Stray shear horizontal mode frequency control in lithium niobate filter with high speed layer added

Abstract

The present invention relates to a spurious shear horizontal mode frequency control with the addition of a high velocity layer in a lithium niobate filter. In particular, to an electronic device comprising a first surface acoustic wave (SAW) resonator and a second SAW resonator, each SAW resonator having interleaved interdigital transducer (IDT) electrodes, the first SAW resonator and the second SAW resonator being formed on a same piezoelectric substrate, the first SAW resonator having IDT electrodes with a different interdigitated pitch than the IDT electrodes of the second SAW resonator; a layer of dielectric material disposed on the IDT electrodes of the first SAW resonator and the second SAW resonator; a high velocity layer disposed within the layer of dielectric material configured on the IDT electrodes of the first SAW resonator, the second SAW resonator not having a high velocity layer disposed within the layer of dielectric material configured on the IDT electrodes.

Description

[0001] Cross-references to related applications

[0002] This application claims priority to U.S. Provisional Patent Application US62 / 684,330, filed June 13, 2018, entitled “FREQUENCY CONTROL OF SPURIOUS SHEAR HORIZONTAL MODE BY ADDING HIGH VELOCITY LAYER IN A LITHIUM NIOBATE FILTER,” and U.S. Provisional Patent Application US62 / 693,027, filed July 2, 2018, entitled “FREQUENCY CONTROL OF SPURIOUS SHEAR HORIZONTAL MODE BY ADDING HIGH VELOCITY LAYER IN A LITHIUM NIOBATE FILTER.” Each of these applications is incorporated herein by reference in its entirety. Background Technology

[0003] In the field of information communication devices such as mobile phones, there is a growing desire to include additional features within the device while maintaining or reducing the space occupied by the device's electronic circuitry. Various information communication devices include filters for defining frequency bands used by the device to transmit and receive signals. These filters may include surface acoustic wave (SAW) elements formed on a piezoelectric substrate. One method for reducing the size of such filters may include forming multiple SAW elements for filters within a single integrated circuit or multiple filters within a single integrated circuit. Summary of the Invention

[0004] According to one aspect of this application, an electronic device is provided. The electronic device includes a first surface acoustic wave (SAW) resonator and a second SAW resonator, each SAW resonator having staggered interdigital transducer (IDT) electrodes. The first SAW resonator and the second SAW resonator are formed on the same piezoelectric substrate. The first SAW resonator has an IDT electrode with a different finger spacing than the IDT electrode of the second SAW resonator. A dielectric material layer is disposed on the IDT electrodes of the first and second SAW resonators. A high-speed layer is disposed within the dielectric material layer disposed on the IDT electrode of the first SAW resonator. The second SAW resonator does not have a high-speed layer disposed within the dielectric material layer disposed on the IDT electrode.

[0005] In some embodiments, the first SAW resonator exhibits a shear wave spurious mode having a resonant frequency higher than an anti-resonant frequency of a Rayleigh vibration mode of the first SAW resonator.

[0006] In some embodiments, the first SAW resonator and the second SAW resonator are electrically coupled to each other and included in a ladder filter, the ladder filter including at least one series SAW resonator electrically coupled in series between an input port and an output port of the ladder filter and at least one shunt SAW resonator electrically connected between a terminal of the at least one series SAW resonator and ground.

[0007] In some embodiments, the resonant frequency of the shear wave spurious mode occurs at a frequency outside a passband of the ladder filter.

[0008] In some embodiments, a cut angle of the piezoelectric substrate and a thickness of the dielectric material layer relative to an interdigital transducer pitch of the first SAW resonator are selected to minimize a strength of a shear wave at the resonant frequency of the shear wave spurious mode.

[0009] In some embodiments, the dielectric layer includes silicon dioxide.

[0010] In some embodiments, the high speed layer includes one or more of silicon nitride, silicon oxynitride, aluminum nitride, aluminum oxide, or diamond.

[0011] In some embodiments, the dielectric layer of the first SAW resonator is split into an upper layer and a lower layer by the high speed layer.

[0012] In some embodiments, the high speed layer is between about 0% and about 40% of a dielectric material thickness above IDT electrodes of the first SAW resonator.

[0013] In some embodiments, the electronic device is included in an electronic device module. The electronic device module can be a radio frequency device module.

[0014] According to another aspect, an electronic device is provided. The electronic device includes: a first filter and a second filter, each filter including surface acoustic wave (SAW) resonators disposed on a same piezoelectric substrate, the first filter having a passband different from a passband of the second filter; a dielectric film covering the SAW resonators of the first filter and the second filter; and a high speed layer disposed within the dielectric film covering the SAW resonators of the first filter, the second filter including one or more SAW resonators that do not have the high speed layer.

[0015] In some embodiments, a dielectric film covering at least one of the SAW resonators of the first filter has a different thickness than a dielectric film covering at least one of the SAW resonators of the second filter.

[0016] In some embodiments, a normalized height of the high-speed layer within the dielectric film covering at least one of the SAW resonators of the first filter is different than a normalized height of the high-speed layer within the dielectric film covering at least one of the SAW resonators of the second filter.

[0017] In some embodiments, the high-speed layer disposed within the dielectric film covering at least one of the SAW resonators of the first filter has a same thickness as the high-speed layer disposed within the dielectric film covering at least one of the SAW resonators of the second filter.

[0018] In some embodiments, the high-speed layer disposed within the dielectric film covering at least one of the SAW resonators of the first filter has a different thickness than the high-speed layer disposed within the dielectric film covering at least one of the SAW resonators of the second filter.

[0019] In some embodiments, a normalized thickness of the high-speed layer within the dielectric film covering at least one of the SAW resonators of the first filter is the same as a normalized thickness of the high-speed layer within the dielectric film covering at least one of the SAW resonators of the second filter.

[0020] In some embodiments, the dielectric film covering the SAW resonators of the first filter includes an upper portion disposed on an upper surface of the high-speed layer, and a lower portion disposed between a lower surface of the high-speed layer and an upper surface of an interdigital transducer electrode of at least one of the SAW resonators of the first filter.

[0021] In some embodiments, a thickness of a lower portion of the dielectric film covering at least one of the SAW resonators of the first filter has a different thickness than a lower portion of the dielectric film covering at least one of the SAW resonators of the second filter.

