Lamb wave resonator and manufacturing method thereof

Abstract

The present invention discloses a Lamb wave resonator and a method for manufacturing the same. The Lamb wave resonator comprises: a piezoelectric material layer; a first finger-shaped electrode disposed on one side of the piezoelectric material layer, the first finger-shaped electrode comprising a first main body and a plurality of first branches; a second finger-shaped electrode disposed on the one side of the piezoelectric material layer, the second finger-shaped electrode comprising a second main body and a plurality of second branches, wherein each first branch is parallel to each second branch and is arranged in an alternating manner; at least two floating electrodes disposed between each first branch and each second branch; and at least two gaps, respectively disposed at both ends of each floating electrode.

Description

Technical Field

[0001] The present invention relates to a resonator, and in particular to a Lamb wave resonator and a manufacturing method thereof. Background Art

[0002] In the 5G communications industry, communication devices must be equipped with appropriate filters, such as radio frequency electronic signal filters, to allow specific signals in electromagnetic wave signals to be input into the signal processor in the communication device, or to allow radio frequency electronic signals to be output from the communication device.

[0003] Generally speaking, a resonator can be used as a filter for electronic signals. For example, a resonator can be a Lamb wave resonator, which is configured with a piezoelectric layer and finger-shaped electrodes, each of which includes multiple equally spaced branches. By adjusting the spacing between the branches, the resonant frequency of the resonator can be changed, thereby allowing electronic signals of a specific frequency to pass through the resonator while filtering out electronic signals of other frequencies.

[0004] However, because the resonant frequency of a resonator is related to the spacing between its branches, filtering electronic signals in different frequency ranges often requires redesigning the branch layout and creating the corresponding photomask. This not only increases manufacturing complexity but also increases overall production time and cost.

[0005] Therefore, it is necessary to provide an improved Lamb wave resonator and a manufacturing method thereof to solve the problems faced by existing Lamb wave resonators. Summary of the Invention

[0006] In view of this, the present invention provides a Lamb wave resonator and a manufacturing method thereof to solve the technical problems faced by the prior art.

[0007] According to one embodiment of the present invention, a Lamb wave resonator is provided, comprising: a piezoelectric material layer; a first finger-shaped electrode disposed on one side of the piezoelectric material layer, the first finger-shaped electrode comprising a first main body and a plurality of first branches; a second finger-shaped electrode disposed on the one side of the piezoelectric material layer, the second finger-shaped electrode comprising a second main body and a plurality of second branches, wherein each first branch is parallel to each second branch and is arranged in an alternating manner; at least two floating electrodes disposed between each first branch and each second branch; and at least two gaps, respectively disposed at both ends of each floating electrode.

[0008] According to another embodiment of the present invention, a method for manufacturing a Lamb wave resonator is provided, comprising: providing a piezoelectric material layer; forming a first finger electrode on one side of the piezoelectric material layer, wherein the first finger electrode includes a plurality of first branches; forming a dielectric layer covering the piezoelectric material layer and the plurality of first branches; forming at least one first opening in the dielectric layer, the at least one first opening overlapping a portion of the plurality of first branches; and removing the portion of the plurality of first branches overlapping the at least one first opening to form at least two first floating electrodes.

[0009] According to the above embodiments, by truncating branches at specific spacings, the resonant frequency of a Lamb wave resonator can be lowered, for example, the resonant frequency of the S0 mode. Therefore, when fabricating a Lamb wave resonator with a different resonant frequency, there is no need to redesign the layout or spacing of the branches in the finger electrodes of the Lamb wave resonator. Instead, a specific mask pattern of the finger electrodes can be utilized, coupled with a subsequent removal process, to truncate the branches at specific spacings, thereby achieving the effect of lowering the resonant frequency of the Lamb wave resonator. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 is a schematic top view of a Lamb wave resonator according to an embodiment of the present invention;

[0011] Figure 2 An embodiment of the present invention is Figure 1 The cross-sectional view shown by the A-A' tangent line;

[0012] Figure 3 An embodiment of the present invention is Figure 1 The cross-sectional view shown by the BB' tangent line;

[0013] Figure 4 An embodiment of the present invention is Figure 1 The cross-sectional view shown by the C-C' tangent line;

[0014] Figure 5 A variation of the present invention is as follows Figure 1 The cross-sectional view shown by the A-A' tangent line;

[0015] Figure 6 A variation of the present invention is as follows Figure 1 The cross-sectional view shown by the BB' tangent line;

[0016] Figure 7 is a change in the resonant frequency of the Lamb wave resonator before and after the branch portion is cut off according to an embodiment of the present invention;

[0017] Figure 8is a schematic top view of a Lamb wave resonator according to a variant embodiment of the present invention;

[0018] Figure 9 is a schematic top view of a Lamb wave resonator according to a variant embodiment of the present invention;

[0019] Figure 10 This is a variation of the present invention. Figure 1 The cross-sectional view shown by the A-A' tangent line;

[0020] Figure 11 This is a variation of the present invention. Figure 1 The cross-sectional view shown by the A-A' tangent line;

[0021] Figure 12 This is a variation of the present invention. Figure 1 The cross-sectional view shown by the A-A' tangent line;

[0022] Figure 13 is a schematic top view of a Lamb wave resonator fabricated according to an embodiment of the present invention;

[0023] Figure 14 This is an embodiment of the present invention along Figure 13 The cross-sectional view shown by the A-A' tangent line;

[0024] Figure 15 is a schematic cross-sectional view of an embodiment of the present invention after the sacrificial layer is removed;

[0025] Figure 16 It is a cross-sectional schematic diagram of a modified embodiment of the present invention after a portion of the second branch portion is removed.

