Bulk acoustic wave resonator, method of determining a doping concentration, filter, and electronic device
By optimizing the layer thickness ratio E/P and doping concentration of the bulk acoustic resonator, the problem of simultaneously improving kt2 and Q value in the prior art was solved, and high-performance filter design was achieved.
Patent Information
- Application Number
- CN202011061186.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2020-09-30
- Publication Date
- 2026-01-23
- Estimated Expiration
- 2040-09-30
AI Technical Summary
In the prior art, it is difficult to improve the Q value of thin-film bulk acoustic resonators while maintaining a large electromechanical coupling coefficient kt2.
By selecting appropriate layer thickness ratios E/P and doping concentrations, the doping elements of the piezoelectric layer can be optimized to improve the electromechanical coupling coefficient Kt2 of the resonator, while maintaining or increasing the Q value of the resonator.
While ensuring a high Q value for the resonator, the electromechanical coupling coefficient Kt2 was significantly improved, meeting the filter's requirement for a large bandwidth.
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Figure CN114337571B_ABST
Abstract
Description
TECHNICAL FIELD
[0001] Embodiments of the present application relate to the field of semiconductor, and in particular, to a bulk acoustic wave resonator and a method for determining a doping concentration, and a filter and an electronic device. BACKGROUND
[0002] With the development of 5G communication technology, the communication technology puts forward higher and higher requirements for the large bandwidth of the filter. Under this premise, the design of the filter puts forward an urgent demand for the resonator with a larger effective electromechanical coupling coefficient (kt 2 ).
[0003] As a new type of MEMS device, the film bulk acoustic resonator (FBAR) has the advantages of small size, light weight, low insertion loss, wide frequency band, and high quality factor, which well adapts to the upgrading of wireless communication systems.
[0004] In the prior art, there is still a demand to improve the Q value of the resonator while maintaining a large kt 2 . SUMMARY
[0005] To alleviate or solve at least one aspect of the above problems in the prior art, the present application is proposed.
[0006] According to an aspect of an embodiment of the present application, a bulk acoustic wave resonator is provided, comprising:
[0007] a substrate;
[0008] an acoustic mirror;
[0009] a bottom electrode;
[0010] a piezoelectric layer, the piezoelectric layer being a piezoelectric layer comprising a doping element, the doping element having a corresponding doping concentration; and
[0011] a top electrode,
[0012] wherein:
[0013] the resonator has a layer thickness ratio E / P;
[0014] the resonator has an electromechanical coupling coefficient Kt 2 , the doping concentration is not less than a1, a1 is the electromechanical coupling coefficient Kt 2 corresponding to the doping concentration when the layer thickness ratio E / P of the resonator is 0.75.
[0015] Embodiments of the present application also relate to a method for determining a doping concentration, the doping concentration being a doping concentration of a doping element of a piezoelectric layer of a bulk acoustic wave resonator, the resonator having an electromechanical coupling coefficient Kt 2, the resonator having a layer thickness ratio E / P, the method comprising the steps of:
[0016] selecting the doping concentration to be not less than a1 based on the layer thickness ratio E / P, a1 being the electromechanical coupling coefficient Kt 2 corresponding to the layer thickness ratio E / P = 0.75.
[0017] Embodiments of the present application also relate to a filter comprising the above-described resonator.