[0022] In some embodiments, a normalized height of the high-speed layer within the dielectric film covering at least one of the SAW resonators of the first filter is the same as a normalized height of the high-speed layer within the dielectric film covering at least one of the SAW resonators of the second filter.

[0023] In some embodiments, a normalized thickness of the high velocity layer within the dielectric film covering at least one of the SAW resonators of the first filter is different than a normalized thickness of the high velocity layer within the dielectric film covering at least one of the SAW resonators of the second filter.

[0024] In some embodiments, a thickness of the high velocity layer within the dielectric film covering at least one of the SAW resonators of the first filter has a different thickness than a thickness of the high velocity layer within the dielectric film covering at least one of the SAW resonators of the second filter.

[0025] In some embodiments, a normalized thickness of the high velocity layer within the dielectric film covering at least one of the SAW resonators of the first filter is the same as a normalized thickness of the high velocity layer within the dielectric film covering at least one of the SAW resonators of the second filter.

[0026] In some embodiments, at least one of the first filter or the second filter is a ladder filter including a plurality of series resonators and a plurality of shunt resonators, the high velocity layer being disposed within the dielectric film covering at least one of the plurality of series resonators and at least one of the plurality of shunt resonators.

[0027] In some embodiments, at least one of the first filter or the second filter is a multi-mode SAW filter.

[0028] In some embodiments, at least one of the first filter or the second filter is a dual-mode SAW filter.

[0029] In some embodiments, the electronic device is included in an electronic device module. The electronic device module can be a radio frequency device module.

[0030] According to yet another aspect, a surface acoustic wave (SAW) resonator is provided. The SAW resonator includes interleaved interdigital transducer (IDT) electrodes, a layer of dielectric material disposed on the IDT electrodes of the SAW resonator, and a high velocity layer disposed within the layer of dielectric material disposed on the IDT electrodes of the SAW resonator.

[0031] In some embodiments, the high velocity layer has a dimension sufficient to cause a frequency temperature coefficient of a resonant frequency of the SAW resonator to shift to be closer to zero as compared to a substantially similar SAW resonator without the high velocity layer.

[0032] In some embodiments, the IDT electrodes include a stack of at least two layers, each of the layers including a different material. BRIEF DESCRIPTION OF DRAWINGS

[0033] Various aspects of at least one embodiment are discussed in the following detailed description with reference to the drawing figures in which like numerals represent the same or similar elements. The drawing figures are intended to be illustrative, not limiting. Included in the drawing figures is an example of a ladder filter and a surface acoustic wave (SAW) resonator. The drawing figures are incorporated in and constitute a part of this specification, but are not intended to limit the applications' scope in any way. In the figures:

[0034] Figure 1 is a cross-sectional view of a portion of a surface acoustic wave (SAW) resonator;

[0035] Figure 2 is a schematic view of a portion of a ladder filter;

[0036] Figure 3 shows Figure 2 a frequency response of parameters of a ladder filter;

[0037] Figure 4 shows design parameters of a SAW resonator;

[0038] Figure 5 shows changes in a coupling coefficient (k 2 ) and a frequency temperature coefficient (TCF) as a function of dielectric layer thickness in an embodiment of a SAW resonator;

[0039] Figure 6 shows changes in strength of a shear mode spurious signal as a function of dielectric layer thickness and piezoelectric substrate cut angle in an embodiment of a SAW resonator.

[0040] Figure 7 schematically shows an embodiment of an integrated circuit including a plurality of ladder filters including SAW resonators formed on a common piezoelectric substrate;

[0041] Figure 8 is a cross-sectional view of a portion of a SAW resonator including a dielectric film layer and a high velocity layer disposed within the dielectric film layer;

[0042] Figure 9A shows a location of a shear mode spurious signal in an impedance parameter curve of a SAW resonator having no high velocity layer within a dielectric film layer of the SAW resonator;

[0043] Figure 9B shows a location of a shear mode spurious signal in an impedance parameter curve of a SAW resonator having a high velocity layer of a first thickness within a dielectric film layer of the SAW resonator;

[0044] Figure 9C A position of a shear mode spurious signal in an impedance parameter curve of a SAW resonator is shown, the SAW resonator having a high velocity layer of a second thickness within a dielectric film layer;

[0045] Figure 10 A frequency response of parameters of a ladder filter including a resonator is shown, the resonator including a dielectric film layer and a high velocity layer disposed within the dielectric film layer;

[0046] Figure 11 A frequency difference between a longitudinal vibration mode anti-resonance frequency and a shear mode spurious signal in an impedance parameter curve of a SAW resonator is shown;

[0047] Figure 12 A difference between a longitudinal vibration mode anti-resonance frequency and a shear mode spurious signal frequency in an impedance parameter curve of a SAW resonator is shown as a function of high velocity layer thickness and high velocity layer position within a dielectric film of the SAW resonator;

[0048] Figure 13A A cross-sectional view of a portion of a SAW resonator including a dielectric film layer and a high velocity layer disposed within the dielectric film layer at a first position is shown;

[0049] Figure 13B A cross-sectional view of a portion of a SAW resonator including a dielectric film layer and a high velocity layer disposed within the dielectric film layer at a second position is shown;

[0050] Figure 14 A coupling coefficient (k 2 ) in an impedance parameter curve of a SAW resonator is shown as a function of high velocity layer thickness and high velocity layer position within a dielectric film of the SAW resonator;

[0051] Figure 15 A quality factor in an impedance parameter curve of a SAW resonator is shown as a function of high velocity layer thickness and high velocity layer position within a dielectric film of the SAW resonator;

[0052] Figure 16A A cross-sectional view of a portion of a SAW resonator having a dielectric layer and a high velocity layer disposed in a center of the dielectric layer is shown;

[0053] Figure 16B A TCF of a longitudinal vibration mode resonance frequency of the resonator of FIG. 16 is shown as a function of dielectric layer thickness;

[0054] Figure 16C A TCF of a longitudinal vibration mode anti-resonance frequency of the resonator of Figure 16A is shown as a function of dielectric layer thickness;

[0055] Figure 17 is a schematic diagram of another ladder filter;

[0056] Figure 18 shows an example of film thickness difference of resonators of two filters formed on a common piezoelectric substrate;

