Bulk Acoustic Wave Resonator

Abstract

The present disclosure provides a bulk acoustic wave resonator, which includes: a substrate; a first electrode, wherein a cavity is formed between the substrate and the first electrode; a piezoelectric layer, which is disposed on the first electrode and overlaps at least a portion of the first electrode; a second electrode, which is disposed on the piezoelectric layer and overlaps at least a portion of the piezoelectric layer; a passivation layer, which has at least a portion disposed on the second electrode and overlaps at least a portion of the second electrode; and a lower frame, which is spaced apart from the substrate, and a portion of the cavity is disposed between the lower frame and the substrate. Either of the second electrode and the passivation layer includes a protrusion having a first thickness and an extension having a second thickness smaller than the first thickness, and an inner end of the lower frame and an end of the protrusion are horizontally spaced apart.

Description

[0001] This application claims the benefit of priority from Korean Patent Application No. 10-2020-0131876 filed on October 13, 2020, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein in its entirety for all purposes by reference. Technical Field

[0002] The present disclosure relates to a bulk acoustic wave resonator. Background Art

[0003] Bulk acoustic wave (BAW) filters are core components in front-end modules of smart phones, tablet personal computers (PCs), etc. that allow signals with desired frequency bands in radio frequency (RF) signals to pass and block signals with undesired frequency bands in RF signals, and the demand for bulk acoustic wave (BAW) filters has increased in accordance with the growth of the mobile and base station communication markets.

[0004] In addition, the BAW filter may include a plurality of BAW resonators, and if the Q performance of the BAW resonator is good, the characteristic (roll-off characteristic) of being able to select only a desired frequency band in the BAW filter is improved. In addition, the insertion loss and attenuation performance in the BAW filter are improved.

[0005] To this end, it is necessary to form a frame around the resonator and control the width and thickness of the frame to drive a resonant waveform generated in the resonator in a piston mode.

[0006] The above information is presented only as background information to help understand the present disclosure. The above description should not be interpreted as these contents belonging to the prior art of the present disclosure. Summary of the invention

[0007] This summary is provided to introduce selected concepts in a simplified form that are further described below in the detailed description. This summary is neither intended to identify key features or essential features of the claimed subject matter nor to be used as an aid in determining the scope of the claimed subject matter.

[0008] In one general aspect, a bulk acoustic wave resonator includes: a substrate; a first electrode, wherein a cavity is formed between the substrate and the first electrode; a piezoelectric layer disposed on the first electrode and overlapping at least a portion of the first electrode; a second electrode disposed on the piezoelectric layer and overlapping at least a portion of the piezoelectric layer; a passivation layer having at least a portion disposed on the second electrode and overlapping at least a portion of the second electrode; and a lower frame spaced apart from the substrate, with a portion of the cavity disposed between the lower frame and the substrate, wherein either the second electrode and the passivation layer includes a protrusion having a first thickness and an extension having a second thickness smaller than the first thickness, and wherein an inner end of the lower frame and an end of the protrusion are spaced apart in a horizontal direction.

[0009] At least a portion of the extension may overlap the lower frame.

[0010] The lower frame may be formed using the same material as that of the first electrode.

[0011] The lower frame may be disposed under the first electrode, and may be formed using a material different from that of the first electrode.

[0012] The lower frame may be formed using an insulating material having a density lower than that of the first electrode.

[0013] The passivation layer may include the protrusion and the extension, and the passivation layer may be formed using an insulating material having a density lower than that of the first electrode.

[0014] The BAW resonator may further include an additional layer disposed between the lower frame and the first electrode.

[0015] The second electrode may include a frame part having at least a portion overlapped with the lower frame, and a thickness of the frame part is greater than a thickness of other portions of the second electrode.

[0016] An inner end of the frame portion and an inner end of the lower frame may be spaced apart in the horizontal direction.

[0017] The BAW resonator may further include an anti-etching layer disposed to surround the cavity.

[0018] The BAW resonator may further include a sacrificial layer disposed outside the anti-etching layer.

[0019] The BAW resonator may further include an insertion layer disposed between the first electrode and the piezoelectric layer.

[0020] In another general aspect, a bulk acoustic wave resonator includes: a substrate; a first electrode, wherein a cavity is disposed between the substrate and the first electrode; a piezoelectric layer disposed on the first electrode and overlapping at least a portion of the first electrode; a second electrode disposed on the piezoelectric layer and overlapping at least a portion of the piezoelectric layer; a passivation layer having at least a portion disposed on the second electrode and overlapping at least a portion of the second electrode; and a lower frame spaced apart from the substrate, and a portion of the cavity is disposed between the lower frame and the substrate, wherein either the second electrode or the passivation layer includes a protrusion having a first thickness and an extension having a second thickness smaller than the first thickness, and wherein an effective region, a first region, and a second region are continuously disposed, in the effective region the protrusion, the piezoelectric layer, and the first electrode all overlap, the first region is disposed between an end of the protrusion and an inner end of the lower frame, and the second region is disposed outside the first region and in the second region the extension and the lower frame overlap.

[0021] The frequencies f0, f1, and f2 in the effective region, the first region, and the second region may have a relationship of f2 < f0 < f1.

[0022] When the lateral wave numbers in the effective region, the first region, and the second region are β0, β1, and β2 respectively, at the resonant frequency, β0 may be 0, β1 may be a real value, and β2 may be an imaginary value.

[0023] When the acoustic impedances in the effective region and the second region are z0 and z2 respectively, the value of z2 may be greater than the value of z0.

[0024] In another general aspect, a bulk acoustic wave resonator includes: a substrate; a first electrode disposed on the substrate and spaced apart from the substrate by a cavity; a piezoelectric layer disposed on the first electrode; a second electrode disposed on the piezoelectric layer; an upper layer disposed on the second electrode; and a lower frame spaced apart from the substrate, and a portion of the cavity is disposed between the lower frame and the substrate, wherein the upper layer includes a protrusion and an extension, the protrusion has a first thickness, the extension has a second thickness smaller than the first thickness, and wherein an inner end of the lower frame and an end of the protrusion are spaced apart in a horizontal direction.

[0025] The upper layer may include a passivation layer.

[0026] Other features and aspects will be apparent from the following detailed description, the drawings, and the claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 is a schematic configuration diagram showing a main configuration of a bulk acoustic wave resonator according to an example embodiment in the present disclosure.

[0028] Figure 2 is a graph showing values ​​of S11 of a BAW resonator according to an example embodiment in the present disclosure and a resonator according to the related art.

[0029] Figure 3 is a diagram illustrating a difference in thickness between a protruding portion and an extending portion of a second electrode and a width of a first region.

[0030] Figure 4 is a graph showing that when the thickness difference between the protruding portion and the extending portion of the second electrode is A graph showing the value of S11 according to the width of the first region R in Å (angstroms).

[0031] Figure 5 is a graph showing that when the thickness difference between the protruding portion and the extending portion of the second electrode is Graph showing the value of S11 according to the width of the first region R.

[0032] Figure 6 is a graph showing that when the thickness difference between the protruding portion and the extending portion of the second electrode is Graph showing the value of S11 according to the width of the first region.

[0033] Figure 7 is a schematic configuration diagram showing a main configuration of a bulk acoustic wave resonator according to an example embodiment in the present disclosure.

[0034] Figure 8 is a schematic configuration diagram showing a main configuration of a bulk acoustic wave resonator according to an example embodiment in the present disclosure.

[0035] Fig. 9 is a diagram illustrating a difference in thickness between a protruding portion and an extending portion of a passivation layer and a width of a first region.

[0036] Fig.10 It shows that when the thickness difference between the protrusion and the extension of the passivation layer is Graph showing the value of S11 according to the width of the first region R.

[0037] Fig.11 It shows that when the thickness difference between the protrusion and the extension of the passivation layer is Graph showing the value of S11 according to the width of the first region R.

[0038] Fig.12 It shows that when the thickness difference between the protrusion and the extension of the passivation layer is Graph showing the value of S11 according to the width of the first region.

[0039] Figures 13 to 17 is a schematic configuration diagram showing a main configuration of a bulk acoustic wave resonator according to an example embodiment in the present disclosure.

[0040] Fig.18 is a schematic cross-sectional view illustrating a bulk acoustic wave resonator according to an example embodiment in the present disclosure.

[0041] Fig.19 It is shown Fig.18 An enlarged view of part A of FIG.

