Bulk acoustic wave resonator, manufacturing method thereof, filter, and electronic device

Abstract

The application relates to a bulk acoustic wave resonator, comprising a substrate; an acoustic mirror; a bottom electrode; a top electrode; and a piezoelectric layer, wherein: an overlapping area of the acoustic mirror, the bottom electrode, the piezoelectric layer and the top electrode in a thickness direction of the resonator constitutes an effective area of the resonator; an edge of the top electrode around the effective area is further provided with a conductive layer, the conductive layer is electrically connected with the top electrode; and at least a part of a bottom surface of an inner end and / or an outer end of the conductive layer is provided with a gap with an upper surface of the top electrode to form a suspended structure. The application also relates to a manufacturing method of the bulk acoustic wave resonator, 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 resonator and a manufacturing method thereof, a filter having the resonator, and an electronic device. BACKGROUND

[0002] With the rapid development of today's wireless communication technology, the application of small portable terminal devices is also increasingly widespread, and thus the demand for high-performance, small-size radio frequency front-end modules and devices is increasingly urgent. In recent years, filter devices such as filters, duplexers, etc. based on, for example, film bulk acoustic resonators (FBAR) are increasingly favored by the market. On the one hand, this is because of their excellent electrical properties such as low insertion loss, steep transition characteristics, high selectivity, high power capacity, strong electrostatic discharge (ESD) resistance, etc., and on the other hand, this is also because of their small size and easy integration.

[0003] However, as the frequency of the resonator continues to increase, the thickness of the top electrode and the bottom electrode of the resonator will gradually decrease, which will make the connection loss of the electrode larger and larger, i.e., the resistance of the electrode increases. The increase in the resistance of the electrode will result in a decrease in the Q value of the resonator. SUMMARY

[0004] To improve the Q value of the resonator in the case where the thickness of the top electrode of the resonator is thin, the present application is proposed.

[0005] According to an aspect of an embodiment of the present application, a bulk acoustic resonator is provided, comprising:

[0006] a substrate;

[0007] an acoustic mirror;

[0008] a bottom electrode;

[0009] a top electrode; and

[0010] a piezoelectric layer,

[0011] wherein:

[0012] an overlapping area of the acoustic mirror, the bottom electrode, the piezoelectric layer and the top electrode in the thickness direction of the resonator constitutes an effective area of the resonator;

[0013] an edge of the top electrode around the effective area is further provided with a conductive layer, and the conductive layer is electrically connected with the top electrode;

[0014] at least a part of the bottom surface of the inner end and / or the outer end of the conductive layer has a gap with the upper surface of the top electrode to form a suspended structure.

[0015] An embodiment of the present invention further relates to a method for manufacturing a bulk acoustic wave resonator, the method comprising the steps of: forming a stacked structure of a bottom electrode, a piezoelectric layer, and a top electrode material layer on a substrate;

[0016] The method further comprises:

[0017] Step 1: forming and patterning a sacrificial layer on the stacked structure;

[0018] Step 2: forming a conductive material layer covering the patterned sacrificial layer and the top electrode material layer, wherein the conductive material layer is electrically connected to the top electrode material layer;

[0019] Step 3: Disposing and patterning a barrier layer on the conductive material layer, wherein an inner end of the patterned barrier layer is located inward of a corresponding outer end of the sacrificial layer in a lateral direction of the resonator;

[0020] Step 4: removing the conductive material layer and the top electrode material layer outside the conductive material layer covered by the patterned barrier layer to form a conductive layer and a top electrode;

[0021] Step 5: releasing the sacrificial layer to form a gap between the bottom surface of the inner end of the conductive layer and the upper surface of the top electrode to form an inner end suspended structure.

[0022] in:

[0023] The resonator includes an acoustic mirror, and the overlapping area of ​​the acoustic mirror, top electrode, piezoelectric layer, and bottom electrode of the resonator in the thickness direction of the resonator forms an effective area of ​​the resonator, and in step 4, the conductive layer is arranged around the edge of the effective area.

[0024] An embodiment of the present invention also relates to a filter comprising the above-mentioned bulk acoustic wave resonator.

[0025] An embodiment of the present invention further relates to an electronic device, comprising the above-mentioned filter or resonator. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The following description and accompanying drawings may better help understand these and other features and advantages of various embodiments disclosed herein, wherein like reference numerals denote like components throughout the drawings, wherein:

[0027] FIG. 1A is a schematic top view of a bulk acoustic wave resonator in the prior art;

[0028] FIG. 1B is a schematic top view of a bulk acoustic wave resonator according to an exemplary embodiment of the present invention;

[0029] FIG. 2 For the FIG. 1Aexemplary cross-sectional view taken along A-A' in

[0030] FIG. 3 is a cross-sectional view taken along B-B' in FIG. 1B exemplary cross-sectional view taken along A-A' in

[0031] FIG. 4 is a cross-sectional view of a bulk acoustic wave resonator in the prior art, wherein the top electrode is provided with a bridge structure and a wing;

[0032] FIG. 5 is a cross-sectional view of a bulk acoustic wave resonator according to an exemplary embodiment of the present application, wherein the top electrode is provided with a bridge structure and a wing, and a conductive layer is provided on the top electrode;

[0033] FIG. 6A and 6B are respectively FIG. 5 are respectively an enlarged view of the connecting side and the non-connecting side of the top electrode in

[0034] FIG. 7-12 exemplary shows FIG. 5 the manufacturing process of the bulk acoustic wave resonator shown in

[0035] FIG. 13-30 are respectively structures of bulk acoustic wave resonators according to variant embodiments of the present application;

[0036] FIG. 31-33 is an exemplary cross-sectional view of a plurality of different embodiments of bulk acoustic wave resonators similar to the one taken along B-B' in FIG. 1B

[0037] exemplary shows FIG. 34-37 the manufacturing process of the resonator shown in FIG. 33 DETAILED DESCRIPTION

[0038] The technical solutions of the present application will be further described in detail below by way of examples, with reference to the accompanying drawings. In the description, identical or similar reference numerals indicate identical or similar components. The following description of the embodiments of the present application with reference to the accompanying drawings is intended to explain the general inventive concept of the present application, and should not be understood as a limitation of the present application. The following description is only one of the embodiments of the present application, and is not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art belong to the scope of protection of the present application.