[0057] Figure 19 shows another example of film thickness difference of resonators of two filters formed on a common piezoelectric substrate;

[0058] Figure 20 shows yet another example of film thickness difference of resonators of two filters formed on a common piezoelectric substrate;

[0059] Figure 21 shows yet another example of film thickness difference of resonators of two filters formed on a common piezoelectric substrate;

[0060] Figure 22A shows an embodiment of a SAW resonator;

[0061] Figure 22B shows an embodiment of a multi-mode SAW filter;

[0062] Figure 23 is a block diagram of a front-end module in which any of the filters disclosed herein can be implemented; and

[0063] Figure 24 is a block diagram of a wireless device in which any of the filters disclosed herein can be implemented. DETAILED DESCRIPTION

[0064] Aspects and embodiments disclosed herein include filter structures for wireless communication devices and methods of manufacturing the same that exhibit low levels of spurious shear modes within the passband of the filter. Particular embodiments include ladder filter structures that include acoustic wave elements having dielectric coatings with compositions and thicknesses selected to achieve desired parameters such as frequency temperature coefficients, quality factors and coupling coefficients, and minimum spurious shear modes within the passband of the filter.

[0065] Aspects and embodiments disclosed herein include RF filters constructed on a piezoelectric substrate such as LiNbO3 or LiTaO3 and having a ladder structure including series resonators and parallel resonators. The resonators can include surface acoustic wave (SAW) resonators including interleaved interdigital transducer (IDT) electrodes covered by a dielectric film such as SiO2 or by a combination of dielectric films such as SiO2 and Si3N4.

[0066] Figure 1A simplified cross-sectional view of an embodiment of a SAW resonator is shown in FIG. 1, generally designated 100. The SAW resonator 100 includes a plurality of IDT electrodes 105 disposed on a piezoelectric substrate 110. The piezoelectric substrate 110 can be composed of or include, for example, LiNb03, LiTa03, or other piezoelectric material. In Figure 1 In the particular embodiment shown, the piezoelectric substrate 110 is 128YX-cut LiNb03. The plurality of IDT electrodes 105 and the piezoelectric substrate 110 are covered by a layer of dielectric material 115, for example, silicon dioxide (Si02). In any of the embodiments disclosed herein, the layer of dielectric material 115 can be covered by a second layer of dielectric material, for example, silicon nitride (Si3N4), which can provide passivation and frequency trimming for the SAW resonator 100. This second layer of dielectric material is omitted from the figures for simplicity. The IDT electrodes 105 are shown in Figure 1 In FIG. 1, the plurality of IDT electrodes 105 are shown as including a lower layer 105A and an upper layer 105B. The lower layer 105A can include or be composed of, for example, tungsten or molybdenum, and the upper layer 105B can include or be composed of, for example, aluminum. Although the IDT electrodes shown in other figures of the present application are shown as including a single layer of material for simplicity, it should be understood that the IDT electrodes in any of the embodiments disclosed herein can be formed of a single material or multiple layers of different materials.

[0067] A plurality of SAW resonators can be assembled together to form a ladder filter. Figure 2 An embodiment of a portion of a ladder filter is shown in FIG. 2. The portion of the ladder filter includes a single series resonator Resl and a single shunt resonator Res2, the single series resonator Resl being connected in series between an input port Portl (port 1) and an output port Port2 (port 2) of the portion of the ladder filter, and the single shunt resonator Res2 being electrically connected in shunt between a terminal of the series resonator Resl and ground. The resonators Resl and Res2 can have different resonant and anti-resonant frequencies, the series resonator Resl typically having a higher resonant frequency than the resonant frequency of the shunt resonator Res2 and a higher anti-resonant frequency than the anti-resonant frequency of the shunt resonator Res2.

[0068] Figure 3The diagram shows a partial performance simulation of resonators Res1 and Res2, as well as a trapezoidal filter. Due to the presence of shear wave vibration modes generated during operation, the impedance parameter Y21 curves for the longitudinal wave (Rayleigh) vibration modes of resonators Res1 and Res2 show discontinuities at 305 and 310. These discontinuities in the impedance parameter curves of resonators Res1 and Res2 result in discontinuities at 315 and 320 in the transmission parameter S21 of the trapezoidal filter from port 1 to port 2. These discontinuities at 315 and 320 are undesirable because they degrade the performance of the trapezoidal filter.

[0069] The adjustable SAW resonator has various parameters including: the spacing between the IDT electrodes 105, which in turn defines the wavelength λ of the resonant frequency, and the thickness h of the dielectric layer 115. SiO2 And the cutting angle of the piezoelectric crystal substrate. Figure 4 These parameters are shown in the figure, where the cutting angle of the piezoelectric crystal substrate is indicated as "xxx".

[0070] like Figure 5 As shown, the thickness h of dielectric layer 115 SiO2 The temperature coefficient of frequency (TCF) of the SAW resonator and the coupling coefficient k between the IDT electrode 105 and the piezoelectric substrate 110 are affected. 2 Therefore, the relative thickness h of dielectric layer 115 SiO2 / λ is typically chosen to achieve the desired value for these parameters in the SAW resonator. Once the relative thickness h of the dielectric layer 115 is selected... SiO2 / λ allows us to select the cutting angle xxx of the piezoelectric crystal substrate to minimize the intensity of shear wave stray signals. For example... Figure 6 As shown, a cutting angle of 129 degrees can be selected to achieve a dielectric layer relative thickness h between 25% and 30%. SiO2 In embodiments using a / λ SAW resonator, shear wave spurious signals are minimized, while having a dielectric layer relative thickness h greater than approximately 35%. SiO2 In embodiments of the / λ SAW resonator, a shallower cut angle, such as approximately 127 degrees, can be suitable for suppressing shear wave spurious signals.

[0071] In some embodiments, such as Figure 7As shown schematically in FIG. 1, multiple filter sections, represented as filter sections fl, f2, f3, and f4, having different resonators Resl-Res8 with different resonant frequencies (and thus different λ parameters) can be formed in a single chip on a common piezoelectric substrate. Because the λ parameters of the different resonators of the different filter sections fl, f2, f3, and f4 can be different, different thicknesses h of the dielectric layer covering the IDT electrodes of the different filter sections can be needed SiO2 to obtain the relative thickness h of the dielectric layer for each resonator of these filter sections SiO2 / λ to provide the desired TCF and k for each resonator of each filter section 2 Forming regions of the dielectric layer 115 with different thicknesses in locations corresponding to different resonators presents a challenge for manufacturing. Moreover, once the relative thickness h of the dielectric layer for each resonator is selected SiO2 / λ, the cut angle of the piezoelectric crystalline substrate cannot be selected individually for each resonator to suppress spurious shear wave signals in each filter section because each filter section is formed on the same substrate.

