
The tangential stress continuous boundary conditions are: t (T) T (x 1 + )＝T T (x 1 - )＝0
The contact surface x of the insulating layer 3 with the electrode layer 2 2 Electrical and mechanical boundary conditions of (a):
The normal electric displacement continuous boundary conditions are: d (D) n (x 2 + )-D n (x 2 - )＝σ n (x 2 )
The tangential electrical displacement continuous boundary conditions are: d (D) T (x 2 + )＝D T (x 2 - )＝0
The normal stress continuous boundary conditions are: t (T) n (x 2 + )＝T n (x 2 - )＝0
The tangential stress continuous boundary conditions are: t (T) T (x 2 + )＝T T (x 2 - )＝0
Wherein: x is x 2 + Is x 2 X is the upper surface of (x) 2 — Is x 2 Lower surface of sigma n Is a charge;
then use x 1 And x 2 The interface stress continuous boundary condition and the electric displacement continuous boundary condition are used for establishing an eigenvalue of the surface acoustic wave filter structure based on the heterogeneous integrated structure, and the eigenvalue is as follows:
wherein, at the insulating layer: e=0;
wherein: c is the elastic constant of the material, e is the piezoelectric stress constant, epsilon is the dielectric constant, rho is the density, and u is the displacement.
In this embodiment, the thickness h1 of the electrode layer 2 is in the range of 0.01λ -1λ (as shown in fig. 3, which is a performance curve of different electrode layer thicknesses, where (a) is the phase velocity Vp and the amplitude difference |yr-ya|, (b) is the resonance frequency fr, the antiresonance frequency fa, and the bandwidth delta_f, and (c) is the electromechanical coupling coefficient K) 2 Relative bandwidth BW; (d) The Bold Q value), the thickness h3 of the piezoelectric substrate 1 ranges from 0.01λ to 500λ. The thickness of the electrode layer 2 was 0.05λ, the width w1=w2=0.25λ, and the thickness of the piezoelectric substrate 1 was 0.25mm.
In this embodiment, the electrode layer 2 is an interdigital electrode located on the surface of the material of the insulating layer 3, and is made of at least one of the following materials: aluminum Al, copper Cu, gold Au, platinum Pt and copper aluminum alloy. The piezoelectric substrate 1 is made of at least one of the following materials: lithium niobate LiNbO 3 Lithium tantalate LiTaO 3 Quartz, lithium tetraborate, lanthanum gallium silicate, lanthanum gallium niobate. In the present embodiment, the electrode layer 2 is made of Cu, and the piezoelectric substrate is made of LiNbO 3 Is prepared.
In the present embodiment, the insulating layer 3 is made of at least one of the following materials: silicon dioxide SiO 2 Sapphire and silicon nitride Si 3 N 4 . In particular, insulationLayer 3 is silicon dioxide SiO 2 Is prepared.
In this embodiment, the thickness h2 of the insulating layer 3 is 0.001 λ -1λ, the width v1=0.3λ, and the width v2=0.35λ, where λ is the wavelength corresponding to the electrode layer 2. As shown in fig. 4, the performance curves of different insulating layers 3 are shown, wherein (a) is the phase velocity Vp and the amplitude difference |yr-ya|, (b) is the resonance frequency fr, the antiresonance frequency fa and the bandwidth delta_f; (c) For the electromechanical coupling coefficient K 2 Relative bandwidth BW; (d) is the Bold_Q value. The thickness of the specific insulating layer 3 was 0.014λ.
As shown in fig. 5, the admittance curve of the saw filter structure in this embodiment can be shown, according to the admittance curve, the design of the insulating layer 3 can effectively realize the excitation of the main mode acoustic wave.
Embodiment two: in this embodiment, (a) is a schematic structural diagram of a surface acoustic wave filter structure, and (B) is a schematic acoustic wave propagation interface diagram of the surface acoustic wave filter structure, and further includes an upper temperature compensation layer made of a material having a positive temperature coefficient, wherein the temperature compensation layer is located on a surface of a piezoelectric substrate, and the upper temperature compensation layer completely covers the insulating layer and the electrode layer, as shown in fig. 6.
In this embodiment, the surface x of the piezoelectric substrate in contact with the insulating layer 1 The electrical and mechanical boundary conditions (as in regions B, d in fig. 6 (B):
the normal electric displacement continuous boundary conditions are: d (D) n (x 1 + )-D n (x 1 - )＝0
The tangential electrical displacement continuous boundary conditions are: d (D) T (x 1 + )＝D T (x 1 - )≠0
The normal stress continuous boundary conditions are: t (T) n (x 1 + )＝T n (x 1 - )≠0
The tangential stress continuous boundary conditions are: t (T) T (x 1 + )＝T T (x 1 - )≠0
A surface x of the piezoelectric substrate which is not contacted with the insulating layer 1 The electrical and mechanical boundary conditions (as in regions a, c, e in fig. 6 (B):
the normal electric displacement continuous boundary conditions are: d (D) n (x 1 + )-D n (x 1 - )＝σ n (x 1 )
The tangential electrical displacement continuous boundary conditions are: d (D) T (x 1 + )＝D T (x 1 - )＝0
The normal stress continuous boundary conditions are: t (T) n (x 1 + )＝T n (x 1 - )＝0
The tangential stress continuous boundary conditions are: t (T) T (x 1 + )＝T T (x 1 - )＝0
Wherein: sigma (sigma) n Is a charge;
the contact surface x of the insulating layer and the electrode layer 2 Electrical and mechanical boundary conditions of (a):
the normal electric displacement continuous boundary conditions are: d (D) n (x 2 + )-D n (x 2 - )＝σ n (x 2 )
The tangential electrical displacement continuous boundary conditions are: d (D) T (x 2 + )＝D T (x 2 - )＝0
The normal stress continuous boundary conditions are: t (T) n (x 2 + )＝T n (x 2 - )＝0
The tangential stress continuous boundary conditions are: t (T) T (x 2 + )＝T T (x 2 - )＝0
The temperature compensation principle of the upper temperature compensation layer is as follows:
ρ θ ＝ρ+ρ (1) θ+ρ (2) θ 2 +ρ (3) θ 3
r θ ＝r+r (1) θ+r (2) θ 2 +r (3) θ 3
g θ ＝g+g (1) θ+g (2) θ 2 +g (3) θ 3
θ＝(T-T 0 )
wherein, the liquid crystal display device comprises a liquid crystal display device,
is an n-order coefficient of elastic constant, +.>
Is an n-order coefficient of the piezoelectric stress constant, +.>
N-order coefficient of dielectric constant, delta ik Is the Kronecker operator, +.>
For the n-order thermal expansion temperature coefficient ρ (n) Is the n-order coefficient of density, r (n) N-order coefficient g of first Ramez constant of electrode layer (n) N-order coefficient, T, of the second Lame constant of the electrode layer 0 Is the reference temperature, T is the temperature environment, and θ is the temperature difference.