[0026] Description of reference numerals:

[0027] 100, 200, 300, 400, 500, 600, 700, 800, 900: Lamb wave resonator

[0028] 102: Framework

[0029] 104: Suspension

[0030] 105: Anchoring

[0031] 106, 152: Piezoelectric material layer

[0032] 110: First finger electrode

[0033] 112: Main cadre

[0034] 114: First Branch

[0035] 116: First floating electrode

[0036] 118: First insulation zone

[0037] 120: Second finger electrode

[0038] 122: Second Chief

[0039] 124: Second Branch

[0040] 126: Second floating electrode

[0041] 128: Second insulation zone

[0042] 130, 144, 606: Cavity

[0043] 132: Sacrificial layer

[0044] 140: Base

[0045] 142: Dielectric base

[0046] 146: Seed layer

[0047] 150: bottom electrode

[0048] 154: Passivation layer

[0049] 156, 506: dielectric layer

[0050] 158-1: First contact pad

[0051] 158-2: Second contact pad

[0052] 160: Interval

[0053] 170: Patterned photoresist

[0054] 172: Opening

[0055] 504: Wire

[0056] 602: First semiconductor layer

[0057] 608: Insulation layer

[0058] 610: Second semiconductor layer

[0059] G1, G1', G2, G2': Clearance

[0060] L1: First distance

[0061] L2: Second distance

[0062] L3: Third distance

[0063] O1: First opening

[0064] O2: Second opening

[0065] P1: First spacing

[0066] P2: Second spacing

[0067] P3: third pitch

[0068] P4: fourth pitch

[0069] P5: Fifth pitch

[0070] T1, T2, T3: thickness

[0071] W1, W1', W2, W2': Width

[0072] λ: wavelength

[0073] Δf: frequency difference DETAILED DESCRIPTION

[0074] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0075] The present invention provides several different embodiments that can be used to implement different features of the present invention. For simplicity of description, the present invention also describes examples of specific components and arrangements. These embodiments are provided for illustrative purposes only and are not intended to be limiting.

[0076] In the present invention, the description of "a first component is formed on or above a second component" may mean "the first component is in direct contact with the second component" or "there is another component between the first component and the second component", so that the first component and the second component are not in direct contact.

[0077] In addition, various embodiments of the present invention may use repeated element symbols and / or text annotations. The use of these repeated element symbols and text annotations is to make the description more concise and clear, rather than to indicate the relationship between different embodiments and / or configurations.

[0078] In addition, with respect to the spatially related descriptive terms mentioned in the present invention, such as "under," "over," "low," "high," "below," "above," "under," "above," "bottom," "top," and similar terms, for ease of description, their usage is to describe the relative relationship between one component or feature and another (or multiple) components or features in the accompanying drawings. In addition to the orientations shown in the accompanying drawings, these spatially related terms are also used to describe the possible orientations of semiconductor devices during the manufacturing process, use, and operation. For example, when the semiconductor device is rotated 180 degrees, a component that was originally positioned "above" other components will become positioned "below" the other components. Therefore, as the orientation of the semiconductor device changes (rotated 90 degrees or other angles), the spatially related descriptions used to describe its orientation should also be interpreted in a corresponding manner.

[0079] Although the present invention uses terms such as first, second, and third to describe various elements, components, regions, layers, and / or sections, it should be understood that these elements, components, regions, layers, and / or sections should not be limited by these terms. These terms are merely used to distinguish one element, component, region, layer, and / or block from another element, component, region, layer, and / or block, and do not imply or represent any prior number of the elements, nor do they represent the order in which one element is arranged relative to another element, or the order in which one element is manufactured. Therefore, without departing from the scope of the specific embodiments of the present invention, the first element, component, region, layer, or block discussed below may also be referred to as the second element, component, region, layer, or block.

[0080] The terms "couple," "coupled," and "electrically connected" mentioned in this disclosure include any direct and indirect electrical connection means. For example, if a first component is described as being coupled to a second component, it means that the first component can be directly electrically connected to the second component or indirectly electrically connected to the second component through other devices or connection means.

[0081] Although the present invention is described below with reference to specific embodiments, the principles of the present invention may also be applied to other embodiments. In addition, in order not to obscure the spirit of the present invention, certain details may be omitted, and the omitted details belong to the knowledge of those skilled in the art.