[0072] It has been found that by adding a layer of material with a higher speed of sound than the dielectric material within the dielectric layer 115, the frequency at which a discontinuity appears in the impedance parameter curve of a SAW resonator due to the generation of a shear wave spurious mode can be shifted. The layer of material with a higher speed of sound than the dielectric layer 115 can be referred to as a "high speed layer". Figure 8 An example of a high speed layer 805 included in an embodiment of a SAW resonator, generally designated 800, is shown in FIG. 8. In embodiments where the dielectric layer 115 is Si02, the high speed layer 805 can include Si3N4, silicon oxynitride (SiON), aluminum nitride (AIN), aluminum oxide (AI2O3), diamond, or other materials known in the art with a higher speed of sound than Si02, or consist of Si3N4, silicon oxynitride (SiON), aluminum nitride (AIN), aluminum oxide (AI2O3), diamond, or other materials known in the art with a higher speed of sound than Si02. x N y ), aluminum nitride (AIN), aluminum oxide (AI2O3), diamond, or other materials known in the art with a higher speed of sound than Si02, or consist of Si3N4, silicon oxynitride (SiON), aluminum nitride (AIN), aluminum oxide (AI2O3), diamond, or other materials known in the art with a higher speed of sound than Si02. x N y ), aluminum nitride (AIN), aluminum oxide (AI2O3), diamond, or other materials known in the art with a higher speed of sound than Si02, or consist of Si3N4, silicon oxynitride (SiON), aluminum nitride (AIN), aluminum oxide (AI2O3), diamond, or other materials known in the art with a higher speed of sound than Si02. Figure 8 In FIG. 8, the thickness of the high speed layer 805 is denoted h, and the relative thickness of the high speed layer 805 is referred to herein as h / λ.

[0073] In embodiments where the dielectric layer 115 is divided into an upper portion 115A and a lower portion 115B by the high speed layer 805, the sum of the thicknesses of the upper portion 115A and the lower portion 115B is considered to be the thickness h of the dielectric layer 115 SiO2In embodiments where the dielectric layer 115 is divided into an upper portion 115A and a lower portion 115B by the high speed layer 805, the upper portion 115A and the lower portion 115B are collectively referred to herein as the dielectric layer 115. As with the dielectric layer 115 having the same relative thickness h Sio2 / λ, the presence of the high speed layer 805 can have an impact on the TCF and k SiO2 parameters of a resonator having a dielectric layer 115 with a relative thickness h 2 / λ. Thus, in embodiments where a high speed layer 805 is added to a resonator's dielectric layer 115 having a relative thickness h SiO2 / λ to achieve a desired TCF and k 2 parameters, the relative thickness h SiO2 / λ of the dielectric layer 115 can be adjusted to compensate for the impact of the high speed layer 805 on the TCF and k 2 parameters.

[0074] The impact of including a high speed layer 805 in a resonator's dielectric layer 115 as shown in FIG. 6 is shown in FIG. 7. Figure 9A-9C The impact of including a high speed layer 805 in a resonator's dielectric layer 115 as shown in FIG. 6 is shown in FIG. 7. Figure 8 The impedance parameter Y21 curve for a resonator without a high speed layer (relative thickness h / λ of zero) is shown. The discontinuity 905 in the impedance parameter curve is evident between the resonant frequency 910 and the anti-resonant frequency 915 of the resonator. Figure 9A The impact of adding a high speed layer 805 with a relative thickness h / λ of 1% to a resonator's dielectric layer 115 as shown in FIG. 6 is shown in FIG. 8. As compared to that shown in FIG. 7, the addition of the high speed layer 805 shifts the discontinuity 905 in the impedance parameter curve above the anti-resonant frequency 915 and also reduces the size of the discontinuity 905. Figure 9B The impact of adding a high speed layer 805 with a relative thickness h / λ of 1% to a resonator's dielectric layer 115 as shown in FIG. 6 is shown in FIG. 8. As compared to that shown in FIG. 7, the addition of the high speed layer 805 shifts the discontinuity 905 in the impedance parameter curve above the anti-resonant frequency 915 and also reduces the size of the discontinuity 905. Figure 8 The impact of adding a high speed layer 805 with a relative thickness h / λ of 4% to a resonator's dielectric layer 115 as shown in FIG. 6 is shown in FIG. 9. As compared to that shown in FIG. 8, the discontinuity 905 in the impedance parameter curve is further shifted upward and further reduced in size. Figure 9A The impact of adding a high speed layer 805 with a relative thickness h / λ of 4% to a resonator's dielectric layer 115 as shown in FIG. 6 is shown in FIG. 9. As compared to that shown in FIG. 8, the discontinuity 905 in the impedance parameter curve is further shifted upward and further reduced in size. Figure 9C Figure 8 Figure 9B The impact on filter performance of a filter similar to that shown in FIG. 10 when a high speed layer 805 is included in the resonator's dielectric layer 115 of the filter is shown in FIG. 11. The transmission parameter curve 1005 shown in FIG. 10 is compared to the transmission curve shown in FIG. 11, it is apparent that the frequency shift at the discontinuities 305, 310 in the impedance parameter curve of the resonator has eliminated the

[0075] Figure 10 The impact on filter performance of a filter similar to that shown in FIG. 10 when a high speed layer 805 is included in the resonator's dielectric layer 115 of the filter is shown in FIG. 11. The transmission parameter curve 1005 shown in FIG. 10 is compared to the transmission curve shown in FIG. 11, it is apparent that the frequency shift at the discontinuities 305, 310 in the impedance parameter curve of the resonator has eliminated the Figure 8 Figure 2 Figure 10 Figure 3 Figure 3 ​​​​​​The discontinuity in the impedance parameter curve shown at point 315 is significantly reduced. Figure 3 The inconsistency in magnitude is shown at 320, and the frequency is also shifted to be effectively outside the filter's passband.