[0042] Throughout the drawings and detailed description, like reference numerals denote like elements. The drawings may not be drawn to scale, and the relative sizes, proportions, and depictions of elements in the drawings may be exaggerated for clarity, illustration, and convenience. DETAILED DESCRIPTION

[0043] Hereinafter, although example embodiments of the present disclosure will be described in detail with reference to the accompanying drawings, it should be noted that the examples are not limited thereto.

[0044] The following detailed description is provided to help the reader gain a comprehensive understanding of the methods, devices, and / or systems described herein. However, various changes, modifications, and equivalents of the methods, devices, and / or systems described herein will be apparent upon understanding the present disclosure. For example, the order of operations described herein is merely an example and is not limited to the order set forth herein, but changes may be made that will be apparent upon understanding the present disclosure, except for operations that must occur in a particular order. In addition, descriptions of functions and configurations known in the art may be omitted for clarity and brevity.

[0045] The features described herein may be implemented in different forms and should not be construed as being limited to the examples described herein. Rather, the examples described herein have been provided merely to illustrate some of the many possible ways to implement the methods, devices, and / or systems described herein that will be apparent after understanding the present disclosure.

[0046] Here, it should be noted that the use of the term "may" with respect to examples or embodiments (e.g., with respect to what an example or embodiment may include or implement) means that there is at least one example or embodiment that includes or implements such features, and is not limited to all examples or embodiments including or implementing such features.

[0047] Throughout the specification, when an element (such as a layer, region, or substrate) is described as being "on," "connected to," or "bonded to" another element, the element may be directly "on," "connected to," or "bonded to" another element, or one or more other elements may be present between them. In contrast, when an element is described as being "directly on," "directly connected to," or "directly bonded to" another element, there are no other elements present between them. As used herein, "a portion" of an element may include the entire element or a portion of the entire element that is smaller than the entire element.

[0048] As used herein, the term “and / or” includes any one or any combination of any two or more of the associated listed items; similarly, “at least one of” includes any one or any combination of any two or more of the associated listed items.

[0049] Although terms such as "first", "second", and "third" may be used herein to describe various members, components, regions, layers, or portions, these members, components, regions, layers, or portions are not limited by these terms. Rather, these terms are only used to distinguish one member, component, region, layer, or portion from another member, component, region, layer, or portion. Therefore, without departing from the teachings of the examples described herein, the first member, first component, first region, first layer, or first portion referred to in the examples may also be referred to as the second member, second component, second region, second layer, or second portion.

[0050] For ease of description, spatially relative terms such as "above", "above", "below", "below", etc. may be used herein to describe the relationship of one element to another element as shown in the drawings. Such spatially relative terms are intended to include different orientations of the device in use or operation in addition to the orientations depicted in the drawings. For example, if the device in the drawings is turned over, the element described as being "above" or "above" relative to another element will then be "below" or "below" relative to the other element. Therefore, the term "above" includes both "above" and "below" orientations depending on the spatial orientation of the device. The device may also be positioned in other ways (e.g., rotated 90 degrees or in other orientations), and the spatially relative terms used herein will be interpreted accordingly.

[0051] The terms used herein are only used to describe various examples and are not used to limit the present disclosure. Unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. The terms "comprise", "include" and "have" list the existence of the stated features, quantities, operations, components, elements and / or their combinations, but do not exclude the existence or addition of one or more other features, quantities, operations, components, elements and / or their combinations.

[0052] Due to manufacturing techniques and / or tolerances, the shapes shown in the drawings may vary. Therefore, the examples described herein are not limited to the specific shapes shown in the drawings but include changes in shapes that occur during manufacturing.

[0053] The features of the examples described herein may be combined in various ways that will be apparent after understanding the present disclosure. In addition, although the examples described herein have a variety of configurations, other configurations that will be apparent after understanding the present disclosure are possible.

[0054] One aspect of the present disclosure may provide a bulk acoustic wave resonator that may reduce the occurrence of parasitic noise and notches.

[0055] Figure 1 is a schematic configuration diagram showing a partial configuration of a bulk acoustic wave resonator according to an example embodiment in the present disclosure.

[0056] Reference Figure 1 The BAW resonator 100 may include, for example, a substrate 110 , a first electrode 120 , a piezoelectric layer 130 , and a second electrode 140 .

[0057] The substrate 110 may be a silicon substrate. For example, a silicon wafer or a silicon-on-insulator (SOI) type substrate may be used as the substrate 110 .

[0058] The insulating layer 112 may be formed on the upper surface of the substrate 110 and may electrically isolate components disposed on the insulating layer 112 from the substrate 110. In addition, the insulating layer 112 may prevent the substrate 110 from being etched by an etching gas when forming the cavity C in a process of manufacturing a BAW resonator.

[0059] In this case, the insulating layer 112 can be formed using at least one of silicon dioxide (SiO2), silicon nitride (Si3N4), aluminum oxide (Al2O3) and aluminum nitride (AlN), and can be formed by any one of a chemical vapor deposition process, a radio frequency (RF) magnetron sputtering process and an evaporation process.

[0060] The cavity C may be disposed between the first electrode 120 and the substrate 110. As an example, the first electrode 120 may be used as any one of an input electrode inputting an electrical signal such as a radio frequency (RF) signal and an output electrode outputting an electrical signal such as a radio frequency (RF) signal.

[0061] In addition, the first electrode 120 may be formed using, for example, a conductive material such as molybdenum (Mo) or an alloy thereof. However, the first electrode 120 is not limited thereto and may be formed using a conductive material such as ruthenium (Ru), tungsten (W), iridium (Ir), platinum (Pt), copper (Cu), titanium (Ti), tantalum (Ta), nickel (Ni) or chromium (Cr) or an alloy thereof.

[0062] In addition, a lower frame 150 may be disposed at the edge of the first electrode 120. The lower frame 150 may be disposed in the cavity C, and may be integrally formed with the first electrode 120 or may be formed using the same material as that of the first electrode 120.

[0063] The piezoelectric layer 130 may overlap at least a portion of the first electrode 120. In addition, the piezoelectric layer 130 may be a portion causing a piezoelectric effect that converts electrical energy into mechanical energy in the form of elastic waves, and may be formed using one of aluminum nitride (AlN), zinc oxide (ZnO), and lead zirconate titanate (PZT, PbZrTiO3). In particular, in the case where the piezoelectric layer 130 is formed using aluminum nitride (AlN), the piezoelectric layer 130 may further include a rare earth metal. As an example, the rare earth metal may include at least one of scandium (Sc), erbium (Er), yttrium (Y), and lanthanum (La). In addition, as an example, the piezoelectric layer 130 may also include at least one of titanium (Ti), zirconium (Zr), hafnium (Hf), tantalum (Ta), and niobium (Nb) as transition metals. In addition, the piezoelectric layer 130 may also include magnesium (Mg) (divalent metal).

[0064] The second electrode 140 may overlap at least a portion of the piezoelectric layer 130. In addition, the second electrode 140 may be used as any one of an input electrode for inputting an electrical signal such as a radio frequency (RF) signal and an output electrode for outputting an electrical signal such as a radio frequency (RF) signal. That is, in the case where the first electrode 120 is used as an input electrode, the second electrode 140 may be used as an output electrode, and in the case where the first electrode 120 is used as an output electrode, the second electrode 140 may be used as an input electrode.

[0065] The second electrode 140 may be formed using, for example, a conductive material such as molybdenum (Mo) or an alloy thereof. However, the second electrode 140 is not limited thereto and may be formed using a conductive material such as ruthenium (Ru), tungsten (W), iridium (Ir), platinum (Pt), copper (Cu), titanium (Ti), tantalum (Ta), nickel (Ni), or chromium (Cr), or an alloy thereof.

[0066] In addition, the second electrode 140 may include a protrusion 142 having a first thickness t1 and an extension 144 having a thickness less than that of the protrusion 142. The thickness of the extension 144 is defined as a second thickness t2.

[0067] In addition, a region where the protrusion 142, the piezoelectric layer 130, and the first electrode 120 are all stacked is defined as an effective region S, a region between the end of the protrusion 142 and the inner end of the lower frame 150 is defined as a first region R, and a region where the extension 144 and the lower frame 150 are stacked is defined as a second region U.

[0068] In addition, the first region R may be disposed outside the effective region S, and the second region U may be disposed outside the first region R. In addition, the effective region S, the first region R, and the second region U may be continuously disposed.

