Bulk acoustic wave resonator with laminated protrusion structure, method of manufacturing the same, filter, and electronic device

Abstract

The present application relates to a bulk acoustic wave resonator and a manufacturing method thereof. The resonator includes a substrate, an acoustic mirror, a bottom electrode, a top electrode, and a piezoelectric layer, wherein: a coincident region of the top electrode, the piezoelectric layer, the bottom electrode, and the acoustic mirror in a thickness direction of the resonator constitutes an effective region of the resonator; the top electrode and / or the bottom electrode is provided with a protruding structure along the effective region, the protruding structure includes a first protruding layer and a second protruding layer, the first protruding layer is arranged adjacent to the piezoelectric layer, an outer end of the second protruding layer is away from the piezoelectric layer in the thickness direction of the resonator and is superposed with the first protruding layer, a portion where the first protruding layer and the second protruding layer are superposed with each other constitutes a superposed portion; the protruding structure is provided with a single-layer portion inside the superposed portion, the single-layer portion is arranged between the corresponding electrode and the piezoelectric layer; and a ratio of a thickness of the single-layer portion to a thickness of the superposed portion is not greater than 0.62. The present application also relates to a filter and an electronic device.

Description

TECHNICAL FIELD

[0001] Embodiments of the present application relate to the field of semiconductor, and in particular to a bulk acoustic wave resonator and a manufacturing method thereof, a filter having the resonator, and an electronic device. BACKGROUND

[0002] Electronic devices, as the basic elements of electronic equipment, are widely used in all aspects of our life. Not only are there various electronic devices in the places where we currently use mobile phones, cars, home appliances, etc., but also future technologies such as artificial intelligence, the Internet of Things, and 5G communication, which will change the world, still need to rely on electronic devices as the foundation.

[0003] Electronic devices can exhibit different characteristics and advantages according to different working principles. Among all electronic devices, devices that work using the piezoelectric effect (or inverse piezoelectric effect) are very important. Thin film bulk acoustic resonators have excellent characteristics such as small size (μm level), high resonance frequency (GHz), high quality factor (1000), large power capacity, and good roll-off effect, and their filters are gradually replacing traditional surface acoustic wave (SAW) filters and ceramic filters, playing a huge role in the field of wireless communication radio frequency, and their high sensitivity advantage can also be applied to biological, physical, medical, and other sensing fields. FBAR mainly uses the piezoelectric effect and inverse piezoelectric effect of piezoelectric materials to generate bulk acoustic waves, thereby forming resonance within the device. Because FBAR has a series of inherent advantages such as high quality factor, large power capacity, high frequency (up to 2-10 GHz or even higher), and good compatibility with standard integrated circuits (IC), it can be widely used in high-frequency radio frequency application systems.

[0004] The main structure of FBAR is a "sandwich" structure composed of an electrode-piezoelectric film-electrode, i.e., a piezoelectric material layer is sandwiched between two metal electrode layers. By inputting a sinusoidal signal between the two electrodes, FBAR converts the input electrical signal into mechanical resonance using the inverse piezoelectric effect, and then converts the mechanical resonance into an electrical signal output using the piezoelectric effect. FBAR mainly uses the longitudinal piezoelectric coefficient (d33) of the piezoelectric film to generate the piezoelectric effect, so its main working mode is the longitudinal wave mode in the thickness direction (Thickness Extensional Mode, abbreviated as TE mode).

[0005] Ideally, a thin film bulk acoustic resonator only excites the thickness direction (TE) mode, but in addition to the desired TE mode, there are also transverse parasitic modes such as Rayleigh-Lamb modes and mechanical waves perpendicular to the direction of the TE mode. These transverse mode waves will be lost at the boundaries of the resonator, thereby causing energy loss of the longitudinal mode required by the resonator, ultimately leading to a decrease in the Q value of the resonator.

[0006] In order to inhibit the leakage of the transverse mode acoustic wave at the edge of the resonator, a protruding structure can be arranged along the edge of the effective area of the resonator, so as to confine the transverse mode acoustic wave in the effective area of the resonator, and improve the Q value.

[0007] However, the general protruding structure in the prior art cannot meet the requirement of the device end for high Q value of the resonator. Therefore, the demand for a new structure that can further improve the Q value of the resonator is increasingly urgent. SUMMARY

[0008] To alleviate or solve at least one aspect of the above problems in the prior art, the present application is proposed.

[0009] According to an aspect of an embodiment of the present application, a bulk acoustic wave resonator is provided, comprising:

[0010] a substrate;

[0011] an acoustic mirror;

[0012] a bottom electrode;

[0013] a top electrode; and

[0014] a piezoelectric layer,

[0015] wherein:

[0016] the overlapping area of the top electrode, the piezoelectric layer, the bottom electrode and the acoustic mirror in the thickness direction of the resonator constitutes an effective area of the resonator;

[0017] the top electrode and / or the bottom electrode is / are provided with a protruding structure along the effective area, the protruding structure comprises a first protruding layer and a second protruding layer, the first protruding layer is arranged adjacent to the piezoelectric layer, the outer end of the second protruding layer is away from the piezoelectric layer in the thickness direction of the resonator and is stacked with the first protruding layer, the part of the first protruding layer and the second protruding layer that are stacked with each other constitutes a stacking part;

[0018] the protruding structure is provided with a single layer part on the inner side of the stacking part, the single layer part is arranged between the corresponding electrode and the piezoelectric layer; and

[0019] the ratio of the thickness of the single layer part to the thickness of the stacking part is not greater than 0.62.