[0039] First, the reference numerals in the drawings of the present application are explained as follows:

[0040] 101: substrate, which can be monocrystalline silicon, gallium nitride, gallium arsenide, sapphire, quartz, silicon carbide, diamond, etc., or can be a monocrystalline piezoelectric substrate such as lithium niobate, lithium tantalate, potassium niobate, etc.​

[0041] 102: bottom electrode (electrode pin or electrode connecting edge), material can be selected from molybdenum, ruthenium, gold, aluminum, magnesium, tungsten, copper, titanium, iridium, osmium, chromium, or a composite of the above metals or an alloy thereof.

[0042] 103: acoustic mirror, which can be a cavity, or can adopt a Bragg reflection layer and other equivalent forms.

[0043] 104: piezoelectric layer, which can be a single crystal piezoelectric material, which can be selected from, for example, single crystal aluminum nitride, single crystal gallium nitride, single crystal lithium niobate, single crystal lead zirconate titanate (PZT), single crystal potassium niobate, single crystal quartz thin film, or single crystal lithium tantalate, etc. It can also be a polycrystalline piezoelectric material (corresponding to single crystal, non-single crystal material), which can be selected from, for example, polycrystalline aluminum nitride, zinc oxide, PZT, etc. It can also be a rare earth element doped material containing a certain atomic ratio of the above materials, for example, doped aluminum nitride, which contains at least one rare earth element such as scandium (Sc), yttrium (Y), magnesium (Mg), titanium (Ti), lanthanum (La), cerium (Ce), praseodymium (Pr), neodymium (Nd), promethium (Pm), samarium (Sm), europium (Eu), gadolinium (Gd), terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb), and lutetium (Lu).

[0044] 105: top electrode (electrode pin or electrode connecting edge), which can have the same material as the bottom electrode, and the material can be selected from molybdenum, ruthenium, gold, aluminum, magnesium, tungsten, copper, titanium, iridium, osmium, chromium, or a composite of the above metals or an alloy thereof. The material of the top electrode and the bottom electrode is generally the same, but can also be different.

[0045] 106: conductive 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.

[0046] 107: surface dielectric layer of the top electrode, which can be made of AlN, SiN, SiO2, Al2O3.

[0047] 108: air gap above the piezoelectric layer.

[0048] 109: protruding layer above the piezoelectric 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.

[0049] 110: sacrificial layer, which can be made of SiO2, doped silicon dioxide, polycrystalline silicon, amorphous silicon, etc.

[0050] 111: surface dielectric layer of the conductive layer, which can be made of AlN, SiN, SiO2, Al2O3.

[0051] 112 and 112A: Conductive layer sacrificial layer, material can be selected from SiO2, doped silicon dioxide, polysilicon, amorphous silicon and other materials.

[0052] In the present application, the connection loss of the top electrode is reduced by increasing the thickness of the top electrode and making a suitable edge structure, i.e. reducing the connection resistance of the top electrode, while improving the Q value of the resonator.

[0053] FIG. 1A A top view of a conventional resonator structure is shown, FIG. 1B A top view of a bulk acoustic wave resonator according to an exemplary embodiment of the present application is shown. In FIG. 1B In the present application, a conductive layer 106 is added to the top electrode of a conventional resonator, which is arranged only in the edge portion area of the top electrode connection edge and non-connection edge.

[0054] The resonator shown in FIG. 1A is cut along the AA' direction, and its cross-sectional view can be obtained as shown in FIG. 2 . FIG. 2 A sandwich structure of a conventional resonator is shown in , which includes a substrate 101, a bottom electrode 102, an acoustic mirror 103, a piezoelectric layer 104, a top electrode 105, and a top electrode surface dielectric layer 107. As those skilled in the art can understand, the dielectric layer 107 can also not be arranged.

[0055] FIG. 1B The resonator shown in FIG. 3 is cut along the BB' direction, and its cross-sectional view can be obtained as shown in FIG. 3 . In FIG. 2 , a conductive layer 106 and a conductive layer surface dielectric layer 111 are added to the conventional resonator shown in FIG. 2 and FIG. 3 , the overlapping area of the acoustic mirror, bottom electrode, piezoelectric layer and top electrode in the thickness direction of the resonator constitutes the effective area of the resonator. In FIG. 3 , the dimensions of a and b are the width dimensions of the overhanging portion of the conductive layer 106, where a is the width dimension of the overhanging portion at the connection edge of the top electrode, and b is the width dimension of the overhanging portion at the non-connection edge of the top electrode. The values of a and b affect the Q value of the resonator, and are related to the specific thickness of the resonator, and are both greater than the Q value of the conventional resonator. At this time, at the non-connection edge of the top electrode, the contact portion of the conductive layer 106 and the top electrode 105, i.e. FIG. 3 , corresponds to the distance c interval in FIG. 3 , the layer structure is different from the inside layer structure of the resonator, thus generating an acoustic impedance mismatch interface, which is beneficial to the reflection of the transverse acoustic wave at this interface back to the inside of the resonator, thus improving the Q value, while the conductive layer increases the thickness of the local top electrode, thus being beneficial to reducing the overall resistance of the top electrode; on the other hand, the overhanging portion of the conductive layer 106, i.e.The interval corresponding to the middle distance b is equivalent to a cantilever beam structure, which will resonate under the excitation of the acoustic wave in the interval corresponding to the distance c, thereby confining a portion of the acoustic wave energy leaking into the c interval within the suspended structure, further reducing the acoustic wave energy that continues to propagate from the c interval to the outside of the resonator, thereby further improving the Q value. At the connecting edge of the top electrode, the conductive layer 106 is divided into three parts. One part of the conductive layer 106 completely covers the top electrode extension area outside the cavity, thereby reducing the top electrode resistance by increasing the thickness of the top electrode. Another part of the conductive layer 106 contacts the edge of the top electrode inside the cavity, that is, FIG. 3 The function of the interval corresponding to the middle distance o is similar to that of the interval of distance c, and a portion of the conductive layer 106 is a suspended structure, and FIG. 3 The interval corresponding to distance a has a similar effect to that of the interval corresponding to distance b.