[0018] Embodiments of the present application also relate to an electronic device comprising the above-described filter or the above-described resonator. BRIEF DESCRIPTION OF DRAWINGS
[0019] The following description with the accompanying drawings can better help understand these and other features and advantages of the various embodiments disclosed by the present application, in which the same reference numerals are always used to designate the same components, in which:
[0020] Figure 1 is a schematic cross-sectional view of a bulk acoustic wave resonator;
[0021] Figure 2 is a graph exemplarily showing the relationship between the E / P value and the width of the protruding structure and the Q value of the resonator;
[0022] Figure 3 is a graph exemplarily showing the relationship between the width of the protruding structure and the Q value of the resonator;
[0023] Figure 4 is a graph exemplarily showing the relationship between the E / P value and the Kt 2 ;
[0024] Figure 5 is a graph exemplarily showing the relationship between the doping concentration and the Kt 2 , where E / P = 1;
[0025] Figure 6 is a graph exemplarily showing the relationship between the doping concentration and the Kt 2 , where E / P = 0.75;
[0026] Figure 7 is a graph exemplarily showing the relationship between the doping concentration and the Kt 2 , where E / P = 0.85;
[0027] Figure 8 is a graph exemplarily showing the relationship between the doping concentration and the Kt 2 , where E / P = 1.15;
[0028] Figure 9 is a graph exemplarily showing the relationship between the doping concentration and the Kt 2 , where E / P = 1.25. DETAILED DESCRIPTION
[0029] The technical solutions of the present application are further specifically described below by way of examples in conjunction with the accompanying drawings. In the description, identical or similar reference numerals indicate identical or similar components. The following description of the embodiments of the present application with reference to the accompanying drawings is intended to explain the general inventive concept of the present application and should not be understood as a limitation of the present application. The description is directed to some embodiments of the present application, but not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art belong to the scope of protection of the present application.
[0030] Figure 1 A cross-sectional view of a typical sandwich structure bulk acoustic wave resonator is shown. Figure 1 In the drawings, the following reference numerals are used:
[0031] 101: substrate, which can be made of single crystal silicon, gallium nitride, gallium arsenide, sapphire, quartz, silicon carbide, diamond, etc.
[0032] 102: acoustic mirror, which can be a cavity, or can be a Bragg reflection layer or other equivalent form. In the embodiments of the present application, the cavity form is used.
[0033] 103: bottom electrode (including bottom electrode pin), which can be made of molybdenum, ruthenium, gold, aluminum, magnesium, tungsten, copper, titanium, iridium, osmium, chromium, or a composite of the above metals or an alloy thereof, etc.
[0034] 104: piezoelectric layer, which can be a single crystal piezoelectric material, which can be selected from, for example, single crystal aluminum nitride, single crystal gallium nitride, single crystal lithium niobate, single crystal lead zirconate titanate (PZT), single crystal potassium niobate, single crystal quartz thin film, or single crystal lithium tantalate, etc. The piezoelectric layer can also be a polycrystalline piezoelectric material (as opposed to a single crystal material, which is a non-single crystal material), which can be selected from, for example, polycrystalline aluminum nitride, zinc oxide, PZT, etc. The piezoelectric layer can also be a rare earth element doped material containing the above materials in a certain atomic ratio, for example, doped aluminum nitride, which contains at least one rare earth element such as scandium (Sc), yttrium (Y), magnesium (Mg), titanium (Ti), lanthanum (La), cerium (Ce), praseodymium (Pr), neodymium (Nd), promethium (Pm), samarium (Sm), europium (Eu), gadolinium (Gd), terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb), and lutetium (Lu).
[0035] 105: top electrode (including top electrode pin), which can be made of molybdenum, ruthenium, gold, aluminum, magnesium, tungsten, copper, titanium, iridium, osmium, chromium, or a composite of the above metals or an alloy thereof, etc.
[0036] 106: passivation layer or process layer, which can be aluminum nitride, silicon nitride, or silicon dioxide, etc.
[0037] 107: protrusion structure, material can be selected from molybdenum, ruthenium, gold, aluminum, magnesium, tungsten, copper, titanium, iridium, osmium, chromium or alloy of the above metals.
[0038] For the bulk acoustic wave resonator, the electromechanical coupling coefficient Kt 2 related to the value of the layer thickness ratio E / P and the doping concentration of the doping element in the piezoelectric layer. In addition, the Q value of the bulk acoustic wave resonator is related to the value of the layer thickness ratio E / P.
[0039] The present application proposes a scheme for improving the performance of the resonator by selecting the doping concentration based on a specific layer thickness ratio, so that both a higher resonator Q value and a higher Kt 2 .
[0040] The layer thickness ratio E / P is briefly described below.