[0069] In addition, the frequencies in the effective region S, the first region R, and the second region U are respectively referred to as f0, f1, and f2, the transverse wave numbers in the effective region S, the first region R, and the second region U are respectively referred to as β0, β1, and β2, and the acoustic impedances in the effective region S, the first region R, and the second region U are respectively referred to as z0, z1, and z2.

[0070] In addition, the frequencies f0, f1, and f2 in the effective region S, the first region R, and the second region U may have a relationship of f2 < f0 < f1.

[0071] In addition, at the resonance frequency, β0 may be 0, β1 may be a real value, and β2 may be an imaginary value.

[0072] A passivation layer may be disposed on the second electrode 140. Although not shown in the figure, the passivation layer may overlap at least a part of the second electrode 140.

[0073] As described above, since the second electrode 140 includes the protrusion 142 and the extension 144, and the lower frame 150 disposed in the cavity C is provided, the occurrence of parasitic noise and notch can be reduced.

[0074] Therefore, the performance of the bulk acoustic wave resonator 100 can be improved.

[0075] This will be described in more detail below. As Figure 2 shown, it can be seen that compared with the prior art in which a frame and a groove are provided in the second electrode, the bulk acoustic wave resonator 100 according to the above embodiment can reduce the occurrence of parasitic noise and notch.

[0076] According to the resonator of the prior art, in which the frame and the groove are provided in the second electrode, the frame and the groove are formed in the second electrode by a fine etching and deposition process on the second electrode during manufacturing. However, the influence of the chemical process of removing the mask layer after forming the mask layer during the etching and deposition process and the uneven etching effect caused by the shielding during the plasma etching process occur. Therefore, due to the increase of the process error between the processes, the ideal structure shape may not be achieved, and a fine step and / or gradient may be added around the groove, which in turn causes parasitic noise and / or notch.

[0077] However, in the BAW resonator 100 according to the present disclosure, since the second electrode 140 includes the protrusion 142 and the extension 144 and is provided with the lower frame 150 disposed in the cavity C, the related art process is not performed, thereby preventing the occurrence of parasitic noise and notch.

[0078] Hereinafter, a performance change according to a thickness difference of the protrusion and the extension of the second electrode and a width of the first region R will be described.

[0079] Figure 3 is a diagram showing a difference in thickness between a protruding portion and an extending portion of a second electrode and a width of a first region, Figure 4 is a graph showing that when the thickness difference between the protruding portion and the extending portion of the second electrode is A graph showing the value of S11 of the input return loss according to the width of the first region R when (angstroms), Figure 5 is a graph showing that when the thickness difference between the protruding portion and the extending portion of the second electrode is A graph showing the value of S11 according to the width of the first region R; and Figure 6 is a graph showing that when the thickness difference between the protruding portion and the extending portion of the second electrode is Graph showing the value of S11 according to the width of the first region.

[0080] in addition, Figure 4 It is shown that the thickness difference Δt between the protrusion 142 and the extension 144 of the second electrode 140 is fixed to Graph showing the value of S11 when the width W1 of the first region R is 1.2 μm (micrometer), 1.6 μm, 2.0 μm, 2.4 μm, and 2.8 μm. Figure 4 As shown, it can be seen that notching occurs when the width W1 of the first region R is 2.0 μm or more. Here, the thickness difference Δt between the protrusion 142 and the extension 144 of the second electrode 140 refers to a value obtained by subtracting the second thickness t2 (thickness of the extension 144) from the first thickness t1 (thickness of the protrusion 142). In addition, the width W1 of the first region R refers to the distance in the horizontal direction between the end of the protrusion 142 and the inner end of the lower frame 150.

[0081] In addition, if Figure 5 As shown, it can be seen that when the thickness difference Δt between the protrusion 142 and the extension 144 of the second electrode 140 is And the notch occurs when the width W1 of the first region R is 2.4 μm or more. Figure 6 As shown, it can be seen that when the thickness difference Δt between the protrusion 142 and the extension 144 of the second electrode 140 is And notching occurs when the width W1 of the first region R is 2.8 μm or more.

[0082] In addition, in order to make the thickness difference Δt between the protrusion 142 and the extension 144 of the second electrode 140 In order to minimize parasitic noise when the first region R has a width W1 of 1.6 μm or more, the width W1 of the first region R needs to be 1.6 μm or more. In order to minimize parasitic noise when the first region R has a width W1 of 1.6 μm or more, the width W1 of the first region R needs to be 1.6 μm or more. In order to minimize the parasitic noise when the first region R is used, the width W1 of the first region R needs to be 2.0 μm or more.

[0083] In addition, since the difference between the width W1 of the first region R where the minimum parasitic noise occurs and the width W2 of the first region R where the notch occurs is large, the performance variation caused by the process error can be reduced. For example, when the thickness difference Δt between the protrusion 142 and the extension 144 of the second electrode 140 is When the difference between the width W1 of the first region R where the minimum parasitic noise occurs and the width W1 of the first region R where the notch occurs may be 0.4 μm, and when the thickness difference Δt between the protrusion 142 and the extension 144 of the second electrode 140 is When the difference between the width W1 of the first region R where the minimum parasitic noise occurs and the width W1 of the first region R where the notch occurs may be 0.8 μm. In addition, when the thickness difference Δt between the protrusion 142 and the extension 144 of the second electrode 140 is When the first region R where the minimum parasitic noise occurs has a width W1, the difference between the width W1 of the first region R where the notch occurs may be 0.8 μm. Therefore, the thickness difference Δt between the protrusion 142 and the extension 144 of the second electrode 140 is Compared with the case where the thickness difference Δt between the protrusion 142 and the extension 144 of the second electrode 140 is and In this case, the performance variation caused by process errors can be reduced.

[0084] Figure 7 is a schematic configuration diagram showing a partial configuration of a bulk acoustic wave resonator according to an example embodiment in the present disclosure.

[0085] Reference Figure 7 The BAW resonator 200 may include, for example, a substrate 110 , a first electrode 220 , a piezoelectric layer 130 , a second electrode 140 , and a lower frame 250 .

[0086] In addition, the substrate 110 , the piezoelectric layer 130 , and the second electrode 140 are the same components as those described above, and further detailed description of the substrate 110 , the piezoelectric layer 130 , and the second electrode 140 will be omitted.

[0087] The cavity C may be disposed between the first electrode 220 and the substrate 110. As an example, the first electrode 220 may be used as any one of an input electrode inputting an electrical signal such as a radio frequency (RF) signal and an output electrode outputting an electrical signal such as a radio frequency (RF) signal.

[0088] In addition, the first electrode 220 may be formed using, for example, a conductive material such as molybdenum (Mo) or an alloy thereof. However, the first electrode 220 is not limited thereto and may be formed using a conductive material such as ruthenium (Ru), tungsten (W), iridium (Ir), platinum (Pt), copper (Cu), titanium (Ti), tantalum (Ta), nickel (Ni) or chromium (Cr) or an alloy thereof.

[0089] The lower frame 250 may be disposed to be spaced apart from the substrate 110, and a portion of the cavity C may be disposed below the lower frame 250. As an example, the lower frame 250 may be formed to have a ring shape on the bottom surface of the first electrode 220. In addition, the lower frame 250 may be formed using an insulating material having a density lower than that of the first electrode 220. For example, the lower frame 250 may be formed using an insulating material such as silicon dioxide (SiO2), silicon nitride (Si3N4), and aluminum oxide (Al2O3). In addition, the inner end of the lower frame 250 and the end of the protrusion 142 may be disposed to be spaced apart in the horizontal direction.

[0090] In addition, in the present exemplary embodiment, the effective region S, the first region R, and the second region U may also be continuously provided.

[0091] In this way, the lower frame 250 can be formed using an insulating material having a density lower than that of the first electrode 220. Therefore, the acoustic impedance value of the transverse wave generated at the anti-resonance frequency becomes very large, and the difference between z2 and z0 can be increased. Therefore, the BAW resonator 200 can obtain higher Q performance. In addition, when the value of z2 in the second region U increases compared to z0 in the effective region S, k corresponding to the electromechanical coupling coefficient can also be improved. t2 performance.