[0056] In addition, as mentioned later FIG. 7-12 As described above, when the conductive layer 106 and the top electrode 105 are etched in the same step, the etching of the conductive layer and the top electrode does not use two separate etching processes. Therefore, the etching will not stop at the top electrode 105. If the size of a or b is too small, when etching the top electrode, if there is a deviation in the lithography alignment, the top electrode will be cut off, resulting in the inability to transmit signals and affecting the performance of the resonator. For example, see FIG. 12 During etching, etching will stop at the sacrificial layer 112 in the area above the resonator where there is no photoresist protection, and etching will stop at the piezoelectric layer 104 in the rest of the area. If the alignment is offset during photolithography, the opening above the resonator will straddle the edge of the sacrificial layer 112, and the top electrode will be etched open in the opening outside the sacrificial layer 112, causing the resonator to fail. The values ​​of a and b should not be too large. If they are too large, the suspended portion of the conductive layer 106 may collapse. In addition, excessively large values ​​of a and b may also affect the subsequent frequency adjustment. Taking all factors into consideration, in one embodiment of the present invention, the values ​​of a and b are in the range of 0.2μm-20μm.

[0057] like FIG. 3 As shown, c represents the contact width between the conductive layer and the top electrode at the non-connected edge of the top electrode. The c value should not be too small. If it is too small, the contact area between the conductive layer 106 and the top electrode 105 at the non-connected edge of the top electrode will be small, and the conductive effect will be poor. The c value cannot be too large. If it is too large, the area occupied by the resonator will increase. In addition, an increase in the c value is equivalent to an increase in the parallel capacitance between the top electrode and the bottom electrode, and the electromechanical coupling coefficient of the resonator will become smaller. In an optional embodiment of the present invention, the c value is in the range of 0.2μm-10μm.

[0058] FIG. 3The value o is the lateral distance from the edge of the acoustic mirror 103 to the starting point of the suspended position of the conductive layer 106 at the top electrode connection side. In one embodiment of the present invention, the value o is in the range of 0.2 μm-10 μm.

[0059] FIG. 4 It is a cross-sectional schematic diagram of a BAW resonator in the prior art, wherein the top electrode is provided with a bridge structure and a cantilever. FIG. 4 The sandwich structure of a common resonator is shown, in which the resonator includes an air gap 108 above the piezoelectric layer and a protruding layer 109 above the piezoelectric layer, and comprises a substrate 101, a bottom electrode 102, an acoustic mirror 103, a piezoelectric layer 104, a top electrode 105, a dielectric layer 107 on the surface of the top electrode, an air gap 108 above the piezoelectric layer, and a protruding layer 109 above the piezoelectric layer. FIG. 4 In the case of , the presence of air gaps forms a bridge structure and cantilever of the top electrode. FIG. 2 and FIG. 3 , FIG. 4 The inner edge of the bridge structure and the cantilever further defines the boundary of the effective area, that is, the inner edge of the bridge structure and the cantilever is in FIG. 2 The boundaries of the effective areas in the other embodiments containing bridge structures and / or cantilevers are also subject to the same definition.

[0060] FIG. 5 1 is a schematic cross-sectional view of a bulk acoustic wave resonator according to an exemplary embodiment of the present invention, wherein a top electrode is provided with a bridge structure and a cantilever, and a conductive layer 106 and a dielectric layer 111 on the surface of the conductive layer are provided on the top electrode.

[0061] Will FIG. 5 The left and right sides are divided into area A (corresponding to the connection edge area) and area B (corresponding to the non-connection edge area). Area A and area B are partially enlarged to obtain FIG. 6A and FIG. 6B .exist FIG. 6A and 6B In the figure, d (corresponding to the electrode connection edge) and h (corresponding to the electrode non-connection edge) are the lateral distances between the connection edge of the top electrode and the conductive layer (or the outer edge of the suspended structure) and the inner edge of the air gap above the piezoelectric layer, and this distance is greater than or equal to 0. To avoid collapse of the suspended structure, the values ​​of d and h cannot be too large. In an optional embodiment, the values ​​of d and h are in the range of 0.2μm-10μm. As can be understood, d and h can be the same or different.