[0041] As Figure 1 shown, the thickness of the bottom electrode 103 is t1, the thickness of the piezoelectric layer 104 is t2, the thickness of the top electrode 105 is t3, and the thickness of the passivation layer 106 above the top electrode is t4. When the passivation layer 106 is not provided, the ratio of the electrode thickness to the piezoelectric layer thickness, i.e. the layer thickness ratio E / P, is defined as (t1+t3) / t2. When the resonator has a passivation layer 106, the ratio of the electrode thickness to the piezoelectric layer thickness, i.e. the layer thickness ratio E / P, is defined as (t1+t3+t4*a) / t2, where a is related to the ratio of the influence rate of the thickness of the passivation layer 106 on the resonator resonance frequency Fs and the influence rate of the thickness of the top electrode 105 on the resonator resonance frequency Fs. Specifically, assuming that the influence rate of the thickness of the passivation layer 106 on the resonator resonance frequency Fs is V1 nm / MHz, and the influence rate of the thickness of the top electrode 105 on the resonator resonance frequency Fs is V2 nm / MHz, then a = V2 / V1. If the top electrode and the bottom electrode are made of Mo and the passivation layer is made of AlN, then the value of a is close to 1 / 3. If the stacked structure of the resonator is increased by other functional layers on the basis of the above, the layer thickness ratio E / P can also be calculated based on the above concept.
[0042] The doping concentration of the doping element in the piezoelectric layer is briefly described below.
[0043] Doping means that part of one or more elements in the original undoped piezoelectric material is replaced by a doping element. At this time, the doping concentration is defined as the ratio of the number of atoms of the doping element to the sum of the number of atoms of the one or more elements replaced by the doping element in a unit volume. For example, in the case of an aluminum nitride piezoelectric layer and a doping element of scandium, part of the aluminum atoms is replaced by scandium atoms, and the doping concentration is the ratio of the number of scandium atoms to the sum of the number of aluminum atoms and the number of scandium atoms in a unit volume (Sc / Al+Sc).
[0044] Figure 2 The relationship between the layer thickness ratio E / P value and the width of the protruding structure and the Q value of the resonator is shown. Figure 2 In the figure, the ordinate is the Q value of the resonator, and the abscissa has two layers, the first layer is the layer thickness ratio E / P of the resonator, and the second layer is the width L (unit: μm) of the protruding structure 107. Based on the first layer, Figure 2 The relationship between the Q value of the resonator and the layer thickness ratio E / P in the Band1 TX frequency band (1920-1980 MHz) is shown. Based on the second layer, Figure 2 The Q value of the resonator at different protruding structure widths L under different layer thickness ratios E / P is shown.
[0045] Figure 3 The relationship between the width L of the protruding structure and the Q value of the resonator when the layer thickness ratio E / P = 1 is shown. From Figure 3 It can be seen that the Q value of the resonator changes with the change of the protruding width L, and there are two peaks in the Q value when the protruding width L = 1.25 um and L = 5.25 um. However, referring to Figure 2 When the layer thickness ratio E / P is less than 1, Figure 3 The peaks of the two Q values in the figure will deteriorate as the layer thickness ratio E / P decreases. Referring to Figure 2 When E / P = 0.65, in Figure 3 The two maximum values of the Q value in the figure are deteriorated by more than 20%, and the maximum value at L = 1.25 no longer exists.
[0046] Therefore, the value of the layer thickness ratio E / P can directly affect the size of the Q value of the resonator. In order to obtain a better Q value of the resonator, the value of the layer thickness ratio E / P should not be less than 0.75.
[0047] Figure 4 The relationship between the E / P value and the kt 2 is shown, where the abscissa is the E / P value and the ordinate is the kt 2 . More specifically, Figure 4 The relationship between the kt 2 and the layer thickness ratio E / P is shown when the piezoelectric layer is a piezoelectric layer of aluminum nitride doped with a metal scandium element, and the doping concentration is 8.2%. It can be seen that the kt 2 increases as the layer thickness ratio E / P decreases. However, under the premise of ensuring that the performance of the resonator is not deteriorated seriously, it is concluded from Figure 2 that kt 2 cannot be improved by infinitely reducing the E / P value.
[0048] Figure 5 The relationship between the doping concentration and the kt 2 is shown. InFigure 5 In the figure, the abscissa is the doping concentration, and the ordinate is Kt 2 , where E / P = 1, it can be seen that, as the doping concentration increases, Kt 2 increases.