Then use x 1 And x 2 The interface stress continuous boundary condition and the electric displacement continuous boundary condition are used for establishing an eigenvalue of the surface acoustic wave filter structure based on the heterogeneous integrated structure, and the eigenvalue is as follows:
wherein, at insulating layer and piezoelectricity substrate: eθ=0;
wherein: c (C) θ E is the elastic constant of the material changing with temperature θ Epsilon as the piezoelectric stress constant with temperature θ For a dielectric constant as a function of temperature ρ θ For density as a function of temperature, u is displacement.
In the present embodiment, the thickness h1 of the upper temperature compensation layer ranges from 0.01λ to 5λ (as shown in fig. 7, wherein (a) is the phase velocity Vp and the amplitude difference |yr-ya|, (b) is the resonance frequency fr, the antiresonance frequency fa and the bandwidth delta_f, and (c) is the electromechanical coupling coefficient K) 2 Relative bandwidth BW; (d) is the Bold_Q value). The upper temperature compensation layer adopts silicon dioxide SiO 2 The material is made of a thickness of 0.46 lambda.
In the present embodiment, the thickness h2 of the electrode layer 2 has a value ranging from 0.01λ to 1λ (as shown in fig. 8, which is a performance curve of different electrode layer thicknesses, wherein (a) is a phase velocity Vp and a magnitude difference |yr-ya|, (b) is a resonance frequency fr, an antiresonance frequency fa, and a bandwidth delta_f, and (c) is an electromechanical coupling coefficient K 2 Relative bandwidth BW; (d) The Bold Q value), the thickness h3 of the piezoelectric substrate 1 ranges from 0.01λ to 500λ. The thickness of the electrode layer 2 was 0.122 λ, the width w1=w2=0.25λ, and the thickness of the piezoelectric substrate 1 was 0.25mm.
In this embodiment, the thickness h3 of the insulating layer 3 is 0.001 λ -1λ, the width v1=0.3λ, and the width v2=0.35λ, where λ is the wavelength corresponding to the electrode layer 2. Fig. 9 shows performance curves for different insulating layer 3 thicknesses, where (a) is phase velocity Vp and amplitude difference |yr-ya|, (b) is resonant frequency fr, antiresonant frequency fa, and bandwidth delta_f; (c) For the electromechanical coupling coefficient K 2 Relative bandwidth BW; (d) is the Bold_Q value.
As shown in fig. 10, the admittance curve of the saw filter structure in this embodiment can be shown, according to the admittance curve, the design of the insulating layer 3 can effectively realize the excitation of the main mode acoustic wave.
Embodiment III: in this embodiment, (a) is a schematic structural diagram of a surface acoustic wave filter structure, and (B) is a schematic acoustic wave propagation interface diagram of a surface acoustic wave filter structure, and further includes a piezoelectric thin film layer, the piezoelectric thin film layer is located between the piezoelectric substrate and the insulating layer, the piezoelectric thin film layer completely covers the surface of the piezoelectric substrate, and the insulating layer partially covers the surface of the piezoelectric thin film layer, as shown in fig. 11.