[0062] FIG. 6A In the figure, the dimension e is the width dimension of the suspended portion of the conductive layer 106, and FIG. 3 a and b are similar, and their values ​​can be in the range of 0.2μm-20μm. FIG. 6BIn the middle, the size of f is the lateral size of the overhanging part of the conductive layer 106, and similar to the values of a, b, and e mentioned above, f can be in the range of 0.2 μm to 20 μm. FIG. 6B In the middle, the value of g is the width of the connection between the top electrode 105 and the conductive layer 106 at the non-connection edge of the top electrode, and similar to the value of c mentioned above, g can be in the range of 0.2 μm to 10 μm. As mentioned above, FIG. 3 As mentioned above, the introduction of the conductive layer 106 at the non-connection edge of the electrode creates an impedance mismatch interface, which can improve the Q value. However, the improvement is related to the thickness of the conductive layer 106 and the width c of the contact part between the conductive layer 106 and the top electrode. When c is constant, the Q value generally increases first and then decreases with the increase of the thickness of the conductive layer 106. When the thickness of the conductive layer 106 is constant, the Q value generally increases and then decreases periodically with the change of the width c. On the other hand, the thicker the conductive layer 106, the smaller the resistance of the electrode. Therefore, a trade-off needs to be made between the two to select a more appropriate thickness of the conductive layer 106, thereby limiting the further reduction of the electrode loss and the further increase of the Q value. The introduction of the bridge structure and / or the wing structure can make the conductive layer 106 fall outside the effective area, reducing the influence of the thickness of the conductive layer 106 on the Q value of the resonator, so that a more optimal thickness can be selected to further reduce the electrode loss. On the other hand, by setting the protruding structure 109 at the edge of the effective area and selecting appropriate width and thickness of the protruding structure, the Q value can be optimized and improved. The overhanging part of the bridge structure and / or the wing structure and the conductive layer 106 can further form a structure similar to a tuning fork, so that a secondary resonance can be formed, more acoustic wave energy can be confined in the conductive layer 106 and the bridge structure or the wing, and the Q value can be further improved.

[0063] The following will be described with reference to the drawings. FIG. 7-12 Brief Description of Examples FIG. 5 Manufacturing process of the bulk acoustic wave resonator shown.

[0064] First, after the bottom electrode 102 and the piezoelectric layer 104 are made on the substrate, the protruding layer 109 above the piezoelectric layer and the sacrificial layer 110 are made, then the top electrode 105 is deposited, the surface medium layer 107 of the top electrode is deposited, and the sacrificial layer 112 for the overhanging structure of the conductive layer is deposited.

[0065] Secondly, the sacrificial layer 112 is patterned by processes such as gluing, exposure, development, and etching, and the structure shown is obtained. FIG. 8 As shown, the etching of the sacrificial layer 112 stops above the surface medium layer 107 of the top electrode. As shown, FIG. 8 The patterned sacrificial layer is at least partially located in the effective area of the resonator.

[0066] Then, the surface medium layer 107 of the top electrode is etched and patterned by using the sacrificial layer 112 as a barrier layer, and the structure shown is obtained. FIG. 9Structure.

[0067] Then, the conductive layer 106 and the conductive layer surface medium layer 111 are deposited in sequence to obtain the structure as shown in FIG. 10 . The conductive layer 106 is electrically connected with the top electrode 105.

[0068] Next, the conductive layer surface medium layer 111 is processed and patterned by, for example, glue coating, exposure, development and etching to obtain the structure as shown in FIG. 11 . The conductive layer surface medium layer 111 is etched to stop on the conductive layer 106. In FIG. 11 , the conductive layer surface medium layer 111 has a predetermined shape. As shown in FIG. 11 , the inner end of the patterned conductive layer surface medium layer 111 is inside the corresponding outer end of the patterned sacrificial layer 112 in the lateral direction of the resonator.

[0069] Then, the conductive layer 106 is etched with the conductive layer surface medium layer 111 as a barrier layer to obtain the structure as shown in FIG. 12 .

[0070] Finally, the sacrificial layers (including the sacrificial layer 110, the sacrificial layer 112 and the sacrificial layer in the acoustic mirror) are removed by wet etching or the like to obtain the final structure as shown in FIG. 5 .

[0071] It should be noted that the above method is only exemplary. For example, the resonator can not be provided with the suspension wing and the bridge structure, and can not be provided with the protruding structure. For another example, the top electrode surface medium layer 107 can not be provided, and the conductive layer surface medium layer 111 can not be provided, but other patterned material layers can be coated on the conductive layer 106.

[0072] In addition, as can be understood, in the above method, in the case of, for example, taking the conductive layer surface medium layer 111 as a barrier layer, the release of the sacrificial layer 112 does not affect the conductive layer surface medium layer 111 in the process of releasing the sacrificial layer 112 after etching the conductive layer 106.

[0073] FIG. 13-30 The structures of bulk acoustic wave resonators according to variant embodiments of the present application are shown respectively. The following is specifically explained.

[0074] FIG. 13 The embodiment shown is similar to FIG. 3 , except that in FIG. 13 , the included angle between the lower edge of the conductive layer 106 and the inner side surface is an acute angle, while in FIG. 3 , the side surface of the conductive layer 106 is vertical or parallel to the thickness direction of the resonator.

[0075] FIG. 14 The embodiment shown is similar toFIG. 3 The embodiment shown in FIG. 9 is similar to that shown in FIG. 8, except that in FIG. 14 The embodiment shown in FIG. 10 is similar to that shown in FIG. 9, except that in FIG. 3 The embodiment shown in FIG. 11 is similar to that shown in FIG. 10, except that in

[0076] FIG. 15 The embodiment shown in FIG. 12 is similar to that shown in FIG. 11, except that in FIG. 3 The embodiment shown in FIG. 13 is similar to that shown in FIG. 12, except that in FIG. 15 The embodiment shown in FIG. 14 is similar to that shown in FIG. 13, except that in FIG. 3 The embodiment shown in FIG. 15 is similar to that shown in FIG. 14, except that in

[0077] FIG. 16 The embodiment shown in FIG. 16 is similar to that shown in FIG. 15, except that in FIG. 5 The embodiment shown in FIG. 17 is similar to that shown in FIG. 16, except that in FIG. 16 The embodiment shown in FIG. 18 is similar to that shown in FIG. 17, except that in FIG. 5 The embodiment shown in FIG. 19 is similar to that shown in FIG. 18, except that in

[0078] FIG. 17 The embodiment shown in FIG. 20 is similar to that shown in FIG. 19, except that in FIG. 5 The embodiment shown in FIG. 21 is similar to that shown in FIG. 20, except that in FIG. 17 The embodiment shown in FIG. 22 is similar to that shown in FIG. 21, except that in FIG. 5 The embodiment shown in FIG. 23 is similar to that shown in FIG. 22, except that in