[0049] Therefore, by selecting a higher value of the layer thickness ratio E / P, for example, the value of the layer thickness ratio E / P should not be less than 0.75, to ensure that the Q value of the resonator is high (but at this time Kt 2 does not meet the performance requirements or does not fully meet the performance requirements), and by selecting a doping concentration above a predetermined value to improve Kt 2 to meet the performance requirements or to improve the performance. Therefore, under the premise of ensuring the performance of the resonator (high Q value), the doping concentration can be improved to improve Kt 2 .
[0050] Since Kt 2 is related to the value of the layer thickness ratio E / P and the doping concentration, and the value of E / P has a lower limit value (as previously explained, not less than 0.75), even if Kt 2 is desired to be as large as possible, Kt 2 also has an upper limit value, which is determined by the lower limit value of E / P, which is 0.75.
[0051] In other words, in the present application, for a bulk acoustic wave filter, the kt 2 of the resonator can be improved by selecting the doping concentration. However, for a resonator with a selected kt 2 , there is an optimal range of doping concentrations to ensure high performance of the resonator.
[0052] Based on the above, the present application proposes a bulk acoustic wave resonator, whose piezoelectric layer is a piezoelectric layer containing a doping element, the doping element has a corresponding doping concentration, the resonator has an electromechanical coupling coefficient Kt 2 , and the doping concentration is not less than a1, a1 is the electromechanical coupling coefficient Kt 2 corresponding to the doping concentration when the layer thickness ratio E / P of the resonator is 0.75.
[0053] Based on the above, the present application also proposes a method for determining the doping concentration of the piezoelectric layer of a bulk acoustic wave resonator, comprising the steps of: based on the layer thickness ratio E / P, selecting a doping concentration not less than a1, a1 is the electromechanical coupling coefficient Kt 2 corresponding to the doping concentration when the layer thickness ratio E / P of the resonator is 0.75.
[0054] Figures 5-9 Exemplary examples are shown when the piezoelectric layer is a piezoelectric layer of aluminum nitride doped with a metal scandium element, the layer thickness ratio E / P takes different values, and the doping concentration and Kt 2The relationship is shown in the graphs. In these graphs, the horizontal axis represents the doping concentration, and the vertical axis represents Kt. 2 .exist Figures 5-9 As can be seen from the diagram, as the doping concentration increases, Kt... 2 It also increases.
[0055] Figure 5 The example illustrates that when the piezoelectric layer is an aluminum nitride-doped scandium layer, the doping concentration and Kt are related when the layer thickness ratio E / P = 1. 2 The relationship between doping concentration a5 and Kt can be obtained through fitting. 2 The relationship is Kt 2 =0.4147a5 2 +0.2774a5+0.057. In Figure 5 In the middle, Kt 2 Let y be a5 and x be a5.
[0056] Figure 6 The example illustrates that when the piezoelectric layer is an aluminum nitride-doped scandium piezoelectric layer, with a layer thickness ratio E / P = 0.75, the doping concentration and Kt are... 2 The relationship between doping concentration a1 and Kt can be obtained through fitting. 2 The relationship is Kt 2 =0.3909a1 2 +0.3056a1+0.062. In Figure 6 In the middle, Kt 2 Let y be a1 and x be a1.
[0057] Figure 7 The example illustrates that when the piezoelectric layer is an aluminum nitride-doped scandium layer, with a layer thickness ratio E / P = 0.85, the doping concentration and Kt are... 2 The relationship between doping concentration a2 and Kt can be obtained through fitting. 2 The relationship is Kt 2 =0.4463a2 2 +0.2869a2+0.0603. In Figure 7 In the middle, Kt 2 Let y be a1 and x be a2.
[0058] Figure 8 The example illustrates that when the piezoelectric layer is an aluminum nitride-doped scandium layer, with a layer thickness ratio E / P = 1.15, the doping concentration and Kt are... 2 The relationship between doping concentration a4 and Kt can be obtained through fitting. 2 The relationship is Kt 2 =0.3829a4 2 +0.2825a4+0.0547. InFigure 8 In the middle, Kt 2 Let y be a4 and x be a4.