[0082] Figure 1 FIG. 1 is a schematic top view of a Lamb wave resonator according to an embodiment of the present invention. Figure 1As shown, the Lamb wave resonator 100 may include a frame portion 102 and a suspension portion 104, wherein the frame portion 102 may surround the periphery of the suspension portion 104 and may be connected to the suspension portion 104 via an anchor portion 105. A cavity or spacer 160 may exist below the suspension portion 104 and between the suspension portion 104 and the frame portion 102. Therefore, when the Lamb wave resonator 100 resonates, the suspension portion 104 may oscillate in the cavity or spacer 160. According to one embodiment of the present invention, the suspension portion 104 may include a piezoelectric material layer 106, a first finger electrode 110, a second finger electrode 120, a first floating electrode 116, a second floating electrode 126, and a dielectric layer (not shown). In the present invention, the technical term “floating electrode” refers to an electrode that is electrically insulated or not electrically connected to the first finger electrode 110 and the second finger electrode 120 . Therefore, electron flow or current cannot be directly transmitted from the first finger electrode 110 or the second finger electrode 120 to the floating electrode.

[0083] The piezoelectric material layer 106 may be a thin flat plate, for example, having a length or width of approximately 10 μm to 500 μm and a thickness of approximately 0.1 μm to 2 μm. The top side of the piezoelectric material layer 106 may be used to support the first finger electrodes 110, the second finger electrodes 120, the first floating electrode 116, and the second floating electrode 126.

[0084] A dielectric layer (not shown) may be disposed on the piezoelectric material layer 106 such that the dielectric layer covers the first finger electrodes 110, the second finger electrodes 120, the first floating electrodes 116, and the second floating electrodes 126. The dielectric layer may have openings, such as a first opening O1 and a second opening O2 disposed on opposite sides of the suspension portion 104. According to one embodiment of the present invention, the first opening O1 may be a strip-shaped opening extending along a certain direction (e.g., the X direction) and disposed corresponding to two ends of each first floating electrode 116, with these ends being adjacent to the main portion 112. The second opening O2 may be a strip-shaped opening extending along the same direction (e.g., the X direction) and disposed corresponding to two ends of each second floating electrode 126, with these ends being adjacent to the second main portion 122.

[0085] According to one embodiment of the present invention, the first finger electrodes 110 and the second finger electrodes 120 are arranged in a finger-like pattern. The first finger electrodes 110 may include a first trunk 112 and a plurality of first branches 114 electrically connected to the first trunk 112, while the second finger electrodes 120 may include a second trunk 122 and a plurality of second branches 124 electrically connected to the second trunk 122. The first branches 114 of the first finger electrodes 110 and the second branches 124 of the second finger electrodes 120 may be parallel to each other, for example, extending along the Y-direction. The first branches 114 and the second branches 124 may be staggered along a certain direction (e.g., the X-direction). Regarding the first floating electrodes 116, a first gap G1 may exist between one end of each first floating electrode 116 and the first trunk 112, while a second gap G2 may exist between the other end of each first floating electrode 116 and the second finger electrode 120. The first gap G1 can be used to accommodate the first insulating region 118, such as a cavity, and each first insulating region 118 can at least partially overlap with the first opening O1 in the dielectric layer. Similarly, for the second floating electrodes 126, a first gap G1' can exist between one end of each second floating electrode 126 and the second trunk portion 122, while a second gap G2' can exist between the other end of each second floating electrode 126 and the first finger electrode 110. The first gap G1' can be used to accommodate the second insulating region 128, such as a cavity, and each second insulating region 128 can at least partially overlap with the second opening O2 in the dielectric layer.

[0086] One of the first finger electrodes 110 and the second finger electrodes 120 can be electrically connected to an electrical signal input terminal, while the other can be electrically connected to an electrical signal output terminal. Thus, the electrical signal input from the electrical signal input terminal to the Lamb wave resonator 100 can be filtered, allowing the desired electrical signal to be output from the Lamb wave resonator 100 to the electrical signal output terminal. According to one embodiment of the present invention, the width of each first branch portion 114 and the width of each second branch portion 124 can be 0.1 μm to 1.0 μm, but are not limited thereto.

[0087] According to one embodiment of the present invention, the first floating electrode 116 and the second floating electrode 126 may be disposed between a first branch 114 and a second branch 124 adjacent to the first branch 114. Furthermore, the first floating electrode 116 and the second floating electrode 126 may be disposed between two adjacent first branches 114 or between two adjacent second branches 124. Furthermore, each first floating electrode 116 and each second floating electrode 126 may form a pair between adjacent first branches 114 and second branches 124, between adjacent first branches 114, and between adjacent second branches 124.

[0088] In the present invention, reference to "adjacent first and second branches" or a substantially equivalent description means that no additional first branches or second branches exist between the first and second branches, but a floating electrode may exist. Reference to "two adjacent first branches" or a substantially equivalent description means that no additional first branches exist between the two first branches, but a second branch or floating electrode may exist. Reference to "two adjacent second branches" or a substantially equivalent description means that no additional second branches exist between the two second branches, but a first branch or floating electrode may exist. Reference to "two adjacent first floating electrodes" or a substantially equivalent description means that no additional first floating electrodes exist between the two first floating electrodes, but a first branch or second branch may exist. Reference to "two adjacent second floating electrodes" or a substantially equivalent description means that no additional second floating electrodes exist between the two second floating electrodes, but a first branch or second branch may exist. In the present invention, when referring to "adjacent first floating electrodes and second floating electrodes" or a substantially equivalent description, it means that there are no additional first floating electrodes and second floating electrodes between the first floating electrodes and the second floating electrodes, and no first branch portions and second branch portions exist.