[0079] FIG. 18 The embodiment shown in FIG. 24 is similar to that shown in FIG. 23, except that in FIG. 5 The embodiment shown in FIG. 25 is similar to that shown in FIG. 24, except that in FIG. 18 The embodiment shown in FIG. 26 is similar to that shown in FIG. 25, except that in FIG. 5 The embodiment shown in FIG. 27 is similar to that shown in FIG. 26, except that in FIG. 19 The embodiment shown in FIG. 28 is similar to that shown in FIG. 27, except that in FIG. 5 The embodiment shown in FIG. 29 is similar to that shown in FIG. 28, except that in FIG. 19 The embodiment shown in FIG. 30 is similar to that shown in FIG. 29, except that in FIG. 5 The embodiment shown in FIG. 31 is similar to that shown in FIG. 30, except that in this case, the bottom surface of the overhanging structure defined by the conductive layer 106 includes a stepped surface. At this time, as those skilled in the art can understand, after the sacrificial layer 112 is deposited, a CMP process is used to form a planar surface of the sacrificial layer, and then the process of patterning the sacrificial layer is continued.

[0080] FIG. 20 The embodiment shown in FIG. 32 is similar to that shown in FIG. 31, except that in FIG. 19 The embodiment shown in FIG. 33 is similar to that shown in FIG. 32, except that in FIG. 20 The embodiment shown in FIG. 34 is similar to that shown in FIG. 33, except that inFIG. 19 In the embodiment shown in FIG. 6, the side surface of the conductive layer 106 is vertical or parallel to the thickness direction of the resonator.

[0081] FIG. 21 The embodiment shown in FIG. 7 is similar to that in FIG. 6, except that in the embodiment shown in FIG. 7, the inner side of the conductive layer 106 is a circular arc. FIG. 19 The embodiment shown in FIG. 8 is similar to that in FIG. 6, except that in the embodiment shown in FIG. 8, the inner side of the conductive layer 106 is a circular arc. FIG. 21 In the embodiment shown in FIG. 6, the side surface of the conductive layer 106 is vertical or parallel to the thickness direction of the resonator. FIG. 19 In the embodiment shown in FIG. 7, the side surface of the conductive layer 106 is vertical or parallel to the thickness direction of the resonator.

[0082] FIG. 22 The embodiment shown in FIG. 7 is similar to that in FIG. 6, except that in the embodiment shown in FIG. 7, the inner side of the conductive layer 106 is a circular arc. FIG. 19 The embodiment shown in FIG. 8 is similar to that in FIG. 6, except that in the embodiment shown in FIG. 8, the inner side of the conductive layer 106 is a circular arc. FIG. 22 In the embodiment shown in FIG. 7, the inner side of the conductive layer 106 is a circular arc. FIG. 19 In the embodiment shown in FIG. 8, the side surface of the conductive layer 106 is vertical or parallel to the thickness direction of the resonator.

[0083] FIG. 13 to FIG. 22 The side surface profile of the overhanging structure of the conductive layer 106 shown in FIG. 6 can be achieved by adjusting the etching scheme (for example, changing the gas ratio of dry etching and the etching time, etc.).

[0084] FIG. 23 The embodiment shown in FIG. 7 is similar to that in FIG. 6, except that in the embodiment shown in FIG. 7, the inner side of the conductive layer 106 is a circular arc. FIG. 3 The embodiment shown in FIG. 8 is similar to that in FIG. 6, except that in the embodiment shown in FIG. 8, the inner side of the conductive layer 106 is a circular arc. FIG. 23 In the embodiment shown in FIG. 7, the inner side of the conductive layer 106 is a circular arc. FIG. 3 In the embodiment shown in FIG. 8, the inner side of the conductive layer 106 is a circular arc.

[0085] FIG. 24 The embodiment shown in FIG. 7 is similar to that in FIG. 6, except that in the embodiment shown in FIG. 7, the inner side of the conductive layer 106 is a circular arc. FIG. 3 The embodiment shown in FIG. 8 is similar to that in FIG. 6, except that in the embodiment shown in FIG. 8, the inner side of the conductive layer 106 is a circular arc. FIG. 24 In the embodiment shown in FIG. 7, the inner side of the conductive layer 106 is a circular arc. FIG. 3 In the embodiment shown in FIG. 8, the inner side of the conductive layer 106 is a circular arc.

[0086] FIG. 25 The embodiment shown in FIG. 7 is similar to that in FIG. 6, except that in the embodiment shown in FIG. 7, the inner side of the conductive layer 106 is a circular arc. FIG. 3 The embodiment shown in FIG. 8 is similar to that in FIG. 6, except that in the embodiment shown in FIG. 8, the inner side of the conductive layer 106 is a circular arc. FIG. 25 In the embodiment shown in FIG. 7, the inner side of the conductive layer 106 is a circular arc. FIG. 3 In the embodiment shown in FIG. 8, the inner side of the conductive layer 106 is a circular arc.

[0087] FIG. 26The embodiment shown is similar to that shown in FIG. 5 except that in FIG. 26 the inner side of the dielectric layer 111 extends to the inner side of the outer side of the conductive layer 106 at the non-connection side of the top electrode, while in FIG. 5 the inner side of the dielectric layer 111 is flush with the inner side of the conductive layer 106, and the outer side of the dielectric layer 111 is flush with the outer side of the conductive layer 106 at the non-connection side of the top electrode.

[0088] FIG. 27 The embodiment shown is similar to that shown in FIG. 5 except that in FIG. 27 the inner side of the dielectric layer 111 extends to the inner side of the conductive layer 106, while in FIG. 5 the inner side of the dielectric layer 111 is flush with the inner side of the conductive layer 106.