[0059] Figure 9 The example illustrates that when the piezoelectric layer is an aluminum nitride-doped scandium layer, with a layer thickness ratio E / P = 1.25, the doping concentration and Kt are... 2 The relationship between doping concentration a3 and Kt can be obtained through fitting. 2 The relationship is Kt 2 =0.3791a3 2 +0.2805a3+0.0528. In Figure 9 In the middle, Kt 2 Let y be a3 and x be a3.
[0060] As mentioned above, the doping concentration is not less than a1, where a1 is the electromechanical coupling coefficient Kt when the resonator layer thickness ratio E / P = 0.75. 2 The corresponding doping concentration. This is for a bulk acoustic resonator, at its Kt... 2 Given a specific situation, a lower limit for the doping concentration is specified.
[0061] In a more specific embodiment of the present invention, when the piezoelectric layer is an aluminum nitride-doped scandium layer, the lower limit value of the doping concentration a1 is the electromechanical coupling coefficient Kt when the layer thickness ratio E / P = 0.75. 2 The corresponding doping concentration is determined by the following formula: Kt 2 =0.3909a1 2 +0.3056a1+0.062.
[0062] The lower limit of the doping concentration can be further increased. In one embodiment of the present invention, the doping concentration is not less than a2, where a2 is the electromechanical coupling coefficient Kt when the resonator layer thickness ratio E / P = 0.85. 2 The corresponding doping concentration. In a more specific embodiment of the present invention, when the piezoelectric layer is an aluminum nitride-doped scandium piezoelectric layer, the lower limit value of the doping concentration a2 is the electromechanical coupling coefficient Kt when the layer thickness ratio E / P = 0.85. 2 The corresponding doping concentration is determined by the following formula: Kt 2 =0.4463a2 2 +0.2869a2+0.0603.
[0063] See Figure 2 When the layer thickness ratio E / P is not less than 1, the Q value of the resonator can be higher. Therefore, the lower limit of the doping concentration can be further increased. In one embodiment of the present invention, the doping concentration is not less than a5, where a5 is the electromechanical coupling coefficient Kt when the resonator layer thickness ratio E / P = 1.2 The corresponding doping concentration. In a more specific embodiment of the present invention, when the piezoelectric layer is an aluminum nitride-doped scandium piezoelectric layer, the lower limit value of the doping concentration a5 is the electromechanical coupling coefficient Kt when the layer thickness ratio E / P = 1. 2 The corresponding doping concentration is determined by the following formula: Kt 2 =0.4147a5 2 +0.2774a5+0.057.
[0064] In one embodiment of the present invention, an upper limit for the doping concentration may be further defined.
[0065] In one embodiment of the present invention, the doping concentration is not greater than a3, where a3 is Kt when the resonator layer thickness ratio E / P = 1.25. 2 The corresponding doping concentration. In a more specific embodiment, when the piezoelectric layer is an aluminum nitride-doped scandium layer, a3 is determined by the following formula: Kt 2 =0.3791a3 2 +0.2805a3+0.0528.
[0066] The upper limit can be further lowered. In one embodiment of the invention, the doping concentration is no greater than a4, where a4 is Kt when the resonator layer thickness ratio E / P = 1.15. 2 The corresponding doping concentration. In a more specific embodiment, when the piezoelectric layer is an aluminum nitride-doped scandium layer, a4 is determined by the following formula: Kt 2 =0.3829a4 2 +0.2825a4+0.0547.
[0067] The resonators described above (with appropriate doping concentrations selected based on the layer thickness ratio E / P) can also be used as filters.
[0068] In one embodiment of the invention, when the filter is a Band 1 band filter (TX (1920MHz–1980MHz), RX (2110MHz–2170MHz)) or a Band 3 band filter (TX (1710MHz–1785MHz), RX (1805MHz–1880MHz)), the doping concentration of the resonator in the filter meets the above requirements (e.g., different lower limits, and / or different lower and upper limits) and is in the range of 4.6%–10.2%, further in the range of 5.4%–9.1%. In this invention, TX represents a transmitting filter, and RX represents a receiving filter.