[0076] return Figure 9A-9C The discontinuity of 905 in the longitudinal mode impedance parameter curve of the resonator corresponds to the resonance in the shear wave vibration mode of the resonator. For example... Figure 10 As shown, the performance of a trapezoidal filter including a SAW resonator can be improved by increasing the frequency difference between the anti-resonant frequency of the longitudinal wave vibration mode (Rayleigh mode) and the resonant frequency of the shear wave vibration mode. This frequency difference is... Figure 11 The frequency difference d is represented as the frequency difference. The frequency difference d can be a function of the thickness of the high-speed layer 805 and the position of the high-speed layer 805 within the dielectric layer 115 of the resonator. For example, as... Figure 12 As shown, the frequency difference d( Figure 12 "SH f" s -Raylef p "Parameters) with the relative thickness h / λ of the high-speed layer 805" Figure 12 The relative thickness h / λ of the high-speed layer 805 increases with the "SiN thickness / λ" parameter. In some embodiments, the relative thickness h / λ of the high-speed layer 805 is between about 0.1% and about 5%. As the position of the high-speed layer 805 in the dielectric layer 115 decreases, the frequency difference d generally also increases, although the frequency difference d decreases somewhat as the position of the high-speed layer 805 in the dielectric layer 115 decreases from 20% to 0% of the thickness of the dielectric layer 115. In this document, the position of the high-speed layer 805 in the dielectric layer 115 is described as a percentage of the thickness of the dielectric layer 115 disposed below the lower surface of the high-speed layer 805. Figure 8 The ratio t / T between the distances shown. Figure 13A and 13B The text further clarifies the meaning of the percentage thickness of the high-speed layer 805 at the location of the dielectric layer 115. For example... Figure 13A As shown, the location at 100% of the thickness of dielectric layer 115 is the top position of the entire dielectric layer 115. (As...) Figure 13B As shown, the position at 0% of the thickness of dielectric layer 115 is exactly located on top of IDT electrode 105 in dielectric layer 115.

[0077] The coupling coefficient k of the resonator 2 The quality factor Q can also depend on the thickness and location of the high-speed layer 805 in the dielectric layer 115. For example... Figure 14 As shown, the coupling coefficient k of the resonator 2may decrease with an increase in the relative thickness of the high-speed layer 805 (SiN thickness / λ) and increase with a decrease in the height of the location of the high-speed layer 805 in the dielectric layer 115. Similarly, as shown in Figure 15 the quality factor (Q) of the resonator can decrease with an increase in the relative thickness of the high-speed layer 805 (SiN thickness / λ) and increase with a decrease in the height of the location of the high-speed layer 805 in the dielectric layer 115.

[0078] In view of the relationships shown in Figure 12 , Figure 14 and Figure 15 , when the height of the location of the high-speed layer 805 in the dielectric layer 115 is less than about 40% of the thickness of the dielectric layer 115 above the top of the IDT electrodes but greater than about 2% of the thickness of the dielectric layer 115, desirable resonator parameters can be achieved. The relative thickness h / λ of the high-speed layer 805 (or the SiN thickness / λ as shown in Figure 12 , Figure 14 and Figure 15 may be selected to achieve a desired balance between the frequency difference between the anti-resonant frequency of the longitudinal wave vibration mode (Rayleigh mode) and the resonant frequency of the shear wave vibration mode of the resonator, the quality factor of the resonator, and the coupling coefficient of the resonator.

[0079] Figure 16B The TCF of the resonant frequency is shown in Figure 16A to vary with the relative dielectric layer thickness h SiO2 / λ of a resonator having a high-speed layer 805 disposed within the dielectric film 115 as shown in siO2 The dielectric layer thickness h SiO2 is the sum of the thickness of the upper portion 115A of the dielectric film 115 and the thickness of the lower portion 115B of the dielectric film 115. For comparison, Figure 16B the TCF of the resonant frequency is also shown in Figure 16A to vary with the relative dielectric layer thickness h SiO2 / λ of a resonator similar to Figure 16C The TCF of the anti-resonant frequency of the resonator of Figure 16A is shown in SiO2 to vary with the relative dielectric layer thickness h SiO2 / λ. For comparison, Figure 16C the TCF of the anti-resonant frequency is also shown in Figure 16A to vary with the relative dielectric layer thickness h SiO2 / λ of a resonator similar to Figure 16B and 16CIt can be seen that by including a high-speed layer 805 in the dielectric film layer 115, the TCF of both the resonant frequency and the anti-resonant frequency is improved (shifted to be closer to zero).

[0080] A trapezoidal filter may include multiple series resonators and multiple parallel resonators. The multiple series resonators are electrically coupled in series between the input port and the output port, and the multiple parallel resonators are connected between the terminals of the series resonators and ground. Figure 17 An example of a trapezoidal filter is schematically shown, where series resonators are represented by S1, S2, S3, and S4, and parallel resonators are represented by P1, P2, and P3. In some embodiments, the high-speed layer 805 may be formed only in the dielectric layer 115 of those resonators for which TCF is to be tuned, or only in the dielectric layer 115 of those resonators that exhibit spurious shear waves below their respective resonant and anti-resonant frequencies. For example, as... Figure 17 In some embodiments of the trapezoidal filter shown, only one or a subset of the parallel resonators, such as resonator P3, or one or a subset of the series resonators S1, S2, S3, and S4, may include a high-speed layer 805 formed in the dielectric layer 115 covering the IDT electrodes of the resonators, while the other resonators do not include a high-speed layer 805 formed in the dielectric layer 115 covering the corresponding IDT electrodes of the respective other resonators.

[0081] For example, Figure 7 As shown, an embodiment including multiple filters formed on a common piezoelectric substrate may include only a subset of filters, which may include resonators having a high-speed layer 805 formed in a dielectric layer 115 covering the IDT electrodes of one or more resonators of the filter subset. Alternatively, only a subset of filters may include resonators without the high-speed layer 805. For example, only a subset of filters may include a subset without the high-speed layer 805. For example, in Figure 7In the illustratively shown chip, filters fl and f4 can have a high speed layer 805 formed in a dielectric layer 115 that covers IDT electrodes of one or more resonators of the filter, while filters f2 and f3 do not. Alternatively, each of filters fl, f2, f3, and f4 can include at least one resonator that includes a high speed layer 805 disposed within a respective dielectric layer 115. In some embodiments, in a filter having a high speed layer 805 formed in a dielectric layer 115 that covers IDT electrodes of one or more resonators of the filter, the high speed layer 805 can be formed over at least one series resonator and at least one shunt resonator. In other embodiments, in a filter having a high speed layer 805 formed in a dielectric layer 115 that covers IDT electrodes of one or more resonators of the filter, the high speed layer 805 can be formed over each series resonator and over each shunt resonator.