[0092] That is, as shown in Table 1 below, when the lower frame 250 is formed using molybdenum (Mo) and silicon dioxide (SiO2), it can be seen that the performance of the BAW resonator 200 is different. In more detail, it can be seen that, compared with the case where the lower frame 250 is formed using molybdenum (Mo) which is the same material as the first electrode 220, in the case where silicon dioxide (SiO2) (insulator) is used as the material of the lower frame 250, k t 2 0.1% greater and the Q performance is about 660 greater.

[0093] This behavior occurs because the acoustic impedance value of the transverse wave generated at the anti-resonance frequency becomes large when silicon dioxide (SiO 2 ) (insulator) is used as the material of the lower frame 250 .

[0094] [Table 1]

[0095] Lower frame material <![CDATA[k t 2 [%]]]> Q Q Molybdenum (Mo) 7.9 1190 2390 <![CDATA[Silicon dioxide (SiO2)]]> 8.0 1280 3050

[0096] Figure 8 is a schematic configuration diagram showing a partial configuration of a bulk acoustic wave resonator according to an example embodiment in the present disclosure.

[0097] Reference Figure 8 The BAW resonator 300 may include, for example, a substrate 110 , a first electrode 120 , a piezoelectric layer 130 , a second electrode 340 , and a passivation layer 360 .

[0098] In addition, since the first electrode 120 , the piezoelectric layer 130 , and the lower frame 150 are the same components as those described in the BAW resonator 100 , further detailed description thereof will be omitted herein.

[0099] The second electrode 340 may overlap at least a portion of the piezoelectric layer 130. In addition, the second electrode 340 may be used as any one of an input electrode for inputting an electrical signal such as a radio frequency (RF) signal and an output electrode for outputting an electrical signal such as a radio frequency (RF) signal. That is, in the case where the first electrode 120 is used as an input electrode, the second electrode 340 may be used as an output electrode, and in the case where the first electrode 120 is used as an output electrode, the second electrode 340 may be used as an input electrode.

[0100] The second electrode 340 may be formed using, for example, a conductive material such as molybdenum (Mo) or an alloy thereof. However, the second electrode 340 is not limited thereto and may be formed using a conductive material such as ruthenium (Ru), tungsten (W), iridium (Ir), platinum (Pt), copper (Cu), titanium (Ti), tantalum (Ta), nickel (Ni), or chromium (Cr), or an alloy thereof.

[0101] The passivation layer 360 may overlap at least a portion of the second electrode 340. In addition, the passivation layer 360 may be used to prevent the first electrode 120 and the second electrode 340 from being damaged during the process. As an example, the passivation layer 360 may be formed using an insulating material. In other words, the passivation layer 360 may be formed using an insulating material having a density lower than that of the first electrode 120, such as silicon dioxide (SiO2), silicon nitride (Si3N4), and aluminum oxide (Al2O3). In addition, the passivation layer 360 may include a protrusion 362 having a first thickness T1 and an extension 364 having a thickness less than that of the protrusion 362. The thickness of the extension 364 is defined as a second thickness T2.

[0102] In addition, in the present exemplary embodiment, the effective region S, the first region R, and the second region U may also be continuously provided.

[0103] As described above, since the passivation layer 360 includes the protrusion 362 and the extension 364, the value of the lateral wave number β1 in the first region R can be formed smaller than the case where the second electrode 140 of the above-mentioned BAW resonator 100 includes the protrusion 142 and the extension 144. As a result, since the value of the width W1 of the first region R can be increased, the influence of notches and the like that may occur due to process errors can be reduced.

[0104] Hereinafter, a property variation according to a thickness difference of the protrusion and the extension of the passivation layer and a width of the first region R will be described.

[0105] Fig. 9 is a diagram showing a difference in thickness between a protruding portion and an extending portion of a passivation layer and a width of a first region, Fig.10 It shows that when the thickness difference between the protrusion and the extension of the passivation layer is is a graph showing the value of S11 according to the width of the first region R, Fig.11 It shows that when the thickness difference between the protrusion and the extension of the passivation layer is is a graph of the value of S11 according to the width of the first region R, and Fig.12 It shows that when the thickness difference between the protrusion and the extension of the passivation layer is Graph showing the value of S11 according to the width of the first region.

[0106] In order to make the thickness difference ΔT between the protrusion 362 and the extension 364 of the passivation layer 360 In order to minimize parasitic noise when the first region R is formed, the width W1 of the first region R needs to be 2.8 μm or more. Fig.10 As shown, it can be seen that notching occurs when the width W1 of the first region R is 4.0 μm or more.

[0107] In addition, in order to make the thickness difference ΔT between the protrusion 362 and the extension 364 of the passivation layer 360 In order to minimize parasitic noise when the first region R is formed, the width W1 of the first region R needs to be 2.8 μm or more. Fig.11 As shown, it can be seen that notching occurs when the width W1 of the first region R is 4.4 μm or more.

[0108] In addition, in order to make the thickness difference ΔT between the protrusion 362 and the extension 364 of the passivation layer 360 In order to minimize parasitic noise when the first region R is formed, the width W1 of the first region R needs to be 3.2 μm or more. Fig.12 As shown, it can be seen that when the width W1 of the first region R is 4.8 μm or more, notching occurs.

[0109] Therefore, when the passivation layer 360 includes the protrusion 362 and the extension 364, the difference between the width W1 of the first region R where the minimum parasitic noise occurs and the width W1 of the first region R where the trap occurs can be relatively increased compared to the case where the second electrode 140 of the above-mentioned BAW resonator 100 includes the protrusion 142 and the extension 144.

[0110] Fig.13 is a schematic configuration diagram showing a partial configuration of a bulk acoustic wave resonator according to an example embodiment in the present disclosure.

[0111] Reference Fig.13 The BAW resonator 400 may include a substrate 110 , a first electrode 420 , a piezoelectric layer 130 , a second electrode 440 , a lower frame 450 , and a passivation layer 460 .

[0112] In addition, the substrate 110 and the piezoelectric layer 130 are the same components as the substrate 110 and the piezoelectric layer 130 described above, and further detailed description thereof will be omitted.

[0113] The cavity C may be disposed between the first electrode 420 and the substrate 110. As an example, the first electrode 420 may be used as any one of an input electrode inputting an electrical signal such as a radio frequency (RF) signal and an output electrode outputting an electrical signal such as a radio frequency (RF) signal.

[0114] In addition, the first electrode 420 may be formed using, for example, a conductive material such as molybdenum (Mo) or an alloy thereof. However, the first electrode 420 is not limited thereto and may be formed using a conductive material such as ruthenium (Ru), tungsten (W), iridium (Ir), platinum (Pt), copper (Cu), titanium (Ti), tantalum (Ta), nickel (Ni) or chromium (Cr) or an alloy thereof.

[0115] The second electrode 440 may overlap at least a portion of the piezoelectric layer 130. In addition, the second electrode 440 may be used as any one of an input electrode for inputting an electrical signal such as a radio frequency (RF) signal and an output electrode for outputting an electrical signal such as a radio frequency (RF) signal. That is, in the case where the first electrode 420 is used as an input electrode, the second electrode 440 may be used as an output electrode, and in the case where the first electrode 420 is used as an output electrode, the second electrode 440 may be used as an input electrode.

[0116] The second electrode 440 may be formed using, for example, a conductive material such as molybdenum (Mo) or an alloy thereof. However, the second electrode 440 is not limited thereto and may be formed using a conductive material such as ruthenium (Ru), tungsten (W), iridium (Ir), platinum (Pt), copper (Cu), titanium (Ti), tantalum (Ta), nickel (Ni), or chromium (Cr), or an alloy thereof.

[0117] The lower frame 450 may be disposed to be spaced apart from the substrate 110, and a portion of the cavity C may be disposed below the lower frame 450. In addition, the lower frame 450 may be formed on the bottom surface of the first electrode 420, and may have a ring shape. In addition, the lower frame 450 may be formed using an insulating material having a lower density than that of the first electrode 420. For example, the lower frame 450 may be formed using an insulating material such as silicon dioxide (SiO2), silicon nitride (Si3N4), and aluminum oxide (Al2O3). In addition, the inner end of the lower frame 450 and the end of the protrusion 462 to be described later may be disposed to be spaced apart in the horizontal direction.