[0020] Embodiments of the present application also relate to a manufacturing method of a bulk acoustic wave resonator, the bulk acoustic wave resonator comprising a substrate, an acoustic mirror, a bottom electrode, a top electrode and a piezoelectric layer, the overlapping area of the top electrode, the piezoelectric layer, the bottom electrode and the acoustic mirror in the thickness direction of the resonator constitutes an effective area of the resonator, the method comprising the steps of:

[0021] A convex structure is formed in the effective region along the bottom electrode and / or the top electrode, the convex structure includes a first convex layer and a second convex layer, the first convex layer is arranged adjacent to the piezoelectric layer, the outer end of the second convex layer is away from the piezoelectric layer in the thickness direction of the resonator and is stacked with the first convex layer, the part where the first convex layer and the second convex layer are stacked with each other constitutes a stacking part, a single layer part is provided inside the stacking part of the convex structure, the single layer part is provided between the corresponding electrode and the piezoelectric layer,

[0022] wherein:

[0023] The method includes selecting the thickness of the single layer part and the thickness of the stacking part so that the ratio of the two is not greater than 0.62.

[0024] Embodiments of the present application also relate to an electronic device including the above-mentioned filter or the above-mentioned resonator.

[0025] Embodiments of the present application also relate to an electronic device including the above-mentioned filter or the above-mentioned resonator. BRIEF DESCRIPTION OF DRAWINGS

[0026] The following description and drawings can better help understand these and other features and advantages of the various embodiments disclosed by the present application, in which the same reference signs always represent the same components, in which:

[0027] Figure 1 is a cross-sectional view of a bulk acoustic wave resonator according to an exemplary embodiment of the present application;

[0028] Figure 2 is a graph showing the relationship between the width (unit: μm) of the single layer part of the convex structure of the resonator and the parallel resonance impedance Rp (unit: ohm) of the resonator when the resonant frequency of the resonator is 1.5 GHz-2.8 GHz, and the case of frequency band B25 is exemplarily shown when the width of the stacking part is fixed;

[0029] Figure 3 is a graph showing the maximum value of the parallel resonance impedance Rp of the resonator when H1 is H2 is is a graph showing the maximum value of the parallel resonance impedance Rp of the resonator when H1 is H2 is ;

[0030] Figure 4 are two Smith charts, the left chart exemplarily shows the Smith chart in the case of point 1 in Figure 2 , and the right chart exemplarily shows the Smith chart in the case of point 3 in Figure 2 ;

[0031] Figure 5 A graph showing the relationship between the width (unit: μm) of the single layer portion of the protruding structure of the resonator and the parallel resonant impedance Rp (unit: ohm) of the resonator when the width of the laminated portion is fixed, in the case of frequency band B3, when the resonant frequency of the resonator is 1.5 GHz to 2.8 GHz, is shown as an example;

[0032] Figure 6 Three Smith charts are shown, the left chart shows the Smith chart in the case of point 1 in Figure 5 , the middle chart shows the Smith chart in the case of point 2 in Figure 5 , and the right chart shows the Smith chart in the case of point 3 in Figure 5 ;

[0033] Figure 7 A graph showing the relationship between the width (unit: μm) of the single layer portion of the protruding structure of the resonator and the parallel resonant impedance Rp (unit: ohm) of the resonator when the width of the laminated portion is fixed, in the case of frequency band Bl, when the resonant frequency of the resonator is 1.5 GHz to 2.8 GHz, is shown as an example;

[0034] Figure 8 Three Smith charts are shown, the left chart shows the Smith chart in the case of point 1 in Figure 7 , the middle chart shows the Smith chart in the case of point 2 in Figure 7 , and the right chart shows the Smith chart in the case of point 3 in Figure 7 ;

[0035] Figure 9 A cross-sectional view of a bulk acoustic wave resonator according to another example embodiment of the present application;

[0036] Figures 10A-10G A series of structural views showing the manufacturing process of the bulk acoustic wave resonator shown in Figure 1 is shown as an example. DETAILED DESCRIPTION

[0037] The technical solutions of the present application will be further described below by way of examples in conjunction with the accompanying drawings. In the description, identical or similar reference numerals indicate identical or similar components. The following description of the embodiments of the present application with reference to the accompanying drawings is intended to explain the general inventive concept of the present application, and should not be construed as limiting the present application to one of the embodiments. The present application is described by way of a part of the embodiments, but not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art belong to the scope of protection of the present application.

[0038] Figure 1A cross-sectional schematic view of a bulk acoustic wave resonator according to an exemplary embodiment of the present application.

[0039] Reference numerals in the present application are explained as follows:

[0040] 10: substrate, which can be made of single crystal silicon, gallium nitride, gallium arsenide, sapphire, quartz, silicon carbide, diamond, etc.

[0041] 20: acoustic mirror, which can be a cavity, or can be a Bragg reflection layer or other equivalent form. In the embodiment shown in the present application, a cavity is used.

[0042] 30: bottom electrode, which can be made of molybdenum, ruthenium, gold, aluminum, magnesium, tungsten, copper, titanium, iridium, osmium, chromium, or a composite of the above metals or an alloy thereof, etc.