[0089] Figure 2 An embodiment of the present invention is Figure 1 The cross-sectional view shown by the A-A' tangent line. Figure 2 As shown, the Lamb wave resonator 100 may include a substrate 140, such as a semiconductor substrate or an insulating substrate, so that the frame portion 102 and the suspension portion 104 may be disposed on the substrate 140. According to one embodiment of the present invention, at least a dielectric base layer 142, an optional seed layer 146, an optional bottom electrode 150, a piezoelectric material layer 152, a top electrode (e.g., the first finger electrode 110 and the second finger electrode 120), a floating electrode (e.g., the second floating electrode 126), a passivation layer 154, a dielectric layer 156, and conductive contact pads (e.g., the first contact pad 158-1 and the second contact pad 158-2) may be disposed on the substrate 140. In addition, a spacer 160 is disposed between the suspension portion 104 and the frame portion 102, and a cavity 144 is disposed below the suspension portion 104.

[0090] According to one embodiment of the present invention, the material of the dielectric base layer 142 can be different from the material of the substrate 140 and the seed layer 146. The dielectric base layer 142 located in the frame portion 102 can be thicker to secure the frame portion 102 to the substrate 140, while the dielectric base layer 142 located in the suspension portion 104 can be thinner to avoid affecting the resonance of the suspension portion 104. According to one embodiment of the present invention, the seed layer 146 can be, for example, SiO2, SiON, AlN, or AlScN, and can be disposed between the bottom electrode 150 and the dielectric base layer 142. The surface texture of the seed layer 146 can affect the crystallinity of the layers deposited thereon.

[0091] The top electrodes (e.g., the first finger electrodes 110 and the second finger electrodes 120) and the bottom electrodes 150 can be disposed on opposite sides of the piezoelectric material layer 152, such as the top and bottom sides, respectively. The floating electrode (e.g., the second floating electrode 126) can be located on the same side as the top electrode. According to one embodiment of the present invention, the top electrode, the bottom electrode 150, and the floating electrode can be made of, but not limited to, a conductive material such as molybdenum (Mo), titanium (Ti), aluminum (Al), platinum (Pt), or alloys thereof. The first finger electrodes 110, the second finger electrodes 120, and the bottom electrodes 150 can each be electrically connected to a corresponding conductive contact pad, such as a first contact pad 158-1 and a second contact pad 158-2, so that the first finger electrodes 110, the second finger electrodes 120, and the bottom electrodes 150 can be grounded or receive / transmit electrical signals. The piezoelectric material layer 152 may be, for example, a piezoelectric material composed of at least one of AlN, AlScN, PZT, ZnO, PVDF, and PMN-PT, but is not limited thereto.

[0092] The passivation layer 154 can be used to passivate and / or protect the underlying piezoelectric material layer 152, top electrode, and floating electrode. According to one embodiment of the present invention, the passivation layer 154 can be composed of at least one of SiO2, SiON, AlN, AlScN, PZT, ZnO, PVDF, and PMN-PT, but is not limited thereto. Furthermore, the passivation layer 154 can fill the gaps between the first finger electrodes 110 and the second finger electrodes 120. A dielectric layer 156 can cover the passivation layer 154, and a first opening O1 and a second opening O2 are defined in the dielectric layer 156. According to one embodiment of the present invention, a second insulating region 128 can be provided below the bottom surface of the second opening O2, such as a cavity filled with air or containing a small amount of metal oxide or nitride. A thin passivation layer 154 can be present between the second opening O2 and the second insulating region 128.

[0093] Figure 3 An embodiment of the present invention is Figure 1 The cross-sectional view shown by the BB' tangent line. Figure 3 As shown, the thickness T1 of the piezoelectric material layer 152 may be greater than the thickness T2 of the passivation layer 154, or greater than the combined thickness T3 of the passivation layer 154 and the dielectric layer 156. According to one embodiment of the present invention, the passivation layer 154 may fill the gaps between the first branches 114 and may cover the top surfaces of the first branches 114 and the first insulating region 118. The first opening O1 in the dielectric layer 156 may expose the top surface of the passivation layer 154. According to one embodiment of the present invention, a pair of first insulating regions 118 may be provided between two adjacent first branches 114, such as cavities filled with air or containing a small amount of metal oxide or nitride. Since the first insulating regions 118 may be formed by laser ablation of a portion of the first branches 114, the width W1' of the first insulating regions 118 may be approximately equal to the width W1 of the first branches 114. Furthermore, the distance between the first insulating region 118 and the first branch portion 114 may be a first distance L1 and a second distance L2, and the distance between two adjacent first branch portions 114 may be a third distance L3. The first distance L1, the second distance L2, and the third distance L3 are an arithmetic progression, but are not limited thereto. According to one embodiment of the present invention, the Lamb wave wavelength λ of the Lamb wave resonator 100 is substantially equal to the distance (third distance L3) between two adjacent first branch portions 114.

[0094] Figure 4 An embodiment of the present invention is Figure 1 The cross-sectional view shown by the C-C' tangent line. Figure 4 As shown, according to one embodiment of the present invention, the passivation layer 154 can fill the gaps between the first branch portion 114, the second branch portion 124, the first floating electrode 116 and the second floating electrode 126, and can cover the top surface of the first branch portion 114, the top surface of the second branch portion 124, the top surface of the first floating electrode 116 and the top surface of the second floating electrode 126.