[0118] The passivation layer 460 may overlap at least a portion of the second electrode 440. In addition, the passivation layer 460 may be used to prevent the first electrode 420 and the second electrode 440 from being damaged during the process. As an example, the passivation layer 460 may be formed using an insulating material. In other words, the passivation layer 460 may be formed using an insulating material having a density lower than that of the first electrode 420, such as silicon dioxide (SiO2), silicon nitride (Si3N4), and aluminum oxide (Al2O3). In addition, the passivation layer 460 may include a protrusion 462 having a first thickness T1 and an extension 464 having a thickness smaller than that of the protrusion 462. The thickness of the extension 464 is defined as a second thickness T2.

[0119] In addition, in the present exemplary embodiment, the effective region S, the first region R, and the second region U may also be continuously provided.

[0120] As described above, the lower frame 450 may be formed using an insulating material having a lower density than the first electrode 420. Therefore, the acoustic impedance value of the transverse wave generated at the anti-resonance frequency becomes very large, and the difference between z2 and z0 may increase. Therefore, the BAW resonator 400 may obtain a higher Q performance. In addition, when the value of z2 in the second region U increases compared to z0 in the effective region S, k corresponding to the electromechanical coupling coefficient may also be increased. t 2 performance.

[0121] In addition, since the passivation layer 460 includes the protrusion 462 and the extension 464, the value of the lateral wave number β1 in the first region R can be formed to be smaller than the case where the second electrode 140 of the above-mentioned BAW resonator 100 includes the protrusion 142 and the extension 144. As a result, since the value of the width W1 of the first region R can be increased, the influence of notches and the like that may occur due to process errors can be reduced.

[0122] Fig.14 is a schematic configuration diagram showing a partial configuration of a bulk acoustic wave resonator according to an example embodiment in the present disclosure.

[0123] Reference Fig.14 , the BAW resonator 500 may include a substrate 110 , an additional layer 520 , a first electrode 530 , a piezoelectric layer 130 , a second electrode 540 , a lower frame 550 , and a passivation layer 560 .

[0124] In addition, since the substrate 110 and the piezoelectric layer 130 are the same components as those in the above-described BAW resonator 100 , further detailed description thereof will be omitted.

[0125] The additional layer 520 may form the cavity C together with the substrate 110. In addition, the additional layer 520 serves to improve the crystallinity of the first electrode 530 and the piezoelectric layer 130. In addition, the additional layer 520 may serve as a mechanical support layer to relieve stress, and may be used to prevent the first electrode 530 from being damaged when a sacrificial layer (not shown) is removed when the cavity C is formed during the manufacturing process.

[0126] For example, the additional layer 520 may be formed using an insulating material such as aluminum nitride (AlN), silicon dioxide (SiO 2 ), silicon nitride (Si 3 N 4 ), and aluminum oxide (Al 2 O 3 ).

[0127] The first electrode 530 may overlap at least a portion of the additional layer 520. The first electrode 530 may function as any one of an input electrode inputting an electrical signal such as a radio frequency (RF) signal and an output electrode outputting an electrical signal such as a radio frequency (RF) signal.

[0128] In addition, the first electrode 530 may be formed using, for example, a conductive material such as molybdenum (Mo) or an alloy thereof. However, the first electrode 530 is not limited thereto and may be formed using a conductive material such as ruthenium (Ru), tungsten (W), iridium (Ir), platinum (Pt), copper (Cu), titanium (Ti), tantalum (Ta), nickel (Ni) or chromium (Cr) or an alloy thereof.

[0129] The second electrode 540 may overlap at least a portion of the piezoelectric layer 130. In addition, the second electrode 540 may be used as any one of an input electrode for inputting an electrical signal such as a radio frequency (RF) signal and an output electrode for outputting an electrical signal such as a radio frequency (RF) signal. That is, in the case where the first electrode 530 is used as an input electrode, the second electrode 540 may be used as an output electrode, and in the case where the first electrode 530 is used as an output electrode, the second electrode 540 may be used as an input electrode.

[0130] The second electrode 540 may be formed using, for example, a conductive material such as molybdenum (Mo) or an alloy thereof. However, the second electrode 540 is not limited thereto and may be formed using a conductive material such as ruthenium (Ru), tungsten (W), iridium (Ir), platinum (Pt), copper (Cu), titanium (Ti), tantalum (Ta), nickel (Ni), or chromium (Cr), or an alloy thereof.

[0131] In addition, the second electrode 540 may include a protrusion 542 having a first thickness t1 and an extension 544 having a thickness smaller than that of the protrusion 542. The thickness of the extension 544 is defined as a second thickness t2.

[0132] In addition, the area in which the protrusion 542, the piezoelectric layer 130 and the first electrode 530 are set to be completely overlapped is defined as an effective area S, the area between the end of the protrusion 542 and the inner end of the lower frame 550 is defined as a first area R, and the area in which the extension 544 and the lower frame 550 are set to be overlapped is defined as a second area U.

[0133] In addition, the first region R may be disposed outside the effective region S, and the second region U may be disposed outside the first region R. In addition, the effective region S, the first region R, and the second region U may be continuously disposed.

[0134] In addition, the frequencies in the effective area S, the first area R and the second area U are respectively referred to as f0, f1 and f2, the transverse wave numbers in the effective area S, the first area R and the second area U are respectively referred to as β0, β1 and β2, and the acoustic impedances in the effective area S, the first area R and the second area U are respectively referred to as z0, z1 and z2.

[0135] In addition, the frequencies f0, f1, and f2 in the active region S, the first region R, and the second region U may have the relationship of f2 < f0 < f1.

[0136] In addition, at the resonant frequency, β0 may be 0, β1 may be a real value, and β2 may be an imaginary value.

[0137] The lower frame 550 may be set to be spaced apart from the substrate 110, and a part of the cavity C may be disposed below the lower frame 550. In addition, the lower frame 550 may be formed on the bottom surface of the additional layer 520 and may have an annular shape. In addition, the lower frame 550 may be formed of an insulating material having a density lower than that of the first electrode 530. For example, the lower frame 550 may be formed of an insulating material such as silicon dioxide (SiO2), silicon nitride (Si3N4), and aluminum oxide (Al2O3). In addition, the inner end of the lower frame 550 and the end of the protrusion 542 may be set to be spaced apart in the horizontal direction.

[0138] The passivation layer 560 may be stacked on at least a part of the second electrode 540. In addition, the passivation layer 560 may be used to prevent damage to the first electrode 530 and the second electrode 540 during the process. As an example, the passivation layer 560 may be formed of an insulating material. In other words, the passivation layer 560 may be formed of an insulating material such as silicon dioxide (SiO2), silicon nitride (Si3N4), and aluminum oxide (Al2O3).

[0139] Fig.15 is a schematic configuration diagram showing a partial configuration of a bulk acoustic wave resonator according to an exemplary embodiment in the present disclosure.

[0140] Referring to Fig.15 , the bulk acoustic wave resonator 600 may include a substrate 110, an additional layer 520, a first electrode 530, a piezoelectric layer 130, a second electrode 640, a lower frame 550, and a passivation layer 660.

[0141] In addition, since the substrate 110 and the piezoelectric layer 130 are the same as the components in the bulk acoustic wave resonator 100, and the additional layer 520, the first electrode 530, and the lower frame 550 are the same as the components in the above-mentioned bulk acoustic wave resonator 500, further detailed description thereof will be omitted here.

[0142] The second electrode 640 may be stacked on at least a part of the piezoelectric layer 130. In addition, the second electrode 640 may be used as either an input electrode for inputting an electrical signal such as a radio frequency (RF) signal or an output electrode for outputting an electrical signal such as a radio frequency (RF) signal. That is, when the first electrode 530 is used as an input electrode, the second electrode 640 may be used as an output electrode, and when the first electrode 530 is used as an output electrode, the second electrode 640 may be used as an input electrode.

[0143] The second electrode 640 may be formed using, for example, a conductive material such as molybdenum (Mo) or an alloy thereof. However, the second electrode 640 is not limited thereto and may be formed using a conductive material such as ruthenium (Ru), tungsten (W), iridium (Ir), platinum (Pt), copper (Cu), titanium (Ti), tantalum (Ta), nickel (Ni), or chromium (Cr), or an alloy thereof.