[0043] 40: piezoelectric layer, which can be made of a single crystal piezoelectric material, such as single crystal aluminum nitride, single crystal gallium nitride, single crystal lithium niobate, single crystal lead zirconate titanate (PZT), single crystal potassium niobate, single crystal quartz thin film, or single crystal lithium tantalate, etc., or a polycrystalline piezoelectric material (as opposed to a single crystal material, a non-single crystal material), such as polycrystalline aluminum nitride, zinc oxide, PZT, etc., or a rare earth element doped material containing the above materials in a certain atomic ratio, such as doped aluminum nitride, which contains at least one rare earth element, such as scandium (Sc), yttrium (Y), magnesium (Mg), titanium (Ti), lanthanum (La), cerium (Ce), praseodymium (Pr), neodymium (Nd), promethium (Pm), samarium (Sm), europium (Eu), gadolinium (Gd), terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb), and lutetium (Lu).

[0044] 50: top electrode, which can be made of the same material as the bottom electrode, such as molybdenum, ruthenium, gold, aluminum, magnesium, tungsten, copper, titanium, iridium, osmium, chromium, or a composite of the above metals or an alloy thereof, etc. The material of the top electrode and the bottom electrode is generally the same, but can also be different.

[0045] 52: first protruding layer, which can be made of molybdenum, ruthenium, gold, aluminum, magnesium, tungsten, copper, titanium, iridium, osmium, chromium, or a composite of the above metals or an alloy thereof, etc., and can be made of the same material as the corresponding electrode or a different material. The first protruding layer can also be made of a non-metallic material, such as silicon oxide, silicon carbide, silicon nitride, aluminum nitride, or an oxide of the above metals, etc.

[0046] 53: Second Protrusion Layer. The material of the second protrusion layer can be molybdenum, ruthenium, gold, aluminum, magnesium, tungsten, copper, titanium, iridium, osmium, chromium, or a composite or alloy of the above metals, etc., and its material can be the same as or different from the material of the corresponding electrode. The second protrusion layer can also be a non-metallic material, such as silicon oxide, silicon carbide, silicon nitride, aluminum nitride, or oxides of the above metals, etc. The materials of the first protrusion layer and the second protrusion layer can be the same or different. Under different circumstances, the acoustic impedance of the materials of the first protrusion layer and the second protrusion layer is different.

[0047] 70: Process layer, which can cover the top electrode, can be a quality-conditioning load layer or a passivation layer. The material of the process layer can be a dielectric material, such as silicon dioxide, aluminum nitride, silicon nitride, etc.

[0048] The above description of the reference numerals applies to various embodiments of the present invention.

[0049] like Figure 1 As shown, the top electrode 50 has a protruding structure along the effective region of the resonator. This protruding structure includes a first protruding layer 52 and a second protruding layer 53. The first protruding layer 52 is arranged adjacent to the piezoelectric layer 40. Here, "adjacent to the piezoelectric layer 40" means that when it is disposed on the top electrode 50, it is adjacent to or adjacent to the piezoelectric layer 40, and there is no second protruding layer between the first protruding layer and the piezoelectric layer. The second protruding layer 53 is located at the outer end of the second protruding layer 53 (at...). Figure 1 In, such as Figure 1 As shown on the left, the portion of the top electrode (either at the edge or near the edge) is positioned away from the piezoelectric layer 40, as shown in the image. Figure 1 As shown, "away from the piezoelectric layer" here means that, in the case of the top electrode, there is a first protrusion layer between it and the piezoelectric layer. Figure 1 In the middle, the outer end of the second protruding layer 53 is stacked with the first protruding layer 52 in the thickness direction of the resonator, and the stacked portion forms a stacked part (in Figure 1 (The region corresponding to L).

[0050] It should be noted that "far from" and "near" are only used to indicate the positional relationship of the second protrusion layer 53 and the first protrusion layer 52 relative to the piezoelectric layer 40 in the thickness direction of the resonator for the stacked portion.

[0051] like Figure 1 As shown, the second protruding layer 53 also includes a portion located inside the stacked portion, namely, a single-layer portion (in Figure 1 (The region corresponding to I).

[0052] exist Figure 1In the example shown, the single-layer portion is a part of the second raised layer 53. However, the invention is not limited to this; for example, as described later with reference to Figure 10, the single-layer portion is a part of the first raised layer 52. Furthermore, as those skilled in the art will understand, the single-layer portion may not be a part of the first or second raised layer, but rather a third portion independent of the first raised layer 52 and the second raised layer 53, except that the outer side of this third portion is connected to the inner side of the stacked portion and that this third portion is adjacent to or disposed between the corresponding electrode and the piezoelectric layer. These are all within the scope of protection of the present invention.

[0053] like Figure 1 As shown, the first protruding layer 52 has a thickness H1, and the second protruding layer 53 has a thickness H2. As those skilled in the art will understand, the thickness of the stacked portion is the sum of H1 and H2. In the case where the second protruding layer 53 constitutes the single-layer portion described above, the thickness of the single-layer portion is H2.

[0054] like Figure 1 As shown, L corresponds to the width of the stacked portion, while I corresponds to the width of the single-layer portion, that is, in Figure 1 The extension length of the second protruding layer 53 extending to the inner side of the inner end of the first protruding layer 52.

[0055] It should be noted that in this invention, for the structure with double protrusions, H2 / (H1+H2) should not be greater than 0.62. This is beneficial to improving the parallel resonant impedance of the resonator, thereby improving the performance of the resonator.