[0095] According to one embodiment of the present invention, the number of first floating electrodes 116 between two adjacent first branches 114 may be an even number (i.e., 2n, where n is a positive integer), such as, but not limited to, 2, 4, 6, or 8. Furthermore, the width W1, or average width, of each first floating electrode 116 may be approximately equal to the width W1′, or average width, of each first branch 114. Adjacent first floating electrodes 116 and first branches 114 may have a pitch, such as a first pitch P1, between each adjacent first floating electrode 116 and first branch 114, while adjacent first branches 114 may have a pitch, such as a second pitch P2, between each adjacent first branch 114. The first pitch P1 and the second pitch P2 may satisfy a specific ratio, such as 1:2n+1, where n is a positive integer and 2n is the total number of first floating electrodes 116 and second floating electrodes 126. Furthermore, a first floating electrode 116 may be disposed on both sides of each second branch portion 124, and adjacent first floating electrodes 116 may have a pitch, such as a third pitch P3, such that the third pitch P3 and the second pitch P2 (i.e., the pitch between two adjacent first branches 114) may satisfy a specific ratio, such as 1:2n+1, where n is a positive integer.

[0096] According to one embodiment of the present invention, the number of second floating electrodes 126 between two adjacent first branches 114 may be an even number (i.e., 2n, where n is a positive integer), such as, but not limited to, 2, 4, 6, or 8. Furthermore, the width W2, or average width, of each second floating electrode 126 may be approximately equal to the width W2', or average width, of each second branch 124. Adjacent second floating electrodes 126 and first branches 114 may have a pitch, such as a fourth pitch P4, between them, while adjacent first branches 114 and second branches 124 may have a pitch, such as a fifth pitch P5, between them. The fourth pitch P4 and the fifth pitch P5 may satisfy a specific ratio, such as 1:2n+1, where n is a positive integer.

[0097] According to the above embodiment, a relatively thin passivation layer 154 is present between the openings (e.g., the first opening O1 and the second opening O2) in the dielectric layer 156 and the underlying insulating segments (e.g., the first insulating region 118 and the second insulating region 128). However, the present invention is not limited thereto. According to other embodiments of the present invention, no passivation layer 154 may be present between the openings in the dielectric layer 156 and the underlying insulating segments. Figure 5 A variation of the present invention is as follows Figure 1 The cross-sectional view shown by the A-A' tangent line is shown in FIG. Figure 6 A variation of the present invention is as follows Figure 1The cross-sectional view shown by the BB' tangent line. Figure 5 As shown, a second insulating region 128 may be provided correspondingly below the bottom surface of the second opening O2 of the Lamb wave resonator 200, such as a cavity, and the cavity may be connected to the bottom surface of the second opening O2. Figure 5 In the embodiment shown, there is no passivation layer 154 between the second opening O2 and the second insulating region 128. Figure 6 As shown, the cavity 130 can be formed in the passivation layer 154, exposing a portion of the piezoelectric material layer 152, and the cavity 130 can be connected to the bottom surface of the first opening O1. Figure 6 In the illustrated embodiment, the first insulating region 118 can be considered as part of the cavity 130 .

[0098] For the Lamb wave resonators 100 and 200 described in the above embodiments, the first floating electrode 116 and the second floating electrode 126 can be obtained by truncating the first branch portion 114 and the second branch portion 124 at a specific interval. By truncating the first branch portion 114 and the second branch portion 124 at a specific interval, the resonant frequency of the Lamb wave resonator 100 can be lowered, for example, the resonant frequency of the S0 mode can be lowered, such that the relationship between the resonant frequency of the S0 mode after truncation and the resonant frequency of the S0 mode before truncation satisfies approximately 1:2n+1, where n is a positive integer.

[0099] Figure 7 is the resonant frequency change of the Lamb wave resonator before and after the branch portion is cut off in one embodiment of the present invention. Figure 7 As shown, for similar Figure 1For the Lamb wave resonator 100 shown, when only a pair of first floating electrodes 116 and second floating electrodes 126 exists between each adjacent first branch 114 and second branch 124, the resonant frequency of the S0 mode of the Lamb wave resonator 100 decreases by a frequency difference Δf from the initial resonant frequency before truncation (e.g., approximately 4.5 GHz) to a final resonant frequency after truncation (e.g., approximately 1.5 GHz). Therefore, the ratio of the final resonant frequency to the initial resonant frequency is approximately 1:3, satisfying the proportional relationship 1:2n+1, where n is a positive integer. Furthermore, according to one embodiment of the present invention, when the Lamb wave resonator is provided with a bottom electrode (e.g., bottom electrode 150), the effective piezoelectric coupling coefficient (Keff2) of the Lamb wave resonator can be maintained greater than 1.0%, for example, greater than 1.5%, regardless of the bottom electrode's top-view layout (planar or finger-shaped) or electrical connection (floating or grounded). In other words, for Lamb wave resonators with varying numbers of floating electrodes and branches, the presence of a bottom electrode allows the effective piezoelectric coupling coefficient (Keff2) to remain above a certain value. Furthermore, the measured values ​​of the initial and final resonant frequencies of the Lamb wave resonators described above are within a certain tolerance, for example, within ±20%.