In the present embodiment, the surface x of the piezoelectric thin film layer in contact with the insulating layer 1 (B, d region in FIG. 11 (B)) in the electrical and mechanical boundary conditions:
the normal electric displacement continuous boundary conditions are: d (D) n (x 1 + )-D n (x 1 - )＝0
The tangential electrical displacement continuous boundary conditions are: d (D) T (x 1 + )＝D T (x 1 - )≠0
The normal stress continuous boundary conditions are: t (T) n (x 1 + )＝T n (x 1 - )≠0
The tangential stress continuous boundary conditions are: t (T) T (x 1 + )＝T T (x 1 - )≠0
A surface x of the piezoelectric thin film layer which is not contacted with the insulating layer 1 The electrical and mechanical boundary conditions of (regions a, c, e in fig. 11 (B):
the normal electric displacement continuous boundary conditions are: d (D) n (x 1 + )-D n (x 1 - )＝σ n (x 1 )
The tangential electrical displacement continuous boundary conditions are: d (D) T (x 1 + )＝D T (x 1 - )＝0
The normal stress continuous boundary conditions are: t (T) n (x 1 + )＝T n (x 1 - )＝0
The tangential stress continuous boundary conditions are: t (T) T (x 1 + )＝T T (x 1 - )＝0
The contact surface x of the insulating layer and the electrode layer 2 Electrical and mechanical boundary conditions of (a):
the normal electric displacement continuous boundary conditions are: d (D) n (x 2 + )-D n (x 2 - )＝ρ n (x 2 )
The tangential electrical displacement continuous boundary conditions are: d (D) T (x 2 + )＝D T (x 2 - )＝0
The normal stress continuous boundary conditions are: t (T) n (x 2 + )＝T n (x 2 - )＝0
The tangential stress continuous boundary conditions are: t (T) T (x 2 + )＝T T (x 2 - )＝0
The contact surface x of the piezoelectric film layer and the piezoelectric substrate 3 Electrical and mechanical boundary conditions of (a):
the normal electric displacement continuous boundary conditions are: d (D) n (x 3 + )-D n (x 3 - )＝0
The tangential electrical displacement continuous boundary conditions are: d (D) T (x 3 + )＝D T (x 3 - )≠0
The normal stress continuous boundary conditions are: t (T) n (x 3 + )＝T n (x 3 - )≠0
The tangential stress continuous boundary conditions are: t (T) T (x 3 + )＝T T (x 3 - )≠0
Then use x 1 、x 2 、x 3 The interface stress continuous boundary condition and the electric displacement continuous boundary condition are used for establishing an eigenvalue of the surface acoustic wave filter structure based on the heterogeneous integrated structure, and the eigenvalue is as follows:
wherein, at the insulating layer: e=0
Wherein: c is the elastic constant of the material, e is the piezoelectric stress constant, epsilon is the dielectric constant, rho is the density, and u is the displacement.
In the present embodiment, the thickness h1 of the electrode layer 2 has a value ranging from 0.01λ to 1λ (as shown in fig. 12, which is a performance curve of different electrode layer thicknesses, wherein (a) is a phase velocity Vp and a magnitude difference |yr-ya|, (b) is a resonance frequency fr, an antiresonance frequency fa, and a bandwidth delta_f, and (c) is an electromechanical coupling coefficient K 2 Relative bandwidth BW; (d) The Bold Q value), the thickness h3 of the piezoelectric substrate 1 ranges from 0.01λ to 500λ. The thickness of the electrode layer 2 was 0.10λ, the width w1=w2=0.25λ, and the thickness of the piezoelectric substrate 1 was 0.35mm, and silicon carbide was used as the piezoelectric substrate.
In this embodiment, the insulating layer is made of a sapphire material, and the thickness h2 of the insulating layer 3 is 0.001 λ -1λ, the width v1=0.3λ, and the width v2=0.35λ, where λ is a wavelength corresponding to the electrode layer 2. Fig. 13 shows performance curves for different insulating layer 3 thicknesses, wherein (a) is phase velocity Vp and amplitude difference |yr-ya|, (b) is resonant frequency fr, antiresonant frequency fa, and bandwidth delta_f; (c) For the electromechanical coupling coefficient K 2 Relative bandwidth BW; (d) is the Bold_Q value.
In this embodiment, the piezoelectric film layer is made of at least one of the following materials: lithium niobate LiNbO 3 Lithium tantalate LiTaO 3 Quartz Quartz, lithium tetraborate, lanthanum gallium silicate, lanthanum gallium niobate layers, in this particular embodiment, the piezoelectric thin film layer is lithium niobate LiNbO 3 The thickness h3 of the piezoelectric film layer is 0.01λ -500λ, where λ is the wavelength corresponding to the electrode layer 2. FIG. 14 shows performance curves for different piezoelectric film thicknesses, wherein (a) is phase velocity Vp and amplitude difference |Yr-ya|, (b) is resonant frequency fr, antiresonant frequencyRate fa and bandwidth Delta f; (c) For the electromechanical coupling coefficient K 2 Relative bandwidth BW; (d) is the Bold_Q value.
As shown in fig. 15, the admittance curve of the saw filter structure in this embodiment can be shown, according to the admittance curve, the design of the insulating layer 3 can effectively realize the excitation of the main mode acoustic wave.
Embodiment four: the difference from the first embodiment is that, in this embodiment, as shown in fig. 16, (a) is a schematic structural diagram of a surface acoustic wave filter structure, and (B) is a schematic acoustic wave propagation interface diagram of the surface acoustic wave filter structure, and further includes a lower temperature compensation layer, where the lower temperature compensation layer is located between the piezoelectric substrate and the piezoelectric thin film layer, the lower temperature compensation layer is made of a material with a positive temperature coefficient, and the lower temperature compensation layer completely covers the surface of the piezoelectric substrate, and the piezoelectric thin film layer completely covers the surface of the lower temperature compensation layer.