[0056] Figure 2 For example, when the resonant frequency is 1.5GHz-2.8GHz, taking band B25 (whose transmit frequency is 1.850-1.915GHz and receive frequency is 1.930-1.995GHz) as an example, the relationship between the width of the single layer of the protrusion structure of the resonator (in μm) and the parallel resonant impedance Rp (in ohms) of the resonator is shown. Figure 2 In the diagram, the dashed line represents the case where H2 / (H1+H2) = 0.7, while the solid line corresponds to the case where H2 / (H1+H2) = 0.3. The solid line shows two high points, point 1 and point 2, with respect to the parallel resonant impedance Rp, while the dashed line shows one high point, point 3, with respect to the parallel resonant impedance Rp. The thickness (H1+H2) of the overlapping portion corresponding to the dashed and solid lines is the same.

[0057] from Figure 2It can be seen that, at the points 1 and 2 corresponding to the case of H2 / (H1+H2)=0.3, the parallel resonance impedance Rp of the resonator is approximately between 4600 ohms and 4700 ohms, which is greater than the value of the parallel resonance impedance Rp at the point 3, which is the highest point corresponding to the case of H2 / (H1+H2)=0.7. Therefore, in the B25 frequency band, when H2 / (H1+H2)=0.3, the parallel resonance impedance Rp has two high points with the change of the width of the single-layer portion of the protruding structure when the width of the superposition portion is fixed, which not only can improve the parallel resonance impedance Rp of the resonator, but also can improve the degree of freedom of design.

[0058] Figure 3 It is exemplarily shown that, when the resonant frequency of the resonator is 1.5 GHz-2.8 GHz, in the case of the frequency band B25, the maximum value of the parallel resonance impedance Rp of the resonator in the structure shown in Figure 1 is when H1 is and H2 is , and the maximum value of the parallel resonance impedance Rp of the resonator in the structure shown in is when H1 is

[0059] and H2 is Figure 3 . It is exemplarily shown that, when the resonant frequency of the resonator is 1.5 GHz-2.8 GHz, in the case of the frequency band B25, the maximum value of the parallel resonance impedance Rp of the resonator in the structure shown in is 4600 ohms when the thickness of H1 is and the thickness of H2 is , and the maximum value of the parallel resonance impedance Rp of the resonator in the structure shown in

[0060] is about 4400 ohms when the thickness of H1 is Figure 2 and the thickness of H2 is Figure 4 .

[0061] Figure 4 It is exemplarily shown that, when the resonant frequency of the resonator is 1.5 GHz-2.8 GHz, in the case of the frequency band B25, the maximum value of the parallel resonance impedance Rp of the resonator in the structure shown in Figure 2 is Figure 2 when the width of the single-layer portion of the protruding structure is about 1.25 μm at the point 1, and the width of the single-layer portion of the protruding structure is about 3.4 μm at the points 2 and 3. Figure 4 It can be seen that, as shown in the left side of the figure, the sub-resonance is small; and as shown in the right side of the figure, the sub-resonance is large.Figure 4 As shown in the right side of the figure, in Figure 4 the position indicated by A1 in the right side of the figure, the sub-resonance is larger.

[0062] In the above embodiments, the present application is exemplarily described with the frequency band B25 as an example, when the resonance frequency of the resonator is 1.5GHz-2.8GHz.

[0063] It should be noted that, in the case of the frequency band B1 (its transmission frequency is 1.920-1.980GHz, and its reception frequency is 2.110-2.170GHz) as an example, when the resonance frequency of the resonator is 1.5GHz-2.8GHz, and in the case of the frequency band B3 (its transmission frequency is 1.710-1.785GHz, and its reception frequency is 1.805-1.880GHz) as an example, similar situations as the previous embodiments still exist.

[0064] Figure 5 The relationship between the width (unit: μm) of the single layer part of the convex structure of the resonator and the parallel resonance impedance Rp (unit: ohm) of the resonator when the width of the laminated part is fixed, in the case of the frequency band B3 as an example, when the resonance frequency of the resonator is 1.5GHz-2.8GHz, is exemplarily shown in the right side of the figure. In Figure 5 , the short interval dotted line is for the case of H2 / (H1+H2)=0.31, the solid line is for the case of H2 / (H1+H2)=0.54, and the long interval dotted line is for the case of H2 / (H1+H2)=0.69, the short interval dotted line shows two high points point 1 and point 2 of the parallel resonance impedance, and the long interval dotted line shows one high point point 3 of the parallel resonance impedance, the (H1+H2) values of the laminated part corresponding to the long interval dotted line, the short interval dotted line and the solid line are the same.

[0065] Figure 5 The corresponding structure corresponds to Figure 1 , from Figure 5 It can be seen that, under the B3 frequency band, with the increase of the H2 thickness of the single layer part, its periodicity becomes less and less obvious, and the parallel resonance impedance Rp also has a certain amplitude of decrease, which again reflects that the thickness H2 of the single layer part and the size of the parallel resonance impedance Rp have obvious correlation.

[0066] In Figure 5In the B3 band, the parallel resonance impedance Rp values in the case of H2 / (H1+H2) = 0.31 and H2 / (H1+H2) = 0.54 are basically higher than the parallel resonance impedance Rp values in the case of H2 / (H1+H2) = 0.69. In addition, in the B3 band, the parallel resonance impedance Rp has two high points with the change of the width of the single layer part of the protruding structure in the case of H2 / (H1+H2) = 0.31 compared with the case of H2 / (H1+H2) = 0.69, which not only can improve the parallel resonance impedance Rp of the resonator, but also can improve the design freedom.