[0082] In filters having resonators with different resonant and anti-resonant frequencies or in chips including filters having different passbands, the relative thicknesses of the upper and lower portions 115A and 115B of the dielectric layer 115 and the high speed layer 805 in different resonators or filters can be selected according to different criteria. In one example of a chip 1800 including a first filter fl and a second filter f2, where the passband of filter fl is at a lower frequency than the passband of filter f2, the IDT electrodes 105 of the resonators in filter fl can have longer periods than the IDT electrodes 105 in the resonators of filter f2. In some embodiments, the upper portion 115A on the dielectric layer 155 on the resonator(s) having the narrower (smaller) IDT electrode period can be etched back to align the normalized thickness h SiO2 / λ in the resonators having the larger IDT electrode period with the resonators having the narrower IDT electrode period. Aligning the normalized thickness h SiO2 / λ in the resonators having the larger IDT electrode period with the resonators having the narrower IDT electrode period can provide similar coupling coefficients k 2 , TCF, and levels of shear mode spurious signals (see Figure 5 and Figure 6 ). Figure 18 Examples of this embodiment are shown in

[0083] In the modified chip 1800, an etch-back layer 805 is disposed above the IDT electrode 105 in the resonator of filter f2 to align the normalized thickness h / λ between the resonators of the two filters. This provides similar frequency differences, similar quality factors, and similar coupling coefficients k between the anti-resonant frequencies of the longitudinal wave vibration mode (Rayleigh mode) and the resonant frequencies of the shear wave vibration mode for different resonators. 2 (see Figure 12 , Figure 14 and Figure 15 ). Figure 19 An example of this embodiment is shown in its entirety at 1900.

[0084] In another embodiment of the chip 2000 including a first filter f1 and a second filter f2, wherein the passband of filter f1 is at a lower frequency than the passband of filter f2, and the IDT electrode 105 of the resonator in filter f1 has a longer period than the IDT electrode 105 of the resonator in filter f2, a lower portion 115B of the dielectric film 115 disposed above the IDT electrode 105 of the resonator in filter f2 is etched back to achieve normalized height alignment of the high-speed layer 805 within the dielectric layer 115 between the resonators of the different filters. This provides the frequency difference, quality factor, and coupling coefficient k between the anti-resonant frequency of the longitudinal wave vibration mode (Rayleigh mode) and the resonant frequency of the shear wave vibration mode in each different resonator. 2 Optimization (see) Figure 12 , 14 and 15). Figure 20 An example of this embodiment is shown in the figure.

[0085] In the modified chip 2000, a high-speed layer 805 is disposed above the IDT electrode 105 in the resonator of filter f2 to align the normalized thickness h / λ between the resonators of the two filters. This provides different resonators with similar frequency differences, similar quality factors, and similar coupling coefficients k between the anti-resonant frequencies of the longitudinal wave vibration mode (Rayleigh mode) and the resonant frequencies of the shear wave vibration mode. 2 (see Figure 12 , Figure 14 and Figure 15 ). Figure 21 An example of this embodiment is shown in its entirety at 2100.

[0086] Figure 18-21 Different combinations of the thicknesses of the dielectric layer 115 and the high-speed layer 85 shown can be applied to different resonators within a single filter or different resonators in different filters.

[0087] Any of the aspects and embodiments disclosed herein can be used in a SAW resonator, examples of which are shown in Figure 22A , or in a multi-mode SAW filter, examples of which are shown in Figure 22B . Figure 22B The multi-mode SAW filter of

[0088] The filters as shown in any of the above referenced embodiments can be used in electronics for wide frequency bands.

[0089] Referring to Figure 23 , a block diagram of one example of a front-end module 2200 is shown, which can be used, for example, in electronics such as wireless communication devices (e.g., mobile phones). The front-end module 2200 includes an antenna duplexer 2210 having a common node 2212, an input node 2214, and an output node 2216. An antenna 2310 is connected to the common node 2212. The front-end module 2200 also includes a transmitter circuit 2232 connected to the input node 2214 of the duplexer 2210 and a receiver circuit 2234 connected to the output node 2216 of the duplexer 2210. The transmitter circuit 2232 can generate signals for transmission via the antenna 2310, and the receiver circuit 2234 can receive and process signals received via the antenna 2310. As shown in Figure 23 , in some embodiments, the receiver and transmitter circuits are implemented as separate components; however, in other embodiments, these components can be integrated into a common transceiver circuit or module. As will be appreciated by those skilled in the art, the front-end module 2200 can include other components not shown in Figure 23 , including but not limited to switches, electromagnetic couplers, amplifiers, processors, etc.

[0090] The antenna duplexer 2210 can include one or more transmit filters 2222 connected between the input node 2214 and the common node 2212, and one or more receive filters 2224 connected between the common node 2212 and the output node 2216. The passband(s) of the transmit filter(s) are different from the passband(s) of the receive filters. Each of the transmit filter(s) 2222 and the receive filter(s) 2224 can include embodiments of filters as disclosed herein. An inductor or other matching component 2240 can be connected at the common node 2212.

[0091] In some examples, the acoustic elements used in the transmit filter 2222 and / or receive filter 2224 are disposed on a single piezoelectric substrate. This structure reduces the effect of temperature variations on the frequency response of the respective filters, particularly reducing the degradation of the pass or attenuation characteristics of the filters due to temperature variations, since each acoustic element in each filter changes similarly in response to changes in ambient temperature. In cases where the temperature of the first filter changes due to heat conducted through the substrate from the second filter to the first filter, the use of a high-speed layer in the dielectric film within the first filter further reduces the degradation of pass or attenuation characteristics. Additionally, this arrangement (disposed on a single piezoelectric substrate) allows for a small size for either the transmit filter 2222 or the receive filter 2224.