[0069] In one embodiment of the present application, in the case of a filter for a 2.515GHz-2.675GHz frequency band or a 3.3GHz-3.6GHz frequency band, the doping concentration of the resonator in the filter satisfies the above requirements (e.g. different lower limit values, and / or different lower limit values and upper limit values) and is in the range of 13.4%-22.1%, further in the range of 14.2%-20.6%.
[0070] In the above embodiments of the present application, it is explained that the piezoelectric layer doping concentration of the resonator is selected based on the selected value of the layer thickness ratio E / P, so that a higher Q value of the resonator can be ensured while also having a higher Kt 2 value of the resonator is improved. The present application provides an effective guidance scheme for how to select the doping concentration of the doping element of the piezoelectric layer.
[0071] As can be understood by those skilled in the art, the material of the piezoelectric layer is not limited to aluminum nitride, but can also be other piezoelectric materials listed in the present application, and the doping element is not limited to scandium metal, but can also be other dopable metal elements listed in the present application. Although in the specific embodiments of the present application, the doping of scandium element in aluminum nitride is taken as an example to explain how to select the piezoelectric layer doping concentration of the resonator based on the selected value of the layer thickness ratio E / P, but as can be understood by those skilled in the art, a suitable doping concentration based on the corresponding Kt 2 value of the resonator (so that the Kt 2 value of the resonator is higher) can also be selected based on a suitable value of the layer thickness ratio E / P of the resonator (so that the Q value of the resonator is higher, e.g. the value of the layer thickness ratio E / P is not less than 0.75).
[0072] It should be noted that in the present application, each numerical range, in addition to explicitly indicating that the end point value is not included, in addition to being able to be an end point value, can also be a median value of each numerical range, which is within the protection scope of the present application.
[0073] As can be understood by those skilled in the art, bulk acoustic wave resonators can be used to form other semiconductor devices in addition to filters.
[0074] Based on the above, the present application proposes the following technical solutions:
[0075] 1. A bulk acoustic wave resonator, comprising:
[0076] a substrate;
[0077] an acoustic mirror;
[0078] a bottom electrode;
[0079] a piezoelectric layer, the piezoelectric layer being a piezoelectric layer comprising a doping element, the doping element having a corresponding doping concentration; and
[0080] a top electrode,
[0081] wherein:
[0082] the resonator has a layer thickness ratio E / P;
[0083] the resonator has a electromechanical coupling coefficient Kt 2 corresponding to a doping concentration not less than a1, a1 being the electromechanical coupling coefficient Kt 2 corresponding to a layer thickness ratio E / P = 0.75.
[0084] 2. The resonator according to 1, wherein:
[0085] the piezoelectric layer is an aluminum nitride layer doped with a scandium element, a1 being determined by the following equation: Kt 2 = 0.3909a1 2 + 0.3056a1 + 0.062.
[0086] 3. The resonator according to 1, wherein:
[0087] the doping concentration is not less than a2, a2 being the electromechanical coupling coefficient Kt 2 corresponding to a layer thickness ratio E / P = 0.85.
[0088] 4. The resonator according to 3, wherein:
[0089] the piezoelectric layer is an aluminum nitride layer doped with a scandium element, a2 being determined by the following equation: Kt 2 = 0.4463a2 2 + 0.2869a2 + 0.0603.
[0090] 5. The resonator according to 3, wherein:
[0091] the doping concentration is not less than a5, a5 being the electromechanical coupling coefficient Kt 2 corresponding to a layer thickness ratio E / P = 1.00.
[0092] 6. The resonator according to 5, wherein:
[0093] the piezoelectric layer is an aluminum nitride layer doped with a scandium element, a5 being determined by the following equation: Kt 2 = 0.4147a5 2 + 0.2774a5 + 0.057.
[0094] 7. The resonator according to any one of 1 to 6, wherein:
[0095] The doping concentration is not more than a3, a3 is the electromechanical coupling coefficient Kt when the resonator layer thickness ratio E / P=1.25 2 The corresponding doping concentration.
[0096] 8. The resonator according to 7, wherein:
[0097] The piezoelectric layer is an aluminum nitride layer doped with a scandium element, and a3 is determined by the following formula: Kt 2 = 0.3791a3 2 + 0.2805a3+0.0528.