In the present embodiment, the surface x of the piezoelectric thin film layer in contact with the insulating layer 1 (in the electrical and mechanical boundary conditions of B, d) in FIG. 16 (B):
the normal electric displacement continuous boundary conditions are: d (D) n (x 1 + )-D n (x 1 - )＝0
The tangential electrical displacement continuous boundary conditions are: d (D) T (x 1 + )＝D T (x 1 - )≠0
The normal stress continuous boundary conditions are: t (T) n (x 1 + )＝T n (x 1 - )≠0
The tangential stress continuous boundary conditions are: t (T) T (x 1 + )＝T T (x 1 - )≠0
A surface x of the piezoelectric thin film layer which is not contacted with the insulating layer 1 (in the electrical and mechanical boundary conditions of a, c, e) in FIG. 16 (B):
the normal electric displacement continuous boundary conditions are: d (D) n (x 1 + )-D n (x 1 - )＝σ n (x 1 )
The tangential electrical displacement continuous boundary conditions are: d (D) T (x 1 + )＝D T (x 1 - )＝0
The normal stress continuous boundary conditions are: t (T) n (x 1 + )＝T n (x 1 - )＝0
The tangential stress continuous boundary conditions are: t (T) T (x 1 + )＝T T (x 1 - )＝0
The contact surface x of the insulating layer and the electrode layer 2 Electrical and mechanical boundary conditions of (a):
the normal electric displacement continuous boundary conditions are: d (D) n (x 2 + )-D n (x 2 - )＝σ n (x 2 )
The tangential electrical displacement continuous boundary conditions are: d (D) T (x 2 + )＝D T (x 2 - )＝0
The normal stress continuous boundary conditions are: t (T) n (x 2 + )＝T n (x 2 - )＝0
The tangential stress continuous boundary conditions are: t (T) T (x 2 + )＝T T (x 2 - )＝0
The contact surface x of the piezoelectric film layer and the lower temperature compensation layer 3 Electrical and mechanical boundary conditions of (a):
the normal electric displacement continuous boundary conditions are: d (D) n (x 3 + )-D n (x 3 - )＝0
The tangential electrical displacement continuous boundary conditions are: d (D) T (x 3 + )＝D T (x 3 - )≠0
The normal stress continuous boundary conditions are: t (T) n (x 3 + )＝T n (x 3 - )≠0
The tangential stress continuous boundary conditions are: t (T) T (x 3 + )＝T T (x 3 - )≠0
The contact surface x of the lower temperature compensation layer and the piezoelectric substrate 4 Electrical and mechanical boundary conditions of (a):
the normal electric displacement continuous boundary conditions are: d (D) n (x 4 + )-D n (x 4 - )＝0
The tangential electrical displacement continuous boundary conditions are: d (D) T (x 4 + )＝D T (x 4 - )≠0
The normal stress continuous boundary conditions are: t (T) n (x 4 + )＝T n (x 4 - )≠0
The tangential stress continuous boundary conditions are: t (T) T (x 4 + )＝T T (x 4 - )≠0
The temperature compensation principle of the lower temperature compensation layer is as follows:
ρ θ ＝ρ+ρ (1) θ+ρ (2) θ 2 +ρ (3) θ 3
r θ ＝r+r (1) θ+r (2) θ 2 +r (3) θ 3
g θ ＝g+g (1) θ+g (2) θ 2 +g (3) θ 3
θ＝(T-T 0 )
wherein, the liquid crystal display device comprises a liquid crystal display device,
is an n-order coefficient of elastic constant, +.>
Is an n-order coefficient of the piezoelectric stress constant, +.>
N-order coefficient of dielectric constant, delta ik Is the Kronecker operator, +.>
For the n-order thermal expansion temperature coefficient ρ (n) Is the n-order coefficient of density, r (n) N-order coefficient g of first Ramez constant of electrode layer (n) N-order coefficient, T, of the second Lame constant of the electrode layer 0 Is the reference temperature, T is the temperature environment, and θ is the temperature difference.
Then use x 1 、x 2 、x 3 And x 4 The interface stress continuous boundary condition and the electric displacement continuous boundary condition are used for establishing an eigenvalue of the surface acoustic wave filter structure based on the heterogeneous integrated structure, and the eigenvalue is as follows:
wherein, at insulating layer and piezoelectricity substrate: eθ=0
Wherein: c (C) θ E is the elastic constant of the material changing with temperature θ Epsilon as the piezoelectric stress constant with temperature θ For a dielectric constant as a function of temperature ρ θ For density as a function of temperature, u is displacement.
In the present embodiment, the thickness h1 of the electrode layer 2 ranges from 0.01λ to 1λ (as shown in FIG. 17, which shows the performance curves at different electrode layer thicknessesWherein (a) is the phase velocity Vp and the amplitude difference |yr-ya|, (b) is the resonance frequency fr, the antiresonance frequency fa and the bandwidth delta_f; (c) For the electromechanical coupling coefficient K 2 Relative bandwidth BW; (d) The Bold Q value), the thickness h5 of the piezoelectric substrate 1 ranges from 0.01λ to 500λ.
In this embodiment, the material of the electrode layer 2 is aluminum, the thickness of the electrode layer 2 is 0.05λ, the width w1=w2=0.25λ, the thickness of the piezoelectric substrate 1 is 0.35mm, and the piezoelectric substrate is a silicon carbide substrate.
In this embodiment, the insulating layer is made of a sapphire material, and the thickness h2 of the insulating layer 3 is 0.001 λ -1λ, specifically 0.014λ, the width v1=0.3λ, and the width v2=0.35λ, where λ is the wavelength corresponding to the electrode layer 2. Fig. 18 shows performance curves for different insulating layer 3 thicknesses, wherein (a) is phase velocity Vp and amplitude difference |yr-ya|, (b) is resonant frequency fr, antiresonant frequency fa, and bandwidth delta_f; (c) For the electromechanical coupling coefficient K 2 Relative bandwidth BW; (d) is the Bold_Q value.
In this embodiment, the piezoelectric film layer is made of at least one of the following materials: lithium niobate LiNbO 3 Lithium tantalate LiTaO 3 Quartz Quartz, lithium tetraborate, lanthanum gallium silicate, lanthanum gallium niobate layers, in this particular embodiment, the piezoelectric thin film layer is lithium niobate LiNbO 3 The thickness h3 of the piezoelectric film layer is 0.01λ -500λ, specifically, the thickness of the piezoelectric film layer is 0.2λ, where λ is the wavelength corresponding to the electrode layer 2. FIG. 19 shows performance curves for different piezoelectric film thicknesses, wherein (a) is phase velocity Vp and amplitude difference |Yr-ya|, (b) is resonant frequency fr, antiresonant frequency fa, and bandwidth Delta_f; (c) For the electromechanical coupling coefficient K 2 Relative bandwidth BW; (d) is the Bold_Q value.