[0100] In addition to the above-described embodiments, the present invention also includes other variations of the Lamb wave resonator. To simplify the description, the following description focuses on the differences between the various embodiments and does not reiterate the similarities. Furthermore, identical components in the various embodiments of the present invention are labeled with the same reference numerals to facilitate cross-reference between the various embodiments.

[0101] Figure 8 FIG. 1 is a top view of a Lamb wave resonator according to a variation of the present invention. Figure 8 As shown, Figure 8 The Lamb wave resonator 300 shown is similar to Figure 1 The Lamb wave resonator 100 shown in FIG. 1 is different in that the first opening O1 is not a single strip-shaped opening, but rather a plurality of geometric openings separated from each other, such as a plurality of openings intermittently distributed along the X-direction. Each first opening O1 is disposed corresponding to one end of the first floating electrode 116 and at least partially overlaps with each first insulating region 118.

[0102] Figure 9 FIG. 1 is a top view of a Lamb wave resonator according to a variation of the present invention. Figure 9 As shown, Figure 9 The Lamb wave resonator 400 shown is similar to Figure 1The Lamb wave resonator 100 shown in FIG. A major difference lies in the fact that two pairs of first floating electrodes 116 and second floating electrodes 126 are disposed between each adjacent first branch 114 and second branch 124. In other words, before the first floating electrodes 116 and second floating electrodes 126 are formed, the resonant frequency of the S0 mode of the Lamb wave resonator 400 can be resonant frequency f1, while after the first floating electrodes 116 and second floating electrodes 126 are formed, the resonant frequency of the S0 mode of the Lamb wave resonator 400 can be resonant frequency f2. The ratio between resonant frequencies f1 and f2 can be approximately 5:1, satisfying the proportional relationship 2n+1:1, where n is a positive integer.

[0103] Figure 10 A variation of the present invention is as follows Figure 1 The cross-sectional view shown by the A-A' tangent line. Figure 10 As shown, Figure 10 The Lamb wave resonator 500 shown is similar to Figure 2 The Lamb wave resonator 100 shown in FIG. 1 primarily differs in that a semiconductor device, such as a switch or amplifier, may be disposed in the substrate 140, and a conductive line 504 and a dielectric layer 506 electrically connected to the semiconductor device are disposed between the substrate 140 and the dielectric base layer 142. The bottom of the second contact pad 158-2 may penetrate the dielectric base layer 142 and be electrically connected to the conductive line 504. According to one embodiment of the present invention, an electronic signal generated by the semiconductor device in the substrate 140 may be transmitted sequentially through the conductive line 504 and the second contact pad 158-2 to the first finger electrode 110 or the second finger electrode 120. Figure 11 A variation of the present invention is as follows Figure 1 The cross-sectional view shown by the A-A' tangent line. Figure 11 As shown, Figure 11 The Lamb wave resonator 600 shown is similar to Figure 2 The main difference of the Lamb wave resonator 100 shown is that a cavity 606 is provided in the substrate 140, and a thin dielectric layer 604 is disposed between the substrate 140 and the seed layer 146. According to one embodiment of the present invention, when the Lamb wave resonator 600 resonates, the suspension 104 can oscillate in the cavity 606 in the substrate 140.

[0104] Figure 12 A variation of the present invention is as follows Figure 1 The cross-sectional view shown by the A-A' tangent line. Figure 12 As shown, Figure 12 The Lamb wave resonator 700 shown is similar to Figure 11The Lamb wave resonator 600 shown is different in that the substrate 140 is a semiconductor-on-insulator substrate, such as a silicon-on-insulator substrate, on which a first semiconductor layer 602 , an insulating layer 608 and a second semiconductor layer 610 are stacked in sequence from bottom to top.

[0105] To enable those skilled in the art to implement the present invention, the following further describes a method for fabricating a Lamb wave resonator. Furthermore, because Lamb wave resonators can be fabricated using a standard CMOS process, related electronic components, such as field-effect transistors, amplifiers, and integrated circuits, can also be fabricated using the same CMOS process on the same substrate as the Lamb wave resonator.

[0106] Figure 13 FIG. 1 is a top view schematic diagram of a Lamb wave resonator according to an embodiment of the present invention. Figure 13 As shown, the first finger electrode 110 and the second finger electrode 120 in the Lamb wave resonator 800 can be arranged on the top side of the piezoelectric material layer 106, and the first opening O1 and the second opening O2 can be strip-shaped openings and are respectively arranged at one end of the second branch portion 124 and the first branch portion 114.

[0107] Figure 14 An embodiment of the present invention is Figure 13 The cross-sectional view shown by the A-A' tangent line. Figure 14 As shown, the Lamb wave resonator 800 may include a substrate 140, with a dielectric base layer 142 and a sacrificial layer 132 disposed between the substrate 140 and a seed layer 146. The dielectric base layer 142 and the sacrificial layer 132 are made of different materials, and thus, during a subsequent etching process, the etchant may produce different etching rates for the dielectric base layer 142 and the sacrificial layer 132. According to one embodiment of the present invention, at this point in the process, the passivation layer 154 may completely cover the top electrodes (e.g., the first finger electrodes 110 and the second finger electrodes 120) and fill the gaps between the first finger electrodes 110 and the second finger electrodes 120.