[0089] FIG. 28 The embodiment shown is similar to that shown in FIG. 5 except that in FIG. 28 in the non-connection side of the top electrode, the dielectric layer 111 also extends to the outer side of the outer side of the conductive layer 106, while in FIG. 5 in the non-connection side of the top electrode, the outer side of the dielectric layer 111 is flush with the outer side of the conductive layer 106.

[0090] FIG. 23 to FIG. 28 The case where the edge of the dielectric layer 111 is not flush with the conductive layer 106 shown can be controlled by controlling the lateral etching rate of the conductive layer 106.

[0091] FIG. 29 The embodiment shown is similar to that shown in FIG. 3 except that in FIG. 29 in the connection side of the top electrode, the outer side edge of the overhang structure is on the lateral side of the acoustic mirror, and the lateral distance o between them can be in the range of 0.2 μm - 10 μm, while in FIG. 3 in the connection side of the top electrode, the outer side edge of the overhang structure is on the inner side of the acoustic mirror.

[0092] In the embodiment shown, the conductive part 106 can be partially disconnected at the non-connection side of the top electrode, and arranged in a non-annular shape. In an alternative embodiment, the sum of the lengths of the disconnected positions is not greater than 90% of the circumference of the effective area of the entire resonator. FIG. 30 The scheme shown can also be applied to the embodiments described above with reference to the drawings. FIG. 30

[0093] ​In the embodiment shown in the present application, the overhanging structure is arranged at the inner end of the conductive layer (i.e. inner end overhanging structure), but, as can be understood by those skilled in the art, the overhanging structure can also be arranged at the outer end of the conductive layer (i.e. outer end overhanging structure). The following will refer to the accompanying drawings to illustrate the fabrication process of the resonator shown in FIG. 31-37 An example of a bulk acoustic wave resonator with an outer end overhanging structure.

[0094] FIG. 31-33 For example, the bulk acoustic wave resonator shown in FIG. 1B is similar to the bulk acoustic wave resonator shown in

[0095] In FIG. 31 , at the non-connection side of the top electrode, the outer end of the conductive layer is provided with an overhanging structure, and the overhanging structure forms a gap with the surface of the top electrode.

[0096] In FIG. 32 , the conductive layer is provided with both an inner end overhanging structure and an outer end overhanging structure.

[0097] In FIG. 33 , unlike FIG. 32 , the resonator is further provided with a wing, a bridge structure and a protrusion.

[0098] The outer end overhanging structure of the conductive layer has a similar effect to the inner end overhanging structure described above, and when both the inner end and outer end overhanging structures are provided, the two cantilever beams will further form a resonance, thereby working together to improve the Q value of the resonator.

[0099] In addition, the sidewall of the outer end overhanging structure of the conductive layer can also have a similar profile to the sidewall of the inner end overhanging structure shown in FIG. 13 to FIG. 22 , and the relative position relationship between the dielectric layer 111 of the top layer of the outer end overhanging structure and the conductive layer 106 can also be similar to the case where the end surface is uneven as shown in FIG. 23 to FIG. 28

[0100] The following will refer to FIG. 34-37 to illustrate the fabrication process of the resonator shown in FIG. 33 .

[0101] First, the structure shown in FIG. 7 is formed, and then, similar to FIG. 8 , the sacrificial layer 112 is formed and patterned, and unlike FIG. 8 , there is also an outer sacrificial layer 112A arranged in the same layer as the sacrificial layer 112, which is located outside the sacrificial layer 112 and spaced apart from it. Next, similar to FIG. 10 ​, a conductive material layer and a conductive layer surface dielectric material layer are provided, thereby forming FIG. 34 as shown in the structure.

[0102] Secondly, similar to FIG. 11 , the conductive layer surface dielectric material layer is patterned to form a conductive layer surface dielectric layer 111, then the conductive material layer except that covered by the conductive layer surface dielectric layer 111 (which is the first etching stop layer at this time) is removed (for example, by etching) to form a conductive layer 106, in the process of removal, the conductive material layer above the sacrificial layer 112 is removed, and the conductive material layer above the outer sacrificial layer 112A outside the conductive layer is removed, in other words, in the process of removal, the etching process stops at the sacrificial layer 112 and the outer sacrificial layer 112A. Finally, a structure as shown in FIG. 35 is formed.

[0103] Thirdly, as shown in FIG. 36 , a photoresist 113 is provided as a second etching stop layer, which covers the conductive layer surface dielectric layer 111 and the exposed sacrificial layer 112, but does not cover the exposed outer sacrificial layer 112A.

[0104] Then, etching is performed to remove the outer sacrificial layer 112A outside the conductive layer 106, and to remove the top electrode material layer outside the conductive layer 106 to form the top electrode 105, thereby forming a structure as shown in FIG. 37 .

[0105] Finally, the sacrificial layer 112, the outer sacrificial layer 112A, and the sacrificial layer 110 for forming the wing and bridge structure are released, to form a resonator structure as shown in FIG. 33 .

[0106] 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 the numerical range, in addition to the end point value, which is within the protection scope of the present application.

[0107] In the present application, up and down are relative to the bottom surface of the substrate of the resonator, for a component, the side close to the bottom surface is the lower side, and the side away from the bottom surface is the upper side.

[0108] In the present application, inner and outer are relative to the center of the effective area of the resonator in the lateral direction or the radial direction, the side or the end of a component close to the center is the inner side or the inner end, and the side or the end of the component away from the center 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 in the lateral direction or the radial direction, and the outer side of the position means further away from the center than the position in the lateral direction or the radial direction.

[0109] As can be understood by those skilled in the art, the bulk acoustic wave resonator according to the present application can be used to form a filter or an electronic device.