[0067] Figure 6 Three Smith charts are shown, the left chart exemplarily shows the Smith chart in the case of point 1 in Figure 5 , the middle chart exemplarily shows the Smith chart in the case of point 2 in Figure 5 , and the right chart exemplarily shows the Smith chart in the case of point 3 in Figure 5 . It can be seen that the left chart has the minimum sub-resonance, while the middle chart and the right chart have larger sub-resonance at the position indicated by A1. Therefore, if the same parallel resonance impedance Rp value is selected, the sub-resonance increases in turn with the increase of the thickness H2 of the single layer part, so a small thickness H2 should be selected.

[0068] Figure 7 The relationship between the width (unit: μm) of the single layer part of the protruding structure of the resonator and the parallel resonance impedance Rp (unit: ohm) of the resonator when the resonant frequency of the resonator is 1.5 GHz-2.8 GHz and the width of the laminated part is fixed is exemplarily shown in the case of the frequency band B1. Figure 7 In the B1 band, the solid line is the case of H2 / (H1+H2) = 0.23, the long-interval dashed line is the case of H2 / (H1+H2) = 0.62, and the short-interval dashed line is the case of H2 / (H1+H2) = 0.77, the solid line shows a high point point 1 of the parallel resonance impedance, the long-interval dashed line shows a high point point 2 of the parallel resonance impedance, and the short-interval dashed line shows a high point point 3 of the parallel resonance impedance, the laminated part thickness (H1+H2) values corresponding to the solid line, the long-interval dashed line and the short-interval dashed line are the same.

[0069] Figure 7 The corresponding structure corresponds to Figure 1 , in the case of Figure 7In the B1 band, it can be seen that as the thickness H2 of the single-layer part increases, the parallel resonance impedance Rp exhibits two characteristics: 1. The parallel resonance impedance Rp value gradually decreases; 2. The first cycle becomes less and less obvious, and when H2 / (H1+H2) = 0.77, the first cycle has disappeared, and the resonator will only have a high point in the second cycle. Therefore, in order to use the high point of the parallel resonance impedance Rp, when the thickness H2 is three, the points 1, 2 and 3 in Figure 7 need to be selected.

[0070] In the B1 band, it can be seen that as the thickness H2 of the single-layer part increases, the parallel resonance impedance Rp exhibits two characteristics: 1. The parallel resonance impedance Rp value gradually decreases; 2. The first cycle becomes less and less obvious, and when H2 / (H1+H2) = 0.77, the first cycle has disappeared, and the resonator will only have a high point in the second cycle. Therefore, in order to use the high point of the parallel resonance impedance Rp, when the thickness H2 is three, the points 1, 2 and 3 in Figure 7 need to be selected.

[0071] Figure 8 Three Smith charts are shown, the left chart exemplarily shows the Smith chart in the case of point 1 in Figure 7 , the middle chart exemplarily shows the Smith chart in the case of point 2 in Figure 7 , and the right chart exemplarily shows the Smith chart in the case of point 3 in Figure 7 . It can be seen from Figure 8 that if the high value of the parallel resonance impedance Rp is selected for each thickness H2 of the single-layer part, as the thickness H2 increases, the sub-resonance increases in turn, so a small thickness H2 should be selected. Although the sub-resonance of point 1 and point 2 is basically the same, the parallel resonance impedance Rp value of point 2 is smaller than that of point 1.

[0072] It can be seen from Figure 2 , 5 , 7 that when the ratio of the thickness of the single-layer part to the thickness of the superposed part is at a low value, such as 0.23, 0.3, 0.54, 0.62, the resonator has a higher high point of the parallel resonance impedance Rp, and when the ratio of the thickness of the single-layer part to the thickness of the superposed part is at a high value, such as 0.69, 0.7, 0.77, the resonator has a lower high point of the parallel resonance impedance Rp. In addition, it can be seen from Figures 5-8It can be seen that, as the thickness of the single-layer portion increases, the high point of the parallel resonance impedance Rp value is no longer obvious when the width of the single-layer portion is small. In order to obtain a higher parallel resonance impedance Rp value, a wider single-layer portion needs to be selected, thus having to face a higher sub-resonance effect.

[0073] Correspondingly, in the present application, the ratio of the thickness of the single-layer portion to the thickness of the stacked portion is selected to be no greater than 0.62, and in a further embodiment, is within the range of 0.2-0.55.

[0074] In the present application, in one embodiment, the width of the single-layer portion is selected to be within the range of 0.2 μm-7 μm. As can be understood by those skilled in the art, based on different widths of the stacked portion and the selection of different high points of the parallel resonance impedance Rp, the width of the single-layer portion can be selected within the range of 0.2 μm-7 μm.

[0075] In Figure 1 the embodiment shown, the first protruding layer 52 is completely covered by the second protruding layer 53, and the second protruding layer 53 also comprises the single-layer portion. Figure 9 Then, unlike the structure shown in Figure 1 , in Figure 9 , the width of the first protruding layer 52 is greater than the width of the second protruding layer 53. As can be seen from Figure 9 , the second protruding layer 53 only covers a portion of the first protruding layer 52. Figure 9 The L corresponding region in corresponds to the aforementioned stacked portion, and the portion of the first protruding layer 52 inside the stacked portion (i.e. the I corresponding region) constitutes the single-layer portion.

[0076] Figure 9 In the structure shown in , the thickness of the single-layer portion is denoted by Hl, and the thickness of the stacked portion is still denoted by (Hl+H2).

[0077] Figure 9 The embodiment shown in Figure 1 can also achieve the similar technical effects of the embodiment shown in , which will not be described herein again.