In the present embodiment, the thickness h4 of the lower temperature compensation layer ranges from 0.01λ to 2λ (as shown in fig. 20, wherein (a) is the phase velocity Vp and the amplitude difference |yr-ya|, (b) is the resonance frequency fr, the antiresonance frequency fa and the bandwidth delta_f, and (c) is the electromechanical coupling coefficient K) 2 Relative bandwidth BW; (d) For the Bold_Q value), the lower temperature compensation layer adopts sapphire Al 2 O 3 The material is made of a thickness of 0.3λ.
As shown in fig. 21, the admittance curve of the saw filter structure in this embodiment can be shown, according to the admittance curve, the design of the insulating layer 3 can effectively realize the excitation of the main mode acoustic wave.
Fifth embodiment: the difference from the fourth embodiment is that, in this embodiment, as shown in fig. 22, (a) is a schematic structural diagram of a surface acoustic wave filter structure, and (B) is a schematic acoustic wave propagation interface diagram of the surface acoustic wave filter structure, in this embodiment, an upper temperature compensation layer is further included, and is made of a material having a positive temperature coefficient, the upper temperature compensation layer is located on the surface of the piezoelectric film layer, and the upper temperature compensation layer completely covers the insulating layer and the electrode layer.
In the present embodiment, the thickness h1 of the upper temperature compensation layer ranges from 0.01λ to 5λ (as shown in fig. 23, wherein (a) is the phase velocity Vp and the amplitude difference |yr-ya|, (b) is the resonance frequency fr, the antiresonance frequency fa and the bandwidth delta_f, and (c) is the electromechanical coupling coefficient K) 2 Relative bandwidth BW; (d) is the Bold_Q value). The upper temperature compensation layer adopts silicon dioxide SiO 2 The material is made of a thickness of 0.45 lambda.
In the present embodiment, the thickness h2 of the electrode layer 2 has a value ranging from 0.01λ to 1λ (as shown in fig. 24, which is a performance curve of different electrode layer thicknesses, wherein (a) is a phase velocity Vp and a magnitude difference |yr-ya|, (b) is a resonance frequency fr, an antiresonance frequency fa, and a bandwidth delta_f, and (c) is an electromechanical coupling coefficient K 2 Relative bandwidth BW; (d) The Bold Q value), the thickness h6 of the piezoelectric substrate 1 ranges from 0.01λ to 500λ.
In this embodiment, the thickness of the electrode layer 2 is 0.06λ, the width w1=w2=0.25λ, the thickness of the piezoelectric substrate 1 is 0.35mm, and the piezoelectric substrate is a silicon carbide substrate.
In this embodiment, the insulating layer is made of sapphire material, the thickness h3 of the insulating layer 3 is 0.001-1λ, the width v1=0.3λ, the width v2=0.35λ, where λ is the electrode layer2, the corresponding wavelength. Fig. 25 shows performance curves for different insulating layer 3 thicknesses, wherein (a) is phase velocity Vp and amplitude difference |yr-ya|, (b) is resonant frequency fr, antiresonant frequency fa, and bandwidth delta_f; (c) For the electromechanical coupling coefficient K 2 Relative bandwidth BW; (d) is the Bold_Q value.
In this embodiment, the piezoelectric film layer is made of at least one of the following materials: lithium niobate LiNbO 3 Lithium tantalate LiTaO 3 Quartz Quartz, lithium tetraborate, lanthanum gallium silicate, lanthanum gallium niobate layers, in this particular embodiment, the piezoelectric thin film layer is lithium niobate LiNbO 3 The thickness h4 of the piezoelectric film layer is 0.01λ -500λ, where λ is the wavelength corresponding to the electrode layer 2. FIG. 26 shows performance curves for different piezoelectric film thicknesses, wherein (a) is phase velocity Vp and amplitude difference |Yr-ya|, (b) is resonant frequency fr, antiresonant frequency fa and bandwidth Delta_f; (c) For the electromechanical coupling coefficient K 2 Relative bandwidth BW; (d) is the Bold_Q value.
In this embodiment, the thickness h5 of the lower temperature compensation layer ranges from 0.01λ to 2λ (as shown in FIG. 27, which shows performance curves for different lower temperature compensation layers 2 The material is made of a thickness of 0.3λ.
As shown in fig. 28, the admittance curve of the saw filter structure in this embodiment can be shown, according to the admittance curve, the design of the insulating layer 3 can effectively realize the excitation of the main mode acoustic wave.
Finally, it should be noted that the above embodiments are only for illustrating the technical solution of the present invention and not for limiting the technical solution, and those skilled in the art should understand that modifications and equivalents may be made to the technical solution of the present invention without departing from the spirit and scope of the present invention, and all such modifications and equivalents are included in the scope of the claims.
Claims (10)
1. A miniaturized surface acoustic wave filter structure comprising a piezoelectric substrate and an electrode layer, characterized by further comprising an insulating layer having a galvanic isolation capability, the insulating layer being located between the piezoelectric substrate and the electrode layer and completely separating the piezoelectric substrate and the electrode layer, and the insulating layer partially covering the surface of the piezoelectric substrate.