[0110] The electronic device herein includes, but is not limited to, intermediate products such as radio frequency front ends, filter amplification modules, and terminal products such as mobile phones, WIFI, and unmanned aerial vehicles.

[0111] Based on the above, the present application proposes the following technical solutions:

[0112] 1. A bulk acoustic wave resonator, comprising:

[0113] a substrate;

[0114] an acoustic mirror;

[0115] a bottom electrode;

[0116] a top electrode; and

[0117] a piezoelectric layer,

[0118] wherein:

[0119] an overlapping area of the acoustic mirror, the bottom electrode, the piezoelectric layer and the top electrode in a thickness direction of the resonator constitutes an effective area of the resonator;

[0120] an edge of the top electrode surrounding the effective area is further provided with a conductive layer, and the conductive layer is electrically connected with the top electrode;

[0121] at least a part of a bottom surface of an inner end and / or an outer end of the conductive layer has a gap with an upper surface of the top electrode to form a suspended structure.

[0122] 2. The resonator according to 1, wherein:

[0123] the suspended structure is arranged at a connecting edge of the top electrode and / or a non-connecting edge of the top electrode.

[0124] 3. The resonator according to 2, wherein:

[0125] the suspended structure is a ring-shaped suspended structure; or

[0126] the suspended structure is arranged at the connecting edge of the top electrode and part of the non-connecting edge of the top electrode.

[0127] 4. The resonator according to 3, wherein:

[0128] the suspended structure is discontinuously arranged circumferentially on the non-connecting edge of the top electrode, and a sum of lengths of the discontinuous positions is not greater than 90% of a circumference of the effective area of the entire resonator.

[0129] 5. The resonator according to claim 1, wherein:

[0130] The width of the overhang structure is in the range of 0.2 μm to 20 μm.

[0131] 6. The resonator according to any one of claims 1 to 5, wherein:

[0132] The non-connected side of the top electrode is provided with the overhang structure, and the width of the contact portion of the non-connected side with the conductive layer is in the range of 0.2 μm to 10 μm.

[0133] 7. The resonator according to any one of claims 1 to 6, wherein: the connected side of the top electrode is provided with an inner end overhang structure formed at the inner end of the conductive layer, and the lateral distance between the outer side edge of the gap of the inner end overhang structure and the edge of the acoustic mirror is in the range of 0.2 μm to 10 μm.

[0134] 8. The resonator according to claim 7, wherein:

[0135] The outer side edge of the gap of the inner end overhang structure is inside the acoustic mirror edge in the lateral direction of the resonator; or

[0136] The outer side edge of the gap of the inner end overhang structure is outside the acoustic mirror edge in the lateral direction of the resonator.

[0137] 9. The resonator according to any one of claims 1 to 7, wherein:

[0138] The top electrode is provided with a bridge structure at the connected side of the top electrode, and / or the top electrode is provided with a wing structure at the non-connected side of the top electrode;

[0139] The inner side edge of the bridge structure and / or wing structure is inside the effective area; and / or

[0140] The top electrode further comprises a protrusion structure provided at least around the inner side edge of the bridge structure and / or wing structure.

[0141] 10. The resonator according to claim 9, wherein:

[0142] The top electrode is provided with an inner end overhang structure formed at the inner end of the conductive layer; and

[0143] The inner side edge of the wing structure and / or bridge structure is inside or flush with the outer side edge of the gap of the inner end overhang structure in the lateral direction.

[0144] 11. The resonator according to claim 10, wherein:

[0145] The distance between the inner side edge of the wing or bridge structure and the outer side edge of the gap of the inner end overhang structure in the lateral direction is in the range of 0.2 μm to 10 μm.

[0146] 12. The resonator according to any one of 1 to 11, wherein:

[0147] The side surface of the inner end and / or outer end overhang structure of the conductive layer is parallel to the thickness direction of the resonator or is at an angle to the thickness direction, or the side surface of the inner end and / or outer end overhang structure of the conductive layer includes an arc surface.

[0148] 13. The resonator according to 1, wherein:

[0149] The upper surface of the top electrode and / or the upper surface of the conductive layer is provided with a non-conductive medium layer.

[0150] 14. The resonator according to 13, wherein:

[0151] The inner end of the non-conductive medium layer of the conductive layer extends to the inner side of the conductive layer at the connecting side and / or non-connecting side of the top electrode; and / or

[0152] The outer end of the non-conductive medium layer of the conductive layer extends to the outer side of the conductive layer at the non-connecting side of the top electrode.

[0153] 15. The resonator according to 13, wherein:

[0154] The connecting side of the top electrode is provided with an inner end overhang structure formed at the inner end of the conductive layer; and

[0155] The inner end of the non-conductive medium layer of the top electrode is inside the outer side edge of the gap of the inner end overhang structure in the lateral direction.

[0156] 16. The resonator according to 1, wherein:

[0157] The bottom surface of the conductive layer defining the overhang structure includes a stepped surface and / or a horizontal surface.

[0158] 17. A filter comprising the resonator according to any one of 1 to 16.

[0159] 18. An electronic device comprising the filter according to 17 or the resonator according to any one of 1 to 16.

[0160] 19. A method of manufacturing a bulk acoustic wave resonator, wherein:

[0161] The method includes the step of forming a stack structure of a bottom electrode, a piezoelectric layer, and a top electrode material layer on a substrate;

[0162] The method further includes:

[0163] Step 1: forming and patterning a sacrificial layer on the stacked structure;

[0164] Step 2: forming a conductive material layer covering the patterned sacrificial layer and a top electrode material layer, the conductive material layer being electrically connected with the top electrode material layer;

[0165] Step 3: disposing and patterning a barrier layer on the conductive material layer, inner ends of the patterned barrier layer being inside corresponding outer ends of the sacrificial layer in a transverse direction of the resonator;

[0166] Step 4: removing the conductive material layer and the top electrode material layer outside the conductive material layer covered by the patterned barrier layer to form a conductive layer and a top electrode;

[0167] Step 5: releasing the sacrificial layer to form a gap between a bottom surface of an inner end of the conductive layer and an upper surface of the top electrode to form an inner end overhang structure,

[0168] wherein:

[0169] the resonator comprises an acoustic mirror, an effective area of the resonator is formed by an overlapping area of the acoustic mirror, the top electrode, the piezoelectric layer and the bottom electrode in a thickness direction of the resonator, and in Step 4, the conductive layer is disposed around an edge of the effective area.