[0144] The passivation layer 660 may overlap at least a portion of the second electrode 640. In addition, the passivation layer 660 may be used to prevent the first electrode 530 and the second electrode 640 from being damaged during the process. As an example, the passivation layer 660 may be formed using an insulating material. In other words, the passivation layer 660 may be formed using an insulating material having a density lower than that of the first electrode 530, such as silicon dioxide (SiO2), silicon nitride (Si3N4), and aluminum oxide (Al2O3). In addition, the passivation layer 660 may include a protrusion 662 having a first thickness T1 and an extension 664 having a thickness smaller than that of the protrusion 662. The thickness of the extension 664 is defined as a second thickness T2.

[0145] In addition, in the present exemplary embodiment, the effective region S, the first region R, and the second region U may also be continuously provided.

[0146] Fig.16 is a schematic configuration diagram showing a partial configuration of a bulk acoustic wave resonator according to an example embodiment in the present disclosure.

[0147] Reference Fig.16 , the BAW resonator 700 may include a substrate 110 , an additional layer 520 , a first electrode 530 , a piezoelectric layer 130 , a second electrode 740 , a lower frame 550 , and a passivation layer 560 .

[0148] In addition, since the substrate 110 and the piezoelectric layer 130 are the same as those in the BAW resonator 100, and the additional layer 520, the first electrode 530, the lower frame 550 and the passivation layer 560 are the same as those in the BAW resonator 500, further detailed description thereof will be omitted herein.

[0149] The second electrode 740 may overlap at least a portion of the piezoelectric layer 130. In addition, the second electrode 740 may be used as any one of an input electrode for inputting an electrical signal such as a radio frequency (RF) signal and an output electrode for outputting an electrical signal such as a radio frequency (RF) signal. That is, in the case where the first electrode 530 is used as an input electrode, the second electrode 740 may be used as an output electrode, and in the case where the first electrode 530 is used as an output electrode, the second electrode 740 may be used as an input electrode.

[0150] The second electrode 740 may be formed using, for example, a conductive material such as molybdenum (Mo) or an alloy thereof. However, the second electrode 740 is not limited thereto and may be formed using a conductive material such as ruthenium (Ru), tungsten (W), iridium (Ir), platinum (Pt), copper (Cu), titanium (Ti), tantalum (Ta), nickel (Ni), or chromium (Cr), or an alloy thereof.

[0151] In addition, the second electrode 740 may include a protrusion 742 having a first thickness t1, an extension 744 having a thickness smaller than that of the protrusion 742, and a frame portion 746 disposed outside the extension 744. The thickness of the extension 744 is defined as a second thickness t2, and the thickness of the frame portion 746 is defined as a third thickness t3. In addition, the first thickness t1, the second thickness t2, and the third thickness t3 have a relationship of t3>t1>t2.

[0152] In addition, the area where the protrusion 742, the piezoelectric layer 130 and the first electrode 530 are set to be completely overlapped is defined as an effective area S, the area between the end of the protrusion 742 and the inner end of the lower frame 550 is defined as a first area R, the area between the inner end of the lower frame 550 and the inner end of the frame portion 746 is defined as a second area U, and the area where the lower frame 550 and the frame portion 746 are set to overlap is defined as a third area P.

[0153] In addition, the first region R may be disposed outside the effective region S, the second region U may be disposed outside the first region R, and the third region P may be disposed outside the second region U. In addition, the effective region S, the first region R, the second region U, and the third region P may be disposed continuously.

[0154] In addition, the frequencies in the effective area S, the first area R, the second area U and the third area P are respectively referred to as f0, f1, f2 and f3, the transverse wave numbers in the effective area S, the first area R, the second area U and the third area P are respectively referred to as β0, β1, β2 and β3, and the acoustic impedances in the effective area S, the first area R, the second area U and the third area P are respectively referred to as z0, z1, z2 and z3.

[0155] As described above, since the second electrode 740 includes the frame portion 746, the lower frame 550 and the frame portion 746 can function as a double reflection boundary structure. Therefore, the reflection efficiency of a plurality of transverse waves existing near the anti-resonance frequency can be improved. As a result, the Q performance of the bulk acoustic wave resonator 700 can be improved.

[0156] In addition, in the present exemplary embodiment, the acoustic impedance values ​​z2 and z3 may have larger values ​​than z0. Therefore, the Q performance of the BAW resonator 700 may be further improved.

[0157] Fig.17is a schematic configuration diagram showing a partial configuration of a bulk acoustic wave resonator according to an example embodiment in the present disclosure.

[0158] Reference Fig.17 , the BAW resonator 800 may include a substrate 110 , an additional layer 520 , a first electrode 530 , a piezoelectric layer 130 , a second electrode 840 , a lower frame 550 , and a passivation layer 860 .

[0159] In addition, since the substrate 110 and the piezoelectric layer 130 are the same components as those of the BAW resonator 100, and the additional layer 520, the first electrode 530 and the lower frame 550 are the same components as those of the BAW resonator 500, further detailed description thereof will be omitted here.

[0160] The second electrode 840 may overlap at least a portion of the piezoelectric layer 130. In addition, the second electrode 840 may be used as any one of an input electrode for inputting an electrical signal such as a radio frequency (RF) signal and an output electrode for outputting an electrical signal such as a radio frequency (RF) signal. That is, in the case where the first electrode 530 is used as an input electrode, the second electrode 840 may be used as an output electrode, and in the case where the first electrode 530 is used as an output electrode, the second electrode 840 may be used as an input electrode.

[0161] The second electrode 840 may be formed using, for example, a conductive material such as molybdenum (Mo) or an alloy thereof. However, the second electrode 840 is not limited thereto and may be formed using a conductive material such as ruthenium (Ru), tungsten (W), iridium (Ir), platinum (Pt), copper (Cu), titanium (Ti), tantalum (Ta), nickel (Ni), or chromium (Cr), or an alloy thereof.

[0162] The second electrode 840 may include a frame portion 842 having a thickness thicker than other portions.

[0163] The passivation layer 860 may overlap at least a portion of the second electrode 840. In addition, the passivation layer 860 may be used to prevent the first electrode 530 and the second electrode 840 from being damaged during the process. As an example, the passivation layer 860 may be formed using an insulating material. In other words, the passivation layer 860 may be formed using an insulating material having a density lower than that of the first electrode 530, such as silicon dioxide (SiO2), silicon nitride (Si3N4), and aluminum oxide (Al2O3). In addition, the passivation layer 860 may include a protrusion 862 having a first thickness T1, an extension 864 having a thickness smaller than that of the protrusion 862, and an edge portion 866 of the frame portion 842 provided to cover the second electrode 840. The thickness of the extension 864 is defined as the second thickness T2, and the thickness of the edge portion 866 is defined as the third thickness T3. In addition, the first thickness T1 may have a value greater than the second thickness T2.

[0164] In addition, the area where the protrusion 862, the piezoelectric layer 130 and the first electrode 530 are arranged to be entirely overlapped is defined as an effective area S, the area between the end of the protrusion 862 and the inner end of the lower frame 550 is defined as a first area R, the area between the inner end of the lower frame 550 and the inner end of the frame portion 842 is defined as a second area U, and the area where the lower frame 550 and the frame portion 842 are arranged to overlap is defined as a third area P.

[0165] In addition, the first region R may be disposed outside the effective region S, the second region U may be disposed outside the first region R, and the third region P may be disposed outside the second region U. In addition, the effective region S, the first region R, the second region U, and the third region P may be disposed continuously.

[0166] In addition, the frequencies in the effective area S, the first area R, the second area U and the third area P are respectively referred to as f0, f1, f2 and f3, the transverse wave numbers in the effective area S, the first area R, the second area U and the third area P are respectively referred to as β0, β1, β2 and β3, and the acoustic impedances in the effective area S, the first area R, the second area U and the third area P are respectively referred to as z0, z1, z2 and z3.

[0167] As described above, since the second electrode 840 includes the frame portion 842, the lower frame 550 and the frame portion 842 can be used as a double reflection boundary structure. Therefore, the reflection efficiency of a plurality of transverse waves existing near the anti-resonance frequency can be improved. As a result, the Q performance of the bulk acoustic wave resonator 800 can be improved.

[0168] In addition, in the present exemplary embodiment, the acoustic impedance values ​​z2 and z3 may have larger values ​​compared to z0. Therefore, the Q performance of the BAW resonator 800 may be further improved.

[0169] Fig.18 is a schematic cross-sectional view showing a bulk acoustic wave resonator according to an example embodiment in the present disclosure, and Fig.19 It is shown Fig.18 An enlarged view of part A of FIG.