[0108] Figure 15 FIG. 1 is a cross-sectional view of an embodiment of the present invention after the sacrificial layer is removed. Figure 15 As shown, at least one spacer 160 can be formed penetrating the piezoelectric material layer 150, and an etchant can be provided to the sacrificial layer 132 through the spacer 160 to remove the sacrificial layer 132, thereby forming a cavity 144 below the piezoelectric material layer 152. Therefore, after removing the sacrificial layer 132, the Lamb wave resonator 800 can include a frame portion 102 and a suspension portion 104, wherein the frame portion 102 can surround the periphery of the suspension portion 104.

[0109] Subsequently, a laser ablation process may be further performed to focus laser energy on a portion of the first branch portion 114 directly below the first opening O1 and a portion of the second branch portion 124 below the second opening O2, so that a portion of the first branch portion 114 and a portion of the second branch portion 124 may be ablated and vaporized, thereby forming a first insulating region 118 and a second insulating region 128 in the corresponding regions, and simultaneously forming a first floating electrode 116 and a second floating electrode 126, thereby obtaining the following: Figures 2 to 3 According to an embodiment of the present invention, since the thickness of the dielectric layer 156 and the passivation layer 154 affects the focusing depth of the laser energy, the first opening O1 and the second opening O2 are formed in the dielectric layer 156 or the passivation layer 154 to facilitate the transmission of the laser energy to a predetermined depth.

[0110] According to a variation of the present invention, the method of forming the first insulating region 118 and the second insulating region 128 is not limited to laser ablation, but may also be to use photolithography and etching processes to remove a portion of the first branch portion 114 and a portion of the second branch portion 124 to form the first insulating region 118 and the second insulating region 128. Figure 16 This is a cross-sectional view of a modified embodiment of the present invention after removing part of the second branch portion. Figure 15 After the structure shown, Figure 16 As shown, a photolithography process can be used to form a patterned photoresist 170 having a plurality of openings 172. Subsequently, an etching process can be performed to remove the passivation layer 154, the first branch portion 114, and the second branch portion 124 exposed at the bottom surface of the openings 172, thereby forming insulating regions 118 and 128, such as the cavity 130, below the openings 172. Upon completion of this etching process, the desired floating electrodes 116 and 126 can be obtained.

[0111] The patterned photoresist can be subsequently removed, and another photolithography and etching process can be used to form at least one gap penetrating the piezoelectric material layer 152. Then, an etchant is provided to the sacrificial layer 132 through the gap to etch away the sacrificial layer 132, thereby forming a cavity below the piezoelectric material layer 152, and obtaining the following: Figures 2 to 3 The structure shown in the embodiment.

[0112] According to another variation of the present invention, the time point of performing the photolithography and etching process to form the first insulating region 118 and the second insulating region 128 is not limited to after the dielectric layer 156 is deposited, but may be before the dielectric layer 156 is deposited, or before the passivation layer 154 is deposited. According to one embodiment of the present invention, after forming the first finger electrode 110 and the second finger electrode 120, but before depositing the passivation layer 154 or the dielectric layer 156, a photolithography process may be performed to form a patterned photoresist on the first finger electrode 110 and the second finger electrode 120, and define the area where the first finger electrode 110 and the second finger electrode 120 will be cut off. Thereafter, an etching process may be performed to cut off part of the first finger electrode 110 and the second finger electrode 120, and obtain the desired floating electrodes 116 and 126. At this time, the top-view distribution of the floating electrodes 116 and 126 may be similar to the following. Figure 1 、 Figure 8 and Figure 9 The structure shown in the embodiment is not limited thereto. Afterwards, a subsequent process for manufacturing the Lamb wave resonator may be performed, such as a process similar to that described in the above embodiment, to obtain the desired Lamb wave resonator.

[0113] According to the above embodiments, by truncating branches at specific spacings (e.g., a pair of first and second branches), the resonant frequency of a Lamb wave resonator can be lowered, for example, the resonant frequency of the S0 mode. Therefore, when fabricating a Lamb wave resonator with a different resonant frequency, there is no need to redesign the layout or spacing of the branches in the finger electrodes of the Lamb wave resonator. Instead, a specific mask pattern of the finger electrodes can be utilized, combined with a subsequent laser ablation process or photolithography and etching process, to truncate the branches at specific spacings, thereby achieving the effect of lowering the resonant frequency of the Lamb wave resonator.

[0114] The above is a further detailed description of the present invention in conjunction with specific preferred embodiments, and the specific implementation of the present invention should not be considered to be limited to these descriptions. Those skilled in the art will recognize that several equivalent substitutions or obvious variations can be made without departing from the scope of the present invention, and that any equivalent performance or application should be considered to fall within the scope of protection of the present invention.

Claims

1. A Lamb wave resonator, characterized in that: include: a piezoelectric material layer; a first finger-shaped electrode disposed on one side of the piezoelectric material layer, the first finger-shaped electrode comprising a first main portion and a plurality of first branch portions; a second finger electrode disposed on the one side of the piezoelectric material layer, the second finger electrode comprising a second main body and a plurality of second branches, wherein each of the first branches is parallel to each of the second branches and is arranged in a staggered manner; at least two floating electrodes, disposed between each of the first branch portions and each of the second branch portions; as well as At least two gaps are respectively provided at two ends of each of the floating electrodes; a dielectric layer covering the first finger-shaped electrode, the second finger-shaped electrode and the at least two floating electrodes; as well as At least two openings are disposed in the dielectric layer and corresponding to the gaps.