[0092] Figure 24 It includes Figure 23 The diagram shows an example block diagram of a wireless device 2300 with antenna duplexer 2210 shown. Wireless device 2300 can be a cellular phone, smartphone, tablet, modem, communication network, or any other portable or non-portable device configured for voice or data communication. Wireless device 2300 can receive and transmit signals from antenna 2310. The wireless device includes components similar to those referenced above. Figure 23 An embodiment of the front-end module 2200' is discussed. As described above, the front-end module 2200' includes a duplexer 2210. Figure 24 In the example shown, the front-end module 2200' also includes an antenna switch 2250, which is configurable to switch between different frequency bands or modes, such as switching between transmit and receive modes. Figure 24 In the example shown, antenna switch 2250 is located between duplexer 2210 and antenna 2310; however, in other examples, duplexer 2210 may be located between antenna switch 2250 and antenna 2310. In other examples, antenna switch 2250 and duplexer 2210 may be integrated into a single component.

[0093] The front-end module 2200' includes a transceiver 2230, which is configured to generate signals for transmission or to process received signals. For example... Figure 23 As shown in the example, transceiver 2230 may include transmitter circuitry 2232 and receiver circuitry 2234. Transmitter circuitry 2232 may be connected to input node 2214 of duplexer 2210, and receiver circuitry 2234 may be connected to output node 2216 of duplexer 2210.

[0094] The generated signals transmitted by the transmitter circuit 2232 are received by a power amplifier (PA) module 2260, which amplifies the generated signals from the transceiver 2230. The power amplifier module 2260 can include one or more power amplifiers. The power amplifier module 2260 can be used to amplify various RF or other band transmit signals. For example, the power amplifier module 2260 can receive an enable signal, which can be used to pulse the output of the power amplifier to help send wireless local area network (WLAN) signals or any other suitable pulsed signals. The power amplifier module 2260 can be configured to amplify any of various types of signals, including, for example, global system for mobile (GSM) signals, code division multiple access (CDMA) signals, W-CDMA signals, long term evolution (LTE) signals, or EDGE signals. In certain embodiments, the power amplifier module 2260 and related components, including switches, can be fabricated using, for example, high electron mobility transistors (pHEMTs) or insulated gate bipolar transistors (BiFETs) on a gallium arsenide (GaAs) substrate, or complementary metal oxide semiconductor (CMOS) field effect transistors on a silicon substrate.

[0095] With continued reference to Figure 24 The front-end module 2200' can also include a low noise amplifier module 2270 that amplifies received signals from the antenna 2310 and provides the amplified signals to the receiver circuit 2234 of the transceiver 2230.

[0096] Figure 24 The wireless device 2300 also includes a power management subsystem 2320 connected to the transceiver 2230 and managing power for operation of the wireless device 2300. The power management system 2320 can also control operation of the baseband subsystem 2330 and various other components of the wireless device 2300. The power management system 2320 can include or be connected to a battery (not shown) that provides power to the various components of the wireless device 2300. The power management system 2320 can also include one or more processors or controllers that, for example, can control transmission of signals. In one embodiment, the baseband subsystem 2330 is connected to a user interface 2340 to facilitate various inputs and outputs of voice and / or data to and from a user. The baseband subsystem 2330 can also be connected to a memory 2350 configured to store data and / or instructions to facilitate operation of the wireless device and / or to provide storage of information for the user.

[0097] Having described aspects of at least one embodiment above, it is to be understood that various alterations, modifications and improvements will readily occur to those skilled in the art. Such alterations, modifications and improvements are intended to be part of this disclosure, and are intended to be within the scope of the application. It should be understood that the embodiments of the methods and devices discussed herein are not limited to the details of the foregoing description, nor to the details of the construction and the arrangement of the components set forth in the following description or illustrated in the drawings. The methods and devices are capable of implementation in other embodiments and of being practiced or carried out in various ways. Examples of specific implementations are provided herein for illustrative purposes only, and are not intended to be limiting. One or more features of any of the embodiments disclosed herein can be added to or substituted for any other embodiment or one or more features of any other embodiment. Also, the phraseology and terminology used herein is for the purpose of description and not of limitation. The use of terms such as “including,” “comprising,” “having,” “containing,” “involving,” “characterized by,” “characterized into” and variations thereof herein is meant to encompass the items listed thereafter and equivalents thereof as well as additional items. The use of “or” can be construed as inclusive, so that any term described using “or” can indicate any of a singular, a plurality, and all of the described terms. Any references to front and back, left and right, top and bottom, upper and lower, and vertical and horizontal are intended for convenience, and are not to be construed as limiting the system and method or their components to any one position or spatial orientation. Accordingly, the foregoing description and drawings are by way of example only.

Claims

1. An electronic device, comprising: a first surface acoustic wave (SAW) resonator and a second SAW resonator, each SAW resonator having interleaved interdigital transducer (IDT) electrodes, the first SAW resonator and the second SAW resonator being formed on a same piezoelectric substrate, the first SAW resonator having IDT electrodes with a different interdigitated pitch than IDT electrodes of the second SAW resonator; a dielectric film disposed on the IDT electrodes of the first SAW resonator and the second SAW resonator; and a high speed layer disposed within the dielectric film configured on the IDT electrodes of the first SAW resonator and within the dielectric film configured on the IDT electrodes of the second SAW resonator, a normalized thickness of the high speed layer within the dielectric film covering the IDT electrodes of the first SAW resonator being different than a normalized thickness of the high speed layer within the dielectric film covering the IDT electrodes of the second SAW resonator. the first SAW resonator exhibits a shear wave spurious mode having a resonant frequency that is higher than an anti-resonant frequency of a Rayleigh vibration mode of the first SAW resonator.

2. Electronic device according to claim 1, wherein, the first SAW resonator and the second SAW resonator are electrically coupled to each other and included in a ladder filter, the ladder filter including at least one series SAW resonator electrically coupled in series between an input port and an output port of the ladder filter and at least one shunt SAW resonator electrically connected between a terminal of the at least one series SAW resonator and ground.

3. The electronic device of claim 2, wherein, the resonant frequency of the shear wave spurious mode occurs at a frequency outside a passband of the ladder filter.