[0170] Reference Fig.18 and Fig.19 The BAW resonator 1000 according to the example embodiment in the present disclosure may include a substrate 1010, a sacrificial layer 1020, an anti-etching portion 1030, a membrane layer 1040, a first electrode 1050, a piezoelectric layer 1060, a second electrode 1070, an insertion layer 1080, a passivation layer 1090, a metal pad 1100, and a lower frame 1110.

[0171] The substrate 1010 may be a silicon substrate. For example, a silicon wafer or a silicon-on-insulator (SOI) type substrate may be used as the substrate 1010 .

[0172] The insulating layer 1012 may be formed on the upper surface of the substrate 1010 and may electrically isolate components disposed on the substrate 1010 from the substrate 1010. In addition, the insulating layer 1012 may prevent the substrate 1010 from being etched by an etching gas when forming the cavity C in a process of manufacturing a BAW resonator.

[0173] In this case, the insulating layer 1012 can be formed using at least one of silicon dioxide (SiO2), silicon nitride (Si3N4), aluminum oxide (Al2O3) and aluminum nitride (AlN), and can be formed by any one of a chemical vapor deposition process, a radio frequency (RF) magnetron sputtering process and an evaporation process.

[0174] The sacrificial layer 1020 may be formed on the insulating layer 1012, and the cavity C and the etching prevention part 1030 may be provided in the sacrificial layer 1020. The cavity C may be formed by removing a portion of the sacrificial layer 1020 when manufacturing the BAW resonator. As described above, when the cavity C is formed in the sacrificial layer 1020, the first electrode 1050 and the like formed on the sacrificial layer 1020 may be flat.

[0175] The anti-etching part 1030 may be disposed along the boundary of the cavity C. The anti-etching part 1030 may be used to prevent etching from being performed beyond the cavity region in a process of forming the cavity C.

[0176] The film layer 1040 may form the cavity C together with the substrate 1010. In addition, the film layer 1040 may be formed using a material having low reactivity with an etching gas when removing the sacrificial layer 1020. In addition, as the film layer 1040, a dielectric layer including a material selected from the group consisting of, for example, silicon nitride (Si3N4), silicon dioxide (SiO2), manganese oxide (MnO), zirconium oxide (ZrO2), aluminum nitride (AlN), lead zirconate titanate (PZT), gallium arsenide (GaAs), hafnium oxide (HfO2), aluminum oxide (Al2O3), titanium oxide (TiO2), and zinc oxide (ZnO) may be used.

[0177] In addition, a seed layer (not shown) formed using aluminum nitride (AlN) may be formed on the film layer 1040. That is, the seed layer may be disposed between the film layer 1040 and the first electrode 1050. In addition to AlN, a dielectric or a metal having a hexagonal close-packed (HCP) structure may be used to form the seed layer. As an example, when the seed layer is formed using a metal, the seed layer may be formed using titanium (Ti). However, the seed layer is not limited thereto and may also be formed instead of the film layer 1040.

[0178] The first electrode 1050 may be formed on the membrane layer 1040, and a portion of the first electrode 1050 may be disposed above the cavity C. In addition, the first electrode 1050 may be used as any one of an input electrode for inputting an electrical signal such as a radio frequency (RF) signal and an output electrode for outputting an electrical signal such as a radio frequency (RF) signal.

[0179] The first electrode 1050 may be formed using, for example, a conductive material such as molybdenum (Mo) or an alloy thereof. However, the first electrode 1050 is not limited thereto and may be formed using a conductive material such as ruthenium (Ru), tungsten (W), iridium (Ir), platinum (Pt), copper (Cu), titanium (Ti), tantalum (Ta), nickel (Ni), or chromium (Cr), or an alloy thereof.

[0180] The piezoelectric layer 1060 may be provided to cover at least the first electrode 1050 provided above the cavity C. In addition, the piezoelectric layer 1060 may be a portion causing a piezoelectric effect that converts electrical energy into mechanical energy in the form of elastic waves, and may be formed using one of aluminum nitride (AlN), zinc oxide (ZnO), and lead zirconate titanate (PZT, PbZrTiO3). In particular, in the case where the piezoelectric layer 1060 is formed using aluminum nitride (AlN), the piezoelectric layer 1060 may further include a rare earth metal. As an example, the rare earth metal may include at least one of scandium (Sc), erbium (Er), yttrium (Y), and lanthanum (La). In addition, as an example, the piezoelectric layer 1060 may further include at least one of titanium (Ti), zirconium (Zr), hafnium (Hf), tantalum (Ta), and niobium (Nb) as transition metals. In addition, the piezoelectric layer 1060 may further include magnesium (Mg) (divalent metal).

[0181] In addition, the piezoelectric layer 1060 may include a piezoelectric portion 1062 formed flatly and a bent portion 1064 extending from the piezoelectric portion 1062 .

[0182] The piezoelectric portion 1062 may be a portion directly stacked on an upper surface of the first electrode 1050. Thus, the piezoelectric portion 1062 may be interposed between the first electrode 1050 and the second electrode 1070, and may be formed in a flat shape together with the first electrode 1050 and the second electrode 1070.

[0183] The bent portion 1064 may be disposed on the insertion layer 1080 to be described below, and may protrude along the shape of the insertion layer 1080. Therefore, the piezoelectric layer 1060 may be bent at a boundary between the piezoelectric portion 1062 and the bent portion 1064, and the bent portion 1064 may protrude according to the thickness and shape of the insertion layer 1080.

[0184] The bent portion 1064 may be divided into an inclined portion 1064 a and an edge portion 1064 b .

[0185] The inclined portion 1064a may refer to a portion inclined along an inclined surface L of an insertion layer 1080 to be described below. In addition, the edge portion 1064b may refer to a portion extending outward from the inclined portion 1064a.

[0186] The inclined portion 1064 a may be formed to be parallel to the inclined surface L of the insertion layer 1080 , and an inclined angle of the inclined portion 1064 a may be the same as an inclined angle θ of the inclined surface L of the insertion layer 1080 .

[0187] The second electrode 1070 may be provided to cover at least the piezoelectric layer 1060 provided on the cavity C. The second electrode 1070 may be used as any one of an input electrode for inputting an electrical signal such as a radio frequency (RF) signal and an output electrode for outputting an electrical signal such as a radio frequency (RF) signal. That is, in the case where the first electrode 1050 is used as an input electrode, the second electrode 1070 may be used as an output electrode, and in the case where the first electrode 1050 is used as an output electrode, the second electrode 1070 may be used as an input electrode.

[0188] The second electrode 1070 may be formed using, for example, a conductive material such as molybdenum (Mo) or an alloy thereof. However, the second electrode 1070 is not limited thereto and may be formed using a conductive material such as ruthenium (Ru), tungsten (W), iridium (Ir), platinum (Pt), copper (Cu), titanium (Ti), tantalum (Ta), nickel (Ni), or chromium (Cr), or an alloy thereof.

[0189] The insertion layer 1080 may be disposed between the first electrode 1050 and the piezoelectric layer 1060. The insertion layer 1080 may be formed using a dielectric material such as silicon dioxide (SiO2), aluminum nitride (AlN), aluminum oxide (Al2O3), silicon nitride (Si3N4), manganese oxide (MnO), zirconium oxide (ZrO2), lead zirconate titanate (PZT), gallium arsenide (GaAs), hafnium oxide (HfO2), titanium oxide (TiO2), zinc oxide (ZnO), etc., but may be formed using a material different from that of the piezoelectric layer 1060.

[0190] In addition, at least a portion of the insertion layer 1080 may be disposed between the piezoelectric layer 1060 and the first electrode 1050. As an example, the insertion layer 1080 may have a ring shape.

[0191] A passivation layer 1090 may be formed on the second electrode 1070. In addition, the passivation layer 1090 may serve to prevent the second electrode 1070 and the first electrode 1050 from being damaged during the process.

[0192] In addition, as the passivation layer 1090, a dielectric layer including a material selected from the group consisting of, for example, silicon nitride (Si3N4), silicon dioxide (SiO2), manganese oxide (MnO), zirconium oxide (ZrO2), aluminum nitride (AlN), lead zirconate titanate (PZT), gallium arsenide (GaAs), hafnium oxide (HfO2), aluminum oxide (Al2O3), titanium oxide (TiO2) and zinc oxide (ZnO) can be used.