[0078] Figures 10A-10G The following will refer to Figure 1 to exemplarily illustrate the manufacturing process of the bulk acoustic wave resonator shown in .

[0079] Step 1: As shown in Figure 10A , a cavity (corresponding to the acoustic mirror cavity 20) is formed on the substrate 10 by using an ion etching process, and a sacrificial material layer (not shown) is filled therein, with the upper surface of the sacrificial material layer being flush with the upper surface of the substrate 10.

[0080] Step 2: As shown in Figure 10B , the first protruding layer 52 is formed on the sacrificial material layer.As shown, a metal layer is deposited on the surface of the substrate 10 and the sacrificial material layer by sputtering or vapor deposition, and the bottom electrode 30 is formed by patterning the metal layer by photolithography and etching.

[0081] Step 3: As Figure 10C As shown, a piezoelectric material layer is deposited on the surface of the substrate 10 and the bottom electrode 30 to form a piezoelectric layer 40.

[0082] Step 4: As Figure 10D As shown, in Figure 10C A metal layer is deposited on the upper surface of the piezoelectric layer 40 using a sputtering or evaporation process, and a first protrusion layer 52 is formed by patterning the metal layer using photolithography and etching processes. The first protrusion layer 52 has a thickness H1. As those skilled in the art will understand, the material of the first protrusion layer 52 can also be a non-metallic material.

[0083] Step 5: As Figure 10E As shown, in Figure 10D A metal layer is deposited on the upper surface of the piezoelectric layer 40 and the upper surface of the first protrusion layer 52 using a sputtering or evaporation process, and then patterned using photolithography and etching processes to form a second protrusion layer 53. As those skilled in the art will understand, the thickness of the second protrusion layer 53 can also be a non-metallic material. Figure 10E As shown, a portion of the second raised layer 53 (the portion within region L, i.e., the portion corresponding to the stacked portion) covers the first raised layer 52, and another portion (the portion within region I, i.e., the portion corresponding to the monolayer portion) covers the piezoelectric layer 40. At least one monolayer portion of the second raised layer 53 has a thickness H2. In step 5 above, the second raised layer 53 is formed on the first raised layer 52 and the piezoelectric layer 40, and the final second raised layer 53 covers the first raised layer 52 and partially covers the piezoelectric layer 40. The second raised layer 53 includes the monolayer portion. In step 5, H2 / (H1+H2) is not greater than 0.62.

[0084] Step 6: As Figure 10F As shown, in Figure 10E A metal layer is deposited on the upper surface of the structure shown, and the metal layer is patterned into a top electrode 50.

[0085] Step 7: As Figure 10G As shown, in Figure 10F The structure shown has a passivation layer 70 formed by applying a patterned passivation layer material to its upper surface, followed by releasing the sacrificial material layer within the acoustic mirror cavity, thereby forming a passivation layer 70. Figure 1 The structure shown.

[0086] It should be noted that the top electrode 50 and the passivation layer 70 can also be formed in a single photolithography step. Correspondingly, in step 6, in... Figure 10EThe upper surface of the structure shown is deposited with a layer of a metal material as a top electrode 50, and a layer of passivation material is formed on the metal layer; in step 7, a photolithography is performed on the passivation material layer and the metal material layer to pattern the passivation layer and the top electrode, and then the sacrificial material layer in the acoustic mirror cavity is released, thereby forming a structure as shown in Figure 1 .

[0087] In the above steps 1-7 for manufacturing the structure shown in Figure 1 , the first protruding layer and the second protruding layer are formed by etching.

[0088] In the above steps 1-7 for manufacturing the structure shown in Figure 9 , the first protruding layer and the second protruding layer are formed by etching. Figure 9

[0089] In the above embodiments, the first protruding layer and the second protruding layer are both disposed at the top electrode along the effective area of the resonator, but the present application is not limited thereto. For example, the first protruding layer and the second protruding layer can also be disposed at the bottom electrode along the effective area, or can be disposed at both the top electrode and the bottom electrode. These are all within the protection scope of the present application.

[0090] The above steps describe the protruding structure disposed at the top electrode along the effective area, but as those skilled in the art can understand, in the case of the protruding structure disposed at the bottom electrode along the effective area, only the corresponding steps are placed before the steps of Figures 10D-10E , and after the steps of Figure 10B . Figure 10A

[0091] Based on the above, in the process of manufacturing the bulk acoustic wave resonator based on the present application, the following steps are included:

[0092] The protruding structure is formed along the effective area at the bottom electrode and / or the top electrode, the protruding structure includes a first protruding layer and a second protruding layer, the first protruding layer is arranged adjacent to the piezoelectric layer, the outer end of the second protruding layer is away from the piezoelectric layer in the thickness direction of the resonator and is stacked with the first protruding layer, the part of the first protruding layer and the second protruding layer that are stacked with each other constitutes a stacking part, the protruding structure is provided with a single layer part on the inner side of the stacking part, the single layer part is arranged between the corresponding electrode and the piezoelectric layer, wherein: the method includes selecting the thickness of the single layer part and the thickness of the stacking part, so that the ratio of the two is not greater than 0.62.

[0093] ​​It should be noted that in the present application, each numerical range, except for the case where it is explicitly stated that the end point value is not included, can be the median value of each numerical range, in addition to the end point value, which is within the protection scope of the present application.

[0094] In the present application, up and down are relative to the bottom surface of the substrate of the resonator, the side of a component close to the bottom surface is the lower side, and the side away from the bottom surface is the upper side.