4. The electronic device of claim 3, wherein, a cut angle of the piezoelectric substrate and a thickness of the dielectric film relative to the interdigitated pitch of the first SAW resonator are selected to minimize a strength of a shear wave at the resonant frequency of the shear wave spurious mode.

5. The electronic device of claim 4, wherein, the dielectric film includes silicon dioxide.

6. The electronic device of claim 5, wherein, the high speed layer includes one or more of silicon nitride, silicon oxynitride, aluminum nitride, aluminum oxide, or diamond.

7. The electronic device of claim 6, wherein, the dielectric film of the first SAW resonator is divided into an upper layer and a lower layer by the high speed layer.

8. The electronic device of claim 7, wherein, the high speed layer is between about 0% and about 40% of a thickness of dielectric material above the IDT electrodes of the first SAW resonator.

9. The electronic device of claim 8, wherein, 10. The electronic device of claim 1, included in an electronic device module. the electronic device module is a radio frequency device module.

11. The electronic device of claim 10, wherein, 12. An electronic device, comprising: a first filter and a second filter, each filter including surface acoustic wave (SAW) resonators disposed on a same piezoelectric substrate, the first filter having a passband that is different than a passband of the second filter; a dielectric film covering the SAW resonators of the first filter and the second filter; and a high speed layer disposed within the dielectric film configured on the SAW resonators of the first filter and within the dielectric film configured on the SAW resonators of the second filter. ​ a high velocity layer disposed within the dielectric film covering at least one of the SAW resonators of the first filter and the SAW resonators of the second filter, the second filter including one or more SAW resonators without the high velocity layer, a normalized height of the high velocity layer within the dielectric film covering the SAW resonators of the first filter being different than a normalized height of the high velocity layer within the dielectric film covering at least one of the SAW resonators of the second filter.

13. The electronic device of claim 12, wherein, the dielectric film covering at least one of the SAW resonators of the first filter has a different thickness than the dielectric film covering at least one of the SAW resonators of the second filter.

14. The electronic device of claim 12, wherein, the high velocity layer disposed within the dielectric film covering at least one of the SAW resonators of the first filter has a same thickness as the high velocity layer disposed within the dielectric film covering at least one of the SAW resonators of the second filter.

15. The electronic device of claim 12, wherein, the high velocity layer disposed within the dielectric film covering at least one of the SAW resonators of the first filter has a different thickness than the high velocity layer disposed within the dielectric film covering at least one of the SAW resonators of the second filter.

16. The electronic device of claim 15, wherein, a normalized thickness of the high velocity layer within the dielectric film covering at least one of the SAW resonators of the first filter is the same as a normalized thickness of the high velocity layer within the dielectric film covering at least one of the SAW resonators of the second filter.

17. The electronic device of claim 13, wherein, the dielectric film covering the SAW resonators of the first filter includes an upper portion disposed on an upper surface of the high velocity layer and a lower portion disposed between a lower surface of the high velocity layer and an upper surface of an interdigital transducer electrode of at least one of the SAW resonators of the first filter.

18. The electronic device of claim 17, wherein, a thickness of the lower portion of the dielectric film covering at least one of the SAW resonators of the first filter has a different thickness than a lower portion of the dielectric film covering at least one of the SAW resonators of the second filter.

19. The electronic device of claim 18, wherein, a normalized height of the high velocity layer within the dielectric film covering at least one of the SAW resonators of the first filter is the same as a normalized height of the high velocity layer within the dielectric film covering at least one of the SAW resonators of the second filter.

20. The electronic device of claim 19, wherein, a normalized thickness of the high velocity layer within the dielectric film covering at least one of the SAW resonators of the first filter is different than a normalized thickness of the high velocity layer within the dielectric film covering at least one of the SAW resonators of the second filter.

21. The electronic device of claim 17, wherein, a thickness of the high velocity layer within the dielectric film covering at least one of the SAW resonators of the first filter has a different thickness than a thickness of the high velocity layer within the dielectric film covering at least one of the SAW resonators of the second filter.

22. The electronic device of claim 21, wherein, a normalized thickness of the high velocity layer within the dielectric film covering at least one of the SAW resonators of the first filter is the same as a normalized thickness of the high velocity layer within the dielectric film covering at least one of the SAW resonators of the second filter.

23. The electronic device of claim 12, wherein, At least one of the first filter or the second filter is a ladder filter including a plurality of series resonators and a plurality of parallel resonators, the high-speed layer is disposed within the dielectric film covering at least one of the plurality of series resonators and at least one of the plurality of parallel resonators.

24. The electronic device of claim 12, wherein, At least one of the first filter or the second filter is a multi-mode SAW filter.

25. The electronic device of claim 24, wherein, At least one of the first filter or the second filter is a dual-mode SAW filter.

26. The electronic device of claim 12, the electronic device included in an electronic device module.

27. The electronic device of claim 26, wherein, The electronic device module is a radio frequency device module.

28. An electronic device, comprising: first and second surface acoustic wave (SAW) resonators each having interleaved interdigital transducer (IDT) electrodes, the first and second SAW resonators formed on a same piezoelectric substrate, the first SAW resonator having IDT electrodes having a different interdigitated pitch than IDT electrodes of the second SAW resonator; a dielectric film disposed on the IDT electrodes of the first and second SAW resonators; and a high-speed layer disposed within the dielectric film configured on the IDT electrodes of the first SAW resonator and within the dielectric film configured on the IDT electrodes of the second SAW resonator, a normalized height of the high-speed layer within the dielectric film covering the IDT electrodes of the first SAW resonator being different than a normalized height of the high-speed layer within the dielectric film covering the IDT electrodes of the second SAW resonator.

29. The electronic device of claim 28, wherein, The dielectric film disposed on the IDT electrodes of the first SAW resonator has a different thickness than the dielectric film disposed on the IDT electrodes of the second SAW resonator.

30. The electronic device of claim 28, wherein the dielectric film disposed on the IDT electrodes of the first SAW resonator has a different normalized thickness than a normalized thickness of the dielectric film disposed on the IDT electrodes of the second SAW.

31. The electronic device of claim 29, wherein, The high-speed layer disposed within the dielectric film configured on the IDT electrodes of the first SAW resonator has a same normalized height as the high-speed layer disposed within the dielectric film configured on the IDT electrodes of the second SAW resonator.

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