2. The miniaturized surface acoustic wave filter structure according to claim 1, wherein a first insulating layer and a second insulating layer are provided on the piezoelectric substrate in an axial direction, respectively, an axial distance between the first insulating layer and the second insulating layer is greater than 0, and a first electrode layer is provided on the first insulating layer, a width of the first insulating layer is greater than a width of the first electrode layer, and a second electrode layer is provided on the second insulating layer, a width of the second insulating layer is greater than a width of the second electrode layer.
3. The miniaturized surface acoustic wave filter structure of claim 1 wherein the surface x of the piezoelectric substrate in contact with the insulating layer 1 Electrical and mechanical boundary conditions of (a):
the normal electric displacement continuous boundary conditions are:
D n (x 1 + )-D n (x 1 - )＝0
the tangential electrical displacement continuous boundary conditions are:
D T (x 1 + )＝D T (x 1 - )≠0
the normal stress continuous boundary conditions are:
T n (x 1 + )＝T n (x 1 - )≠0
the tangential stress continuous boundary conditions are:
T T (x 1 + )＝T T (x 1 - )≠0
wherein: x is x 1 + Is x 1 X is the upper surface of (x) 1 — Is x 1 Lower surface of D n For normal electric displacement, D T For cuttingTo electric displacement, T n Is normal stress, T T Is tangential stress;
a surface x of the piezoelectric substrate which is not contacted with the insulating layer 1 Electrical and mechanical boundary conditions of (a):
the normal electric displacement continuous boundary conditions are:
D n (x 1 + )-D n (x 1 - )＝σ n (x 1 )
the tangential electrical displacement continuous boundary conditions are:
D T (x 1 + )＝D T (x 1 - )＝0
the normal stress continuous boundary conditions are:
T n (x 1 + )＝T n (x 1 - )＝0
the tangential stress continuous boundary conditions are:
T T (x 1 + )＝T T (x 1 - )＝0
wherein: sigma (sigma) n Is a charge;
the contact surface x of the insulating layer and the electrode layer 2 Electrical and mechanical boundary conditions of (a):
the normal electric displacement continuous boundary conditions are:
D n (x 2 + )-D n (x 2 - )＝σ n (x 2 )
the tangential electrical displacement continuous boundary conditions are:
D T (x 2 + )＝D T (x 2 - )＝0
the normal stress continuous boundary conditions are:
T n (x 2 + )＝T n (x 2 - )＝0
the tangential stress continuous boundary conditions are:
T T (x 2 + )＝T T (x 2 - )＝0
wherein: x is x 2 + Is x 2 X is the upper surface of (x) 2 — Is x 2 Lower surface of sigma n Is a charge;
then use x 1 And x 2 The interface stress continuous boundary condition and the electric displacement continuous boundary condition are used for establishing an eigenvalue of the surface acoustic wave filter structure based on the heterogeneous integrated structure, and the eigenvalue is as follows:
wherein, at the insulating layer:
e＝0
wherein: c is the elastic constant of the material, e is the piezoelectric stress constant, epsilon is the dielectric constant, rho is the density, and u is the displacement.
4. The miniaturized surface acoustic wave filter structure of claim 1 further comprising an upper temperature patch layer, wherein the upper temperature patch layer is made of a material having a positive temperature coefficient, wherein the temperature patch layer is located over a surface of the piezoelectric substrate, and wherein the upper temperature patch layer completely covers the insulating layer and the electrode layer.
5. The miniaturized surface acoustic wave filter structure of claim 4 wherein the surface x of the piezoelectric substrate in contact with the insulating layer 1 Electrical and mechanical boundary conditions of (a):
the normal electric displacement continuous boundary conditions are:
D n (x 1 + )-D n (x 1 - )＝0
the tangential electrical displacement continuous boundary conditions are:
D T (x 1 + )＝D T (x 1 - )≠0
the normal stress continuous boundary conditions are:
T n (x 1 + )＝T n (x 1 - )≠0
the tangential stress continuous boundary conditions are:
T T (x 1 + )＝T T (x 1 - )≠0
wherein: x is x 1 + Is x 1 X is the upper surface of (x) 1 — Is x 1 Lower surface of D n For normal electric displacement, D T For tangential electrical displacement, T n Is normal stress, T T Is tangential stress;
a surface x of the piezoelectric substrate which is not contacted with the insulating layer 1 Electrical and mechanical boundary conditions of (a):
the normal electric displacement continuous boundary conditions are:
D n (x 1 + )-D n (x 1 - )＝σ n (x 1 )
the tangential electrical displacement continuous boundary conditions are:
D T (x 1 + )＝D T (x 1 - )＝0
the normal stress continuous boundary conditions are:
T n (x 1 + )＝T n (x 1 - )＝0
the tangential stress continuous boundary conditions are:
T T (x 1 + )＝T T (x 1 - )＝0
wherein: sigma (sigma) n Is a charge;
the contact surface x of the insulating layer and the electrode layer 2 Electrical and mechanical boundary conditions of (a):
the normal electric displacement continuous boundary conditions are:
D n (x 2 + )-D n (x 2 - )＝σ n (x 2 )
the tangential electrical displacement continuous boundary conditions are:
D T (x 2 + )＝D T (x 2 - )＝0
the normal stress continuous boundary conditions are:
T n (x 2 + )＝T n (x 2 - )＝0
the tangential stress continuous boundary conditions are:
T T (x 2 + )＝T T (x 2 - )＝0
wherein: x is x 2 + Is x 2 X is the upper surface of (x) 2 — Is x 2 Lower surface of sigma n Is a charge;
the temperature compensation principle of the upper temperature compensation layer is as follows:
ρ θ ＝ρ+ρ (1) θ+ρ (2) θ 2 +ρ (3) θ 3
r θ ＝r+r (1) θ+r (2) θ 2 +r (3) θ 3
g θ ＝g+g (1) θ+g (2) θ 2 +g (3) θ 3
θ＝(T-T 0 )
wherein, the liquid crystal display device comprises a liquid crystal display device,
is an n-order coefficient of elastic constant, +.>
Is an n-order coefficient of the piezoelectric stress constant, +.>
N-order coefficient of dielectric constant, delta ik Is the Kronecker operator, +.>
For the n-order thermal expansion temperature coefficient ρ (n) Is the n-order coefficient of density, r (n) N-order coefficient g of first Ramez constant of electrode layer (n) N-order coefficient, T, of the second Lame constant of the electrode layer 0 Is the reference temperature, T is the temperature environment, and θ is the temperature difference.