[0095] In the present application, inner and outer are relative to the center of the effective area (the overlapping area of the piezoelectric layer, the top electrode, the bottom electrode and the acoustic mirror in the thickness direction of the resonator constitutes the effective area) of the resonator (i.e. the center of the effective area) in the lateral direction or the radial direction, the side or the end of a component close to the center of the effective area is the inner side or the inner end, and the side or the end of the component away from the center of the effective area is the outer side or the outer end. For a reference position, the inner side of the position means between the position and the center of the effective area in the lateral direction or the radial direction, and the outer side of the position means farther away from the center of the effective area than the position in the lateral direction or the radial direction.

[0096] As those skilled in the art can understand, the bulk acoustic wave resonator according to the present application can be used to form a filter or an electronic device. The electronic device herein includes, but is not limited to, intermediate products such as radio frequency front end, filter amplification module, and terminal products such as mobile phone, WIFI, and unmanned aerial vehicle.

[0097] Based on the above, the present application proposes the following technical solutions:

[0098] 1. A bulk acoustic wave resonator, comprising:

[0099] a substrate;

[0100] an acoustic mirror;

[0101] a bottom electrode;

[0102] a top electrode; and

[0103] a piezoelectric layer,

[0104] wherein:

[0105] the overlapping area of the top electrode, the piezoelectric layer, the bottom electrode and the acoustic mirror in the thickness direction of the resonator constitutes the effective area of the resonator;

[0106] the top electrode and / or the bottom electrode is provided with a protruding structure along the effective area, the protruding structure comprises a first protruding layer and a second protruding layer, the first protruding layer is arranged adjacent to the piezoelectric layer, the outer end of the second protruding layer is away from the piezoelectric layer in the thickness direction of the resonator and is stacked with the first protruding layer, the part of the first protruding layer and the second protruding layer stacked with each other constitutes a stacking part;

[0107] The protruding structure is provided with a single layer portion on the inner side of the laminated portion, the single layer portion being provided between the corresponding electrode and the piezoelectric layer; and

[0108] The ratio of the thickness of the single layer portion to the thickness of the laminated portion is not more than 0.62.

[0109] 2. The resonator according to claim 1, wherein:

[0110] The single layer portion is a part of the second protruding layer.

[0111] 3. The resonator according to claim 1, wherein:

[0112] The single layer portion is a part of the first protruding layer.

[0113] 4. The resonator according to claim 1, wherein:

[0114] The width of the single layer portion is in the range of 0.2 μm to 7 μm.

[0115] 5. The resonator according to claim 1, wherein:

[0116] The first protruding layer and the second protruding layer are made of the same material.

[0117] 6. The resonator according to claim 5, wherein:

[0118] The material of the first protruding layer and the second protruding layer is selected from molybdenum, ruthenium, gold, aluminum, magnesium, tungsten, copper, titanium, iridium, osmium, chromium, or a composite of the above metals or an alloy thereof.

[0119] 7. The resonator according to claim 1, wherein:

[0120] The first protruding layer and the second protruding layer are made of different materials, and the material of the first protruding layer and the material of the second protruding layer have different acoustic impedances.

[0121] 8. The resonator according to claim 1, wherein:

[0122] The ratio is in the range of 0.1 to 0.6.

[0123] 9. The resonator according to claim 8, wherein:

[0124] The ratio is in the range of 0.2 to 0.55.

[0125] 10. The resonator according to any one of claims 1 to 9, wherein:

[0126] The frequency of the resonator is in the range of 1.5 GHz to 2.8 GHz.

[0127] 11. The resonator according to claim 10, wherein:

[0128] the resonator operates in a frequency band of B25, and the thickness of the single-layer portion is in a range of 0.5 to 1.5 μm; or

[0129] the resonator operates in a frequency band of B3, and the thickness of the single-layer portion is in a range of 0.5 to 1.5 μm; or

[0130] the resonator operates in a frequency band of B1, and the thickness of the single-layer portion is in a range of 0.5 to 1.5 μm.

[0131] 12. The resonator according to claim 1, wherein:

[0132] the protruding structure is provided at a non-electrode connection end of the corresponding electrode; and / or

[0133] the protruding structure is provided at an electrode connection end of the corresponding electrode.

[0134] 13. A method of manufacturing a bulk acoustic wave resonator including a substrate, an acoustic mirror, a bottom electrode, a top electrode, and a piezoelectric layer, a coincident region of the top electrode, the piezoelectric layer, the bottom electrode, and the acoustic mirror in a thickness direction of the resonator constituting an effective region of the resonator, the method comprising the steps of:

[0135] forming a protruding structure at the bottom electrode and / or the top electrode along the effective region, the protruding structure including a first protruding layer and a second protruding layer, the first protruding layer being disposed adjacent to the piezoelectric layer, an outer end of the second protruding layer being away from the piezoelectric layer in the thickness direction of the resonator and being superposed with the first protruding layer, a portion where the first protruding layer and the second protruding layer are superposed with each other constituting a superposed portion, the protruding structure being provided with a single-layer portion at an inner side of the superposed portion, the single-layer portion being provided between the corresponding electrode and the piezoelectric layer,

[0136] wherein:

[0137] the method includes selecting the thickness of the single-layer portion and the thickness of the superposed portion such that the ratio of the two is not more than 0.62.

[0138] 14. The method according to claim 13, wherein:

[0139] the method includes the steps of forming the first protruding layer on the piezoelectric layer, and forming the second protruding layer on the first protruding layer and the piezoelectric layer, the second protruding layer covering the first protruding layer and covering a portion of the piezoelectric layer, the second protruding layer including the single-layer portion.