[0098] 9. The resonator according to 7, wherein:
[0099] The doping concentration is not more than a4, a4 is the electromechanical coupling coefficient Kt when the resonator layer thickness ratio E / P=1.15 2 The corresponding doping concentration.
[0100] 10. The resonator according to 9, wherein:
[0101] The piezoelectric layer is an aluminum nitride layer doped with a scandium element, and a4 is determined by the following formula: Kt 2 = 0.3829a4 2 + 0.2825a4+0.0547.
[0102] 11. A filter comprising a plurality of bulk acoustic wave resonators according to any one of 1-10.
[0103] 12. The filter according to 11, wherein:
[0104] The filter is a filter of Band1 frequency band or Band3 frequency band; and
[0105] The doping concentration of the resonators in the filter is in the range of 4.6%-10.2%.
[0106] 13. The filter according to 12, wherein:
[0107] The doping concentration of the resonators in the filter is in the range of 5.4%-9.1%.
[0108] 14. The filter according to 11, wherein:
[0109] The filter is a filter of 2.515GHz-2.675GHz frequency band or 3.3GHz-3.6GHz frequency band; and
[0110] The doping concentration of the resonators in the filter is in the range of 13.4%-22.1%.
[0111] 15. The filter according to 14, wherein:
[0112] The doping concentration of the resonator in the filter is in the range of 14.2%-20.6%.
[0113] 16. A method for determining a doping concentration of a doping element of a piezoelectric layer of a bulk acoustic wave resonator, the resonator having an electromechanical coupling coefficient Kt 2 , the resonator having a layer thickness ratio E / P, the method comprising the steps of:
[0114] selecting the doping concentration to be no less than a1 based on the layer thickness ratio E / P, a1 being the electromechanical coupling coefficient Kt 2 corresponding to the doping concentration when the layer thickness ratio E / P of the resonator is 0.75.
[0115] 17. The method according to 16, wherein:
[0116] the piezoelectric layer is an aluminum nitride layer doped with a scandium element, and a1 is determined by the following equation: Kt 2 = 0.3909a1 2 + 0.3056a1+0.062.
[0117] 18. The method according to 16 or 17, wherein:
[0118] the doping concentration is no more than a3, a3 being the electromechanical coupling coefficient Kt 2 corresponding to the doping concentration when the layer thickness ratio E / P of the resonator is 1.25.
[0119] 19. The method according to 18, wherein:
[0120] the piezoelectric layer is an aluminum nitride layer doped with a scandium element, and a3 is determined by the following equation: Kt 2 = 0.3791a3 2 + 0.2805a3+0.0528.
[0121] 20. An electronic device comprising the filter according to any one of 11-15, or the bulk acoustic wave resonator according to any one of 1-10.
[0122] The electronic device herein includes but is not limited to intermediate products such as radio frequency front end, filter amplification module, and terminal products such as mobile phone, WIFI, and unmanned aerial vehicle.
[0123] While embodiments of the application have been shown and described, it is to be understood that the embodiments described are merely exemplary of the principles and application of the present application. Numerous modifications and adaptations will be readily apparent to those of ordinary skill in this art in view of the foregoing description. This application is to be limited only by the following claims, and the equivalents thereof.
Claims
1. A bulk acoustic resonator, comprising: Base; Acoustic mirror; Bottom electrode; A piezoelectric layer, wherein the piezoelectric layer includes doped elements, and the doped elements have a corresponding doping concentration; and Top electrode, in: The resonator has a layer thickness ratio E / P; The resonator has an electromechanical coupling coefficient Kt 2 The doping concentration is not less than a1, where a1 is the electromechanical coupling coefficient Kt corresponding to a layer thickness ratio E / P = 0.
75. 2 The corresponding doping concentration, the electromechanical coupling coefficient Kt of the bulk acoustic resonator 2 The Q value of the bulk acoustic resonator is related to the layer thickness ratio E / P and the doping concentration of the doped elements in the piezoelectric layer.
2. The resonator according to claim 1, wherein: The piezoelectric layer is an aluminum nitride layer doped with scandium, and a1 is determined by the following formula: Kt 2 =0.3909a1 2 +0.3056a1+0.
062.