Then use x 1 And x 2 The interface stress continuous boundary condition and the electric displacement continuous boundary condition are used for establishing an eigenvalue of the surface acoustic wave filter structure based on the heterogeneous integrated structure, and the eigenvalue is as follows:
wherein, at insulating layer and piezoelectricity substrate:
eθ＝0
wherein: c (C) θ E is the elastic constant of the material changing with temperature θ Epsilon as the piezoelectric stress constant with temperature θ For a dielectric constant as a function of temperature ρ θ As a function of temperatureThe density of the change, u, is the displacement.
6. The miniaturized saw filter structure of claim 1, further comprising a piezoelectric thin film layer between the piezoelectric substrate and the insulating layer, the piezoelectric thin film layer completely covering the piezoelectric substrate surface, the insulating layer partially covering the piezoelectric thin film layer surface.
7. The miniaturized surface acoustic wave filter structure of claim 6 wherein the surface x of the piezoelectric thin film layer in contact with the insulating layer 1 Electrical and mechanical boundary conditions of (a):
the normal electric displacement continuous boundary conditions are:
D n (x 1 + )-D n (x 1 - )＝0
the tangential electrical displacement continuous boundary conditions are:
D T (x 1 + )＝D T (x 1 - )≠0
the normal stress continuous boundary conditions are:
T n (x 1 + )＝T n (x 1 - )≠0
the tangential stress continuous boundary conditions are:
T T (x 1 + )＝T T (x 1 - )≠0
wherein: x is x 1 + Is x 1 X is the upper surface of (x) 1 — Is x 1 Lower surface of D n For normal electric displacement, D T For tangential electrical displacement, T n Is normal stress, T T Is tangential stress;
a surface x of the piezoelectric thin film layer which is not contacted with the insulating layer 1 Electrical and mechanical boundary conditions of (a):
the normal electric displacement continuous boundary conditions are:
D n (x 1 + )-D n (x 1 - )＝σ n (x 1 )
the tangential electrical displacement continuous boundary conditions are:
D T (x 1 + )＝D T (x 1 - )＝0
the normal stress continuous boundary conditions are:
T n (x 1 + )＝T n (x 1 - )＝0
the tangential stress continuous boundary conditions are:
T T (x 1 + )＝T T (x 1 - )＝0
wherein: x is x 1 + Is x 1 X is the upper surface of (x) 1 — Is x 1 Is formed on the lower surface of the base plate;
the contact surface x of the insulating layer and the electrode layer 2 Electrical and mechanical boundary conditions of (a):
the normal electric displacement continuous boundary conditions are:
D n (x 2 + )-D n (x 2 - )＝σ n (x 2 )
the tangential electrical displacement continuous boundary conditions are:
D T (x 2 + )＝D T (x 2 - )＝0
the normal stress continuous boundary conditions are:
T n (x 2 + )＝T n (x 2 - )＝0
the tangential stress continuous boundary conditions are:
T T (x 2 + )＝T T (x 2 - )＝0
wherein: x is x 2 + Is x 2 X is the upper surface of (x) 2 — Is x 2 Lower surface of sigma n Is a charge;
the contact surface x of the piezoelectric film layer and the piezoelectric substrate 3 Electrical and mechanical boundary conditions of (a):
the normal electric displacement continuous boundary conditions are:
D n (x 3 + )-D n (x 3 - )＝0
the tangential electrical displacement continuous boundary conditions are:
D T (x 3 + )＝D T (x 3 - )≠0
the normal stress continuous boundary conditions are:
T n (x 3 + )＝T n (x 3 - )≠0
the tangential stress continuous boundary conditions are:
T T (x 3 + )＝T T (x 3 - )≠0
then use x 1 、x 2 、x 3 The interface stress continuous boundary condition and the electric displacement continuous boundary condition are used for establishing an eigenvalue of the surface acoustic wave filter structure based on the heterogeneous integrated structure, and the eigenvalue is as follows:
wherein, at the insulating layer:
e＝0
wherein: c is the elastic constant of the material, e is the piezoelectric stress constant, epsilon is the dielectric constant, rho is the density, and u is the displacement.
8. The miniaturized saw filter structure of claim 6, further comprising a lower temperature patch layer between the piezoelectric substrate and the piezoelectric thin film layer, the lower temperature patch layer being made of a material having a positive temperature coefficient and the lower temperature patch layer completely covering the piezoelectric substrate surface and the piezoelectric thin film layer completely covering the lower temperature patch layer surface.
9. The miniaturized saw filter structure of claim 8, further comprising an upper temperature patch layer made of a material having a positive temperature coefficient, the upper temperature patch layer being located on the surface of the piezoelectric thin film layer and the upper temperature patch layer completely covering the insulating layer and the electrode layer.