2. The Lamb wave resonator according to claim 1, wherein The width of each of the first branches is the same as the width of each of the floating electrodes.

3. The Lamb wave resonator according to claim 1, wherein The at least two floating electrodes include at least two first floating electrodes, each of the first floating electrodes is disposed between two adjacent ones of the plurality of first branches, and the number of the at least two floating electrodes is an even number 2n, where n is a positive integer.

4. The Lamb wave resonator according to claim 3, wherein The at least two floating electrodes further include at least one second floating electrode, and there is a spacing between adjacent first branches and the at least one second floating electrode, and there is another spacing between adjacent first branches and the second branches, and the ratio between the spacing and the another spacing is 1:2n+1, where n is a positive integer.

5. The Lamb wave resonator according to claim 1, wherein Also includes: At least one insulating region is disposed at at least one end of each of the floating electrodes and overlaps at least one of the at least two gaps.

6. The Lamb wave resonator according to claim 5, wherein Also includes: A passivation layer covers the at least one insulating region, wherein a portion of the passivation layer is exposed in each of the openings.

7. The Lamb wave resonator according to claim 5, wherein The at least one insulating region is a cavity.

8. The Lamb wave resonator according to claim 5, wherein The at least two floating electrodes include at least two first floating electrodes, and the at least one insulating region is disposed between each of the first floating electrodes and the first trunk portion.

9. The Lamb wave resonator according to claim 1, wherein The at least two floating electrodes include: at least one first floating electrode; and At least one second floating electrode is disposed between each of the first branch portions and each of the second branch portions and is adjacent to the at least one first floating electrode.

10. The Lamb wave resonator according to claim 9, wherein The width of each of the second branches is the same as the width of the at least one second floating electrode.

11. The Lamb wave resonator according to claim 9, wherein The at least one second floating electrode is disposed between two adjacent ones of the plurality of first branches, and the number of the at least one second floating electrode is an even number 2n, where n is a positive integer.

12. The Lamb wave resonator according to claim 9, wherein No first branch portion or any second branch portion is disposed between the at least one first floating electrode and the at least one second floating electrode adjacent to the at least one first floating electrode.

13. The Lamb wave resonator according to claim 9, wherein The at least one first floating electrode and the at least one second floating electrode appear in pairs.

14. The Lamb wave resonator according to claim 9, wherein Also includes: a dielectric layer covering the at least two floating electrodes; at least one first opening disposed in the dielectric layer and corresponding to one end of the at least one first floating electrode; and At least one second opening is disposed in the dielectric layer and is disposed corresponding to one end of the at least one second floating electrode, wherein the one end of the second floating electrode is away from the one end of the first floating electrode.

15. The Lamb wave resonator according to claim 1, wherein The invention also includes a bottom electrode, which is arranged on the other side of the piezoelectric material layer.

16. The Lamb wave resonator according to claim 1, wherein: The plurality of first branch portions include at least two first branch portions, which are disposed on one side of the piezoelectric material layer; The plurality of second branches include at least one second branch disposed on the one side of the piezoelectric material layer and between the plurality of first branches; and The at least two floating electrodes include at least two first floating electrodes disposed on the one side of the piezoelectric material layer, wherein the at least two first floating electrodes are respectively disposed on both sides of the at least one second branch portion and disposed between the plurality of first branch portions; There is a first distance between adjacent first floating electrodes and first branches, and a second distance between adjacent first branches. The ratio of the first distance to the second distance is 1:2n+1, where n is a positive integer.

17. The Lamb wave resonator according to claim 1, wherein The plurality of first branches are electrically connected to an electrical signal input terminal, and the plurality of second branches are electrically connected to an electrical signal output terminal.

18. The Lamb wave resonator according to claim 1, wherein The at least two floating electrodes are electrically insulated from the first branch portions and the second branch portions.

19. A method for manufacturing a Lamb wave resonator, characterized in that: include: providing a piezoelectric material layer; forming a first finger-shaped electrode on one side of the piezoelectric material layer, wherein the first finger-shaped electrode includes a plurality of first branches; forming a dielectric layer covering the piezoelectric material layer and the plurality of first branches; forming at least one first opening in the dielectric layer, wherein the at least one first opening overlaps a portion of the plurality of first branches; as well as The portion of the first branches overlapping the at least one first opening is removed to form at least two first floating electrodes.

20. The method for manufacturing a Lamb wave resonator according to claim 19, wherein: There is a first distance between adjacent first floating electrodes and first branches, and a second distance between adjacent first branches. The ratio of the first distance to the second distance is 1:2n+1, where n is a positive integer.

21. The method for manufacturing a Lamb wave resonator according to claim 19, wherein: When forming the at least two first floating electrodes, at least two first insulating regions are formed simultaneously, and each of the first insulating regions is respectively arranged at one end of each of the first floating electrodes.

22. The method for manufacturing a Lamb wave resonator according to claim 19, wherein: When forming the at least two first floating electrodes, laser ablation is used to ablate the partial regions of the plurality of first branches overlapping the at least one first opening.

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