[0193] In addition, if Fig.19 As shown in more detail in FIG. 1 , the passivation layer 1090 may include a protrusion 1092 having a first thickness T1 and an extension 1094 having a thickness smaller than that of the protrusion 1092. The thickness of the extension 1094 is defined as a second thickness T2.

[0194] In addition, the area where the protrusion 1092, the piezoelectric layer 1060 and the first electrode 1050 are set to be completely overlapped is defined as an effective area S, the area between the end of the protrusion 1092 and the inner end of the lower frame 1110 is defined as a first area R, and the area where the extension 1094 and the lower frame 1110 are set to be overlapped is defined as a second area U.

[0195] In addition, the first region R may be disposed outside the effective region S, and the second region U may be disposed outside the first region R. In addition, the effective region S, the first region R, and the second region U may be continuously disposed.

[0196] The metal pad 1100 may be formed on portions of the first electrode 1050 and the second electrode 1070 where the passivation layer 1090 is not formed. As an example, the metal pad 1100 may be formed using a material such as gold (Au), a gold-tin (Au-Sn) alloy, copper (Cu), a copper-tin (Cu-Sn) alloy, aluminum (Al), an aluminum alloy, etc. For example, the aluminum alloy may be an aluminum-germanium (Al-Ge) alloy.

[0197] The lower frame 1110 may be disposed to be spaced apart from the substrate 1010, and a portion of the cavity C may be disposed below the lower frame 1110. As an example, the lower frame 1110 may be formed to have a ring shape on the bottom surface of the first electrode 1050. In addition, the inner end of the lower frame 1110 and the end of the protrusion 1092 may be disposed to be spaced apart in the horizontal direction, and at least a portion of the lower frame 1110 may overlap with the extension 1094 of the passivation layer 1090. In addition, the lower frame 1110 may be formed using an insulating material having a lower density than that of the first electrode 1050. As an example, the lower frame 1110 may be formed using an insulating material such as silicon dioxide (SiO2), silicon nitride (Si3N4), and aluminum oxide (Al2O3).

[0198] As described above, since the passivation layer 1090 includes the protrusion 1092 and the extension 1094 and is provided with the lower frame 1110 disposed in the cavity C, the occurrence of parasitic noise and notch waves may be reduced.

[0199] Therefore, the performance of the BAW resonator 1000 may be improved.

[0200] As described above, according to the exemplary embodiments in the present disclosure, the occurrence of spurious noise and notches may be reduced.

[0201] Although specific example embodiments have been shown and described above, it will be apparent after understanding the present disclosure that various changes in form and detail may be made in these examples without departing from the spirit and scope of the claims and their equivalents. The examples described herein will be considered as descriptive only, and not for limiting purposes. The description of the features or aspects in each example will be considered as applicable to similar features or aspects in other examples. If the described techniques are performed in a different order, and / or if the components in the described system, architecture, device, or circuit are combined in a different manner and / or replaced or supplemented by other components or their equivalent components in the described system, architecture, device, or circuit, suitable results may be obtained. Therefore, the scope of the present disclosure is not limited by specific embodiments, but by the claims and their equivalents, and all variations within the scope of the claims and their equivalents will be interpreted as included in the present disclosure.

Claims

1. A bulk acoustic wave resonator, comprising: substrate; a first electrode, wherein a cavity is formed between the substrate and the first electrode; a piezoelectric layer disposed on the first electrode and overlapping at least a portion of the first electrode; a second electrode disposed on the piezoelectric layer and overlapping at least a portion of the piezoelectric layer; a passivation layer having at least a portion disposed on the second electrode and overlapping at least a portion of the second electrode; and a lower frame spaced apart from the substrate, and a portion of the cavity is disposed between the lower frame and the substrate, wherein either the second electrode or the passivation layer includes a protrusion having a first thickness and an extension having a second thickness smaller than the first thickness, and The inner end of the lower frame and the end of the protrusion are spaced apart in a horizontal direction.

2. The BAW resonator according to claim 1, wherein: At least a portion of the extension portion overlaps the lower frame.

3. The BAW resonator according to claim 1, wherein: The lower frame is formed using the same material as that of the first electrode.

4. The BAW resonator according to claim 1, wherein: The lower frame is disposed under the first electrode and is formed using a material different from that of the first electrode.

5. The BAW resonator according to claim 4, wherein: The lower frame is formed using an insulating material having a density lower than that of the first electrode.

6. The BAW resonator according to claim 1, wherein: The passivation layer includes the protrusion and the extension, and is formed using an insulating material having a density lower than that of the first electrode. 7 . The BAW resonator of claim 1 , further comprising an additional layer disposed between the lower frame and the first electrode.

8. The BAW resonator according to claim 1, wherein: The second electrode includes a frame portion having at least a portion overlapping the lower frame, and a thickness of the frame portion is greater than a thickness of other portions of the second electrode.

9. The BAW resonator according to claim 8, wherein: An inner end of the frame portion and an inner end of the lower frame are spaced apart in the horizontal direction. 10 . The BAW resonator of claim 9 , further comprising an additional layer disposed between the lower frame and the first electrode.

11. The BAW resonator according to claim 9, wherein: The lower frame is disposed under the first electrode and is formed using a material different from that of the first electrode.

12. The BAW resonator according to claim 11, wherein: The lower frame is formed using an insulating material having a density lower than that of the first electrode.

13. The BAW resonator according to claim 9, wherein: The passivation layer includes the protrusion and the extension, and is formed using an insulating material having a density lower than that of the first electrode.

14. The BAW resonator of claim 1, further comprising an anti-etching layer disposed around the cavity. 15 . The BAW resonator of claim 14 , further comprising a sacrificial layer disposed outside the anti-etching layer. 16 . The BAW resonator of claim 14 , further comprising an insertion layer disposed between the first electrode and the piezoelectric layer.

17. A bulk acoustic wave resonator, comprising: substrate; a first electrode, wherein the cavity is disposed between the substrate and the first electrode; a piezoelectric layer disposed on the first electrode and overlapping at least a portion of the first electrode; a second electrode disposed on the piezoelectric layer and overlapping at least a portion of the piezoelectric layer; A passivation layer having at least a portion disposed on the second electrode and overlapping at least a portion of the second electrode; and A lower frame spaced apart from the substrate, with a portion of the cavity disposed between the lower frame and the substrate, wherein either the second electrode or the passivation layer includes a protrusion having a first thickness and an extension having a second thickness smaller than the first thickness, and wherein an active region, a first region, and a second region are continuously disposed, in the active region the protrusion, the piezoelectric layer, and the first electrode are all overlapped, the first region is disposed between the end of the protrusion and the inner end of the lower frame, and the second region is disposed outside the first region and in the second region the extension and the lower frame are overlapped.

18. The BAW resonator of claim 17, wherein: The frequencies f0, f1, and f2 in the active region, the first region, and the second region have the relationship f2 < f0 < f1.

19. The BAW resonator of claim 18, wherein: When the lateral wave numbers in the active region, the first region, and the second region are β0, β1, and β2 respectively, at the resonant frequency, β0 is 0, β1 is a real value, and β2 is an imaginary value.

20. The BAW resonator of claim 18, wherein: When the acoustic impedances in the active region and the second region are z0 and z2 respectively, the value of z2 is greater than the value of z0.

21. A bulk acoustic wave resonator, comprising: A substrate; A first electrode disposed on the substrate and spaced apart from the substrate by a cavity; A piezoelectric layer disposed on the first electrode; A second electrode disposed on the piezoelectric layer; And A lower frame spaced apart from the substrate, with a portion of the cavity disposed between the lower frame and the substrate, wherein the second electrode includes a protrusion and an extension, the protrusion has a first thickness, the extension has a second thickness smaller than the first thickness, and wherein the inner end of the lower frame and the end of the protrusion are spaced apart in the horizontal direction.

22. A bulk acoustic wave resonator, comprising: A substrate; A first electrode disposed on the substrate and spaced apart from the substrate by a cavity; A piezoelectric layer disposed on the first electrode; A second electrode disposed on the piezoelectric layer; An upper layer disposed on the second electrode; And A lower frame spaced apart from the substrate, with a portion of the cavity disposed between the lower frame and the substrate, wherein the upper layer includes a protrusion and an extension, the protrusion has a first thickness, the extension has a second thickness smaller than the first thickness, and wherein the inner end of the lower frame and the end of the protrusion are spaced apart in the horizontal direction.

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