10. The miniaturized surface acoustic wave filter structure according to claim 8 or 9, wherein a surface x of the piezoelectric thin film layer in contact with the insulating layer 1 Electrical and mechanical boundary conditions of (a):
the normal electric displacement continuous boundary conditions are:
D n (x 1 + )-D n (x 1 - )＝0
the tangential electrical displacement continuous boundary conditions are:
D T (x 1 + )＝D T (x 1 - )≠0
the normal stress continuous boundary conditions are:
T n (x 1 + )＝T n (x 1 - )≠0
the tangential stress continuous boundary conditions are:
T T (x 1 + )＝T T (x 1 - )≠0
wherein: x is x 1 + Is x 1 X is the upper surface of (x) 1 — Is x 1 Lower surface of D n For normal electric displacement, D T For tangential electrical displacement, T n Is normal stress, T T Is tangential stress;
a surface x of the piezoelectric thin film layer which is not contacted with the insulating layer 1 Electrical and mechanical boundary conditions of (a):
the normal electric displacement continuous boundary conditions are:
D n (x 1 + )-D n (x 1 - )＝σ n (x 1 )
the tangential electrical displacement continuous boundary conditions are:
D T (x 1 + )＝D T (x 1 - )＝0
the normal stress continuous boundary conditions are:
T n (x 1 + )＝T n (x 1 - )＝0
the tangential stress continuous boundary conditions are:
T T (x 1 + )＝T T (x 1 - )＝0
wherein: sigma (sigma) n Is a charge;
the contact surface x of the insulating layer and the electrode layer 2 Electrical and mechanical boundary conditions of (a):
the normal electric displacement continuous boundary conditions are:
D n (x 2 + )-D n (x 2 - )＝σ n (x 2 )
the tangential electrical displacement continuous boundary conditions are:
D T (x 2 + )＝D T (x 2 - )＝0
the normal stress continuous boundary conditions are:
T n (x 2 + )＝T n (x 2 - )＝0
the tangential stress continuous boundary conditions are:
T T (x 2 + )＝T T (x 2 - )＝0
wherein: x is x 2 + Is x 2 X is the upper surface of (x) 2 — Is x 2 Lower surface of sigma n Is a charge;
the contact surface x of the piezoelectric film layer and the lower temperature compensation layer 3 Electrical and mechanical boundary conditions of (a):
the normal electric displacement continuous boundary conditions are:
D n (x 3 + )-D n (x 3 - )＝0
the tangential electrical displacement continuous boundary conditions are:
D T (x 3 + )＝D T (x 3 - )≠0
the normal stress continuous boundary conditions are:
T n (x 3 + )＝T n (x 3 - )≠0
the tangential stress continuous boundary conditions are:
T T (x 3 + )＝T T (x 3 - )≠0
wherein: x is x 3 + Is x 3 X is the upper surface of (x) 3 — Is x 3 Is formed on the lower surface of the base plate;
the contact surface x of the lower temperature compensation layer and the piezoelectric substrate 4 Electrical and mechanical boundary conditions of (a):
the normal electric displacement continuous boundary conditions are:
D n (x 4 + )-D n (x 4 - )＝0
the tangential electrical displacement continuous boundary conditions are:
D T (x 4 + )＝D T (x 4 - )≠0
the normal stress continuous boundary conditions are:
T n (x 4 + )＝T n (x 4 - )≠0
the tangential stress continuous boundary conditions are:
T T (x 4 + )＝T T (x 4 - )≠0
wherein: x is x 4 + Is x 4 X is the upper surface of (x) 4 — Is x 4 Is formed on the lower surface of the base plate;
the temperature compensation principle of the lower temperature compensation layer is as follows:
ρ θ ＝ρ+ρ (1) θ+ρ (2) θ 2 +ρ (3) θ 3
r θ ＝r+r (1) θ+r (2) θ 2 +r (3) θ 3
g θ ＝g+g (1) θ+g (2) θ 2 +g (3) θ 3
θ＝(T-T 0 )
wherein, the liquid crystal display device comprises a liquid crystal display device,
is an n-order coefficient of elastic constant, +.>
Is an n-order coefficient of the piezoelectric stress constant, +.>
N-order coefficient of dielectric constant, delta ik Is the Kronecker operator, +.>
For the n-order thermal expansion temperature coefficient ρ (n) Is the n-order coefficient of density, r (n) N-order coefficient g of first Ramez constant of electrode layer (n) N-order coefficient, T, of the second Lame constant of the electrode layer 0 Is the reference temperature, T is the temperature environment, and θ is the temperature difference.
Then use x 1 、x 2 、x 3 And x 4 The interface stress continuous boundary condition and the electric displacement continuous boundary condition are used for establishing an eigenvalue of the surface acoustic wave filter structure based on the heterogeneous integrated structure, and the eigenvalue is as follows:
wherein, at insulating layer and piezoelectricity substrate:
eθ＝0
wherein: c (C) θ E is the elastic constant of the material changing with temperature θ Epsilon as the piezoelectric stress constant with temperature θ For a dielectric constant as a function of temperature ρ θ For density as a function of temperature, u is displacement.
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| CN101150302A (en) * | 2006-09-19 | 2008-03-26 | 富士通媒体部品株式会社 | Acoustic wave device and filter |
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| CN112653415A (en) * | 2020-12-25 | 2021-04-13 | 广东广纳芯科技有限公司 | Multilayer film surface acoustic wave resonator and manufacturing method thereof |
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|---|---|---|---|---|
| CN101150302A (en) * | 2006-09-19 | 2008-03-26 | 富士通媒体部品株式会社 | Acoustic wave device and filter |
| JP2013201468A (en) * | 2012-03-23 | 2013-10-03 | Kyocera Corp | Acoustic wave element and acoustic wave device using the same |
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