[0140] 15. The method according to claim 13, wherein:

[0141] ​​​The method includes the steps of forming a first protrusion layer on the piezoelectric layer, and forming a second protrusion layer on the first protrusion layer and the piezoelectric layer, the second protrusion layer covering only the outer end of the first protrusion layer, the first protrusion layer including the single layer portion.

[0142] 16. A filter comprising the bulk acoustic resonator of any one of claims 1-12.

[0143] 17. An electronic device comprising the filter of claim 16, or the bulk acoustic resonator of any one of claims 1-12.

[0144] While embodiments of the application have been shown and described, it is to be understood that the embodiments described are only by way of example and that changes can be made to those embodiments without departing from the spirit and scope of the application as defined by the appended claims and their equivalents.

Claims

1. A bulk acoustic resonator, comprising: Base; Acoustic mirror; Bottom electrode; Top electrode; and piezoelectric layer in: The overlapping region of the top electrode, piezoelectric layer, bottom electrode, and acoustic mirror in the thickness direction of the resonator constitutes the effective region of the resonator; The top electrode and / or bottom electrode are provided with a protrusion structure along the effective area. The protrusion structure includes a first protrusion layer and a second protrusion layer. The first protrusion layer is arranged adjacent to the piezoelectric layer. The outer end of the second protrusion layer is away from the piezoelectric layer in the thickness direction of the resonator and is superimposed on the first protrusion layer. The portion of the first protrusion layer and the second protrusion layer superimposed on each other constitutes a superimposed portion. The protruding structure has a single-layer portion disposed on the inner side of the stacked portion, and the single-layer portion is disposed between the corresponding electrode and the piezoelectric layer; and The ratio of the thickness of the single layer to the thickness of the stacked layer is no greater than 0.62, so as to improve the parallel resonant impedance.

2. The resonator according to claim 1, wherein: The single-layer portion is part of the second protruding layer.

3. The resonator according to claim 1, wherein: The single-layer portion is part of the first protruding layer.

4. The resonator according to claim 1, wherein: The width of the single-layer portion is in the range of 0.2μm-7μm.

5. The resonator according to claim 1, wherein: The first raised layer and the second raised layer are made of the same material.

6. The resonator according to claim 5, wherein: The materials of the first and second raised layers are selected from molybdenum, ruthenium, gold, aluminum, magnesium, tungsten, copper, titanium, iridium, osmium, chromium, or composites or alloys of the above metals.

7. The resonator according to claim 1, wherein: The first raised layer and the second raised layer are made of different materials, and the acoustic impedances of the materials of the first raised layer and the second raised layer are different.

8. The resonator according to claim 1, wherein: The ratio is in the range of 0.1-0.

6.

9. The resonator according to claim 8, wherein: The ratio is in the range of 0.2-0.

55.

10. The resonator according to any one of claims 1-9, wherein: The frequency of the resonator is in the range of 1.5GHz-2.8GHz.

11. The resonator according to claim 10, wherein: The resonator operates in the B25 frequency band, and the thickness of the single-layer portion is within... Within the range; or The resonator operates in the B3 frequency band, and the thickness of the single-layer portion is within... Within the range; or The resonator operates in the B1 frequency band, and the thickness of the single-layer portion is within... Within the range.

12. The resonator according to claim 1, wherein: The protruding structure is disposed at the non-electrode connection end of the corresponding electrode; and / or The protruding structure is disposed at the electrode connection end of the corresponding electrode.

13. A method for manufacturing a bulk acoustic resonator, the bulk acoustic resonator comprising a substrate, an acoustic mirror, a bottom electrode, a top electrode, and a piezoelectric layer, wherein the overlapping region of the top electrode, the piezoelectric layer, the bottom electrode, and the acoustic mirror in the thickness direction of the resonator constitutes the effective region of the resonator, the method comprising the steps of: A raised structure is formed along the effective region of the bottom electrode and / or top electrode. The raised structure includes a first raised layer and a second raised layer. The first raised layer is arranged adjacent to the piezoelectric layer. The outer end of the second raised layer is away from the piezoelectric layer in the thickness direction of the resonator and overlaps with the first raised layer. The overlapping portion of the first and second raised layers constitutes a stacked portion. A single-layer portion is provided inside the stacked portion of the raised structure. The single-layer portion is disposed between the corresponding electrode and the piezoelectric layer. in: The method includes selecting the thickness of the single-layer portion and the thickness of the stacked portion such that the ratio of the two is not greater than 0.62, so as to improve the parallel resonant impedance.

14. The method of claim 13, wherein: The method includes the steps of: forming a first protrusion layer on a piezoelectric layer, and forming a second protrusion layer on the first protrusion layer and the piezoelectric layer, wherein the second protrusion layer covers the first protrusion layer and a portion of the piezoelectric layer, and the second protrusion layer includes the monolayer portion.

15. The method according to claim 13, wherein: The method includes the steps of: forming a first protrusion layer on a piezoelectric layer, and forming a second protrusion layer on the first protrusion layer and the piezoelectric layer, wherein the second protrusion layer only covers the outer end of the first protrusion layer, and the first protrusion layer includes the monolayer portion.

16. A filter comprising a bulk acoustic resonator according to any one of claims 1-12.

17. An electronic device comprising the filter of claim 16, or the bulk acoustic resonator of any one of claims 1-12.

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