3. The resonator according to claim 1, wherein: The doping concentration is not less than a2, where a2 is the electromechanical coupling coefficient Kt corresponding to a resonator layer thickness ratio E / P = 0.
85. 2 The corresponding doping concentration.
4. The resonator according to claim 3, wherein: The piezoelectric layer is an aluminum nitride layer doped with scandium, and a2 is determined by the following formula: Kt 2 =0.4463a2 2 +0.2869a2+0.0603.
5. The resonator according to claim 3, wherein: The doping concentration is not less than a5, where a5 is the electromechanical coupling coefficient Kt corresponding to a resonator layer thickness ratio E / P = 1.
00. 2 The corresponding doping concentration.
6. The resonator according to claim 5, wherein: The piezoelectric layer is an aluminum nitride layer doped with scandium, and a5 is determined by the following formula: Kt 2 =0.4147a5 2 +0.2774a5+0.
057.
7. The resonator according to any one of claims 1-6, wherein: The doping concentration is no greater than a3, where a3 is the electromechanical coupling coefficient Kt corresponding to a resonator layer thickness ratio E / P = 1.
25. 2 The corresponding doping concentration.
8. The resonator according to claim 7, wherein: The piezoelectric layer is an aluminum nitride layer doped with scandium, and a3 is determined by the following formula: Kt 2 =0.3791a3 2 +0.2805a3+0.0528.
9. The resonator according to claim 7, wherein: The doping concentration is no greater than a4, where a4 is the electromechanical coupling coefficient Kt corresponding to a resonator layer thickness ratio E / P = 1.
15. 2 The corresponding doping concentration.
10. The resonator according to claim 9, wherein: The piezoelectric layer is an aluminum nitride layer doped with scandium, and a4 is determined by the following formula: Kt 2 =0.3829a4 2 +0.2825a4+0.0547.
11. A filter comprising a plurality of bulk acoustic resonators according to any one of claims 1-10.
12. The filter according to claim 11, wherein: The filter is a Band 1 or Band 3 frequency band filter; and The doping concentration of the resonator in the filter is in the range of 4.6% to 10.2%.
13. The filter according to claim 12, wherein: The doping concentration of the resonator in the filter is in the range of 5.4% to 9.1%.
14. The filter according to claim 11, wherein: The filter is a filter in the 2.515GHz-2.675GHz frequency band or the 3.3GHz-3.6GHz frequency band; and The doping concentration of the resonator in the filter is in the range of 13.4% to 22.1%.
15. The filter according to claim 14, wherein: The doping concentration of the resonator in the filter is in the range of 14.2% to 20.6%.
16. A method for determining doping concentration, wherein the doping concentration is the doping concentration of the doping element in the piezoelectric layer of a bulk acoustic wave resonator, the resonator having an electromechanical coupling coefficient Kt. 2 The resonator has a layer thickness ratio E / P, and the method includes the steps of: Based on the layer thickness ratio E / P, the doping concentration is selected to be not less than a1, where a1 is the electromechanical coupling coefficient Kt corresponding to a resonator layer thickness ratio E / P = 0.
75. 2 The corresponding doping concentration, the electromechanical coupling coefficient Kt of the bulk acoustic resonator 2 The Q value of the bulk acoustic resonator is related to the layer thickness ratio E / P and the doping concentration of the doped elements in the piezoelectric layer.
17. The method of claim 16, wherein: The piezoelectric layer is an aluminum nitride layer doped with scandium, and a1 is determined by the following formula: Kt 2 =0.3909a1 2 +0.3056a1+0.
062.
18. The method according to claim 16 or 17, wherein: The doping concentration is no greater than a3, where a3 is the electromechanical coupling coefficient Kt corresponding to a resonator layer thickness ratio E / P = 1.
25. 2 The corresponding doping concentration.
19. The method of claim 18, wherein: The piezoelectric layer is an aluminum nitride layer doped with scandium, and a3 is determined by the following formula: Kt 2 =0.3791a3 2 +0.2805a3+0.0528.
20. An electronic device comprising a filter according to any one of claims 11-15, or a bulk acoustic resonator according to any one of claims 1-10.
Citation Information
Patent Citations
Bulk acoustic wave resonator having doped piezoelectric layer
CN104883153A