[0170] 20. The method of 19, wherein:

[0171] in Step 3, the barrier layer is a non-conductive medium layer of the conductive layer.

[0172] 21. The method of 19, wherein:

[0173] an upper surface of the top electrode material layer is provided with the non-conductive medium layer of the top electrode;

[0174] between Step 1 and Step 2, further comprising Step 1A: removing the non-conductive medium layer of the top electrode not covered by the patterned sacrificial layer with the patterned sacrificial layer as a barrier layer.

[0175] 22. The method of 19, wherein:

[0176] the top electrode is provided with a bridge structure at a connecting edge of the top electrode, and / or the top electrode is provided with a wing structure at a non-connecting edge of the top electrode; and

[0177] in Step 1, in the transverse direction of the resonator, an inner side edge of the bridge structure and / or the wing structure is inside or flush with an outer end of the patterned sacrificial layer.

[0178] 23. The method of claim 19, wherein:

[0179] In step 1, the patterned sacrificial layer includes a first sacrificial layer portion and a second sacrificial layer portion, the second sacrificial layer portion being spaced apart from the first sacrificial layer portion in a lateral direction and outside the first sacrificial layer portion, the first sacrificial layer portion being used to form the inner end overhang structure;

[0180] In step 3, the barrier layer is a first barrier layer;

[0181] The step 4 includes:

[0182] Step 41: removing the conductive material layer except for the portion of the conductive material layer covered by the patterned first barrier layer to form the conductive layer, in step 41, the conductive material layer above the first sacrificial layer portion is removed, and the conductive material layer above the second sacrificial layer portion outside the conductive layer is removed;

[0183] Step 42: providing a second barrier layer, the second barrier layer covering the patterned first barrier layer and the portion of the first sacrificial layer portion exposed due to the removal of the conductive material layer;

[0184] Step 43: removing the second sacrificial layer portion outside the conductive layer and the top electrode material layer to form the top electrode;

[0185] The step 5 includes: releasing the first sacrificial layer portion to form the inner end overhang structure, and releasing the remaining second sacrificial layer portion to form an outer end overhang structure.

[0186] While the embodiments of the application have been illustrated and described, it will be understood by those skilled in the art that various changes can be made and equivalents can be substituted for elements thereof without departing from the principles and spirit of the application. In addition, many modifications can be made to adapt to a particular situation and the scope of the application should be governed by the claims and their equivalents.

Claims

1. A bulk acoustic wave resonator, comprising: substrate; Acoustic mirror; bottom electrode; Top electrode; and Piezoelectric layer, in: The overlapping area of ​​the acoustic mirror, the bottom electrode, the piezoelectric layer and the top electrode in the thickness direction of the resonator constitutes the effective area of ​​the resonator; A conductive layer is further provided on the edge of the active area surrounding the upper side of the top electrode, and the conductive layer is electrically connected to the top electrode; There is a gap between at least a portion of the bottom surface of the inner end and / or the outer end of the conductive layer and the upper surface of the top electrode to form a suspended structure, so that the conductive layer forms a cantilever beam structure.

2. The resonator according to claim 1, wherein: The suspended structure is provided at the connection side of the top electrode and / or the non-connection side of the top electrode.

3. The resonator according to claim 2, wherein: The suspended structure is a ring-shaped suspended structure; or The suspended structure is arranged on the connection edge of the top electrode and part of the non-connection edge of the top electrode.

4. The resonator according to claim 3, wherein: The suspended structure is discontinuously arranged in the circumferential direction of the non-connected edge of the top electrode, and the sum of the lengths of the disconnected positions is no more than 90% of the circumference of the effective area of ​​the entire resonator.

5. The resonator according to claim 1, wherein: The width of the suspended structure is in the range of 0.2 μm to 20 μm.

6. The resonator according to any one of claims 1 to 5, wherein: The non-connected side of the top electrode is provided with the suspended structure, and the width of the contact portion between the conductive layer and the non-connected side is in the range of 0.2 μm-10 μm.

7. The resonator according to any one of claims 1 to 5, wherein: The connecting edge of the top electrode is provided with an inner end suspended structure formed at the inner end of the conductive layer, and the lateral distance between the outer edge of the gap of the inner end suspended structure and the edge of the acoustic mirror is in the range of 0.2μm-10μm.

8. The resonator according to claim 7, wherein: The outer edge of the gap of the inner end suspended structure is located on the inner side of the edge of the acoustic mirror in the lateral direction of the resonator; or The outer edge of the gap of the inner end suspended structure is located outside the edge of the acoustic mirror in the lateral direction of the resonator.

9. The resonator according to any one of claims 1 to 5, wherein: The top electrode is provided with a bridge structure at a connection side of the top electrode, and / or the top electrode is provided with a cantilever at a non-connection side of the top electrode; The inner edges of the bridge structure and / or cantilever structure are located inside the effective area; and / or The top electrode further includes a protruding structure at least arranged around the inner edge of the bridge structure and / or the cantilever structure.

10. The resonator of claim 9, wherein: The top electrode is provided with an inner end suspended structure formed at the inner end of the conductive layer; and The inner edges of the wing and / or bridge structure are located inside or flush with the outer edges of the gap of the inner end suspended structure in the transverse direction.

11. The resonator of claim 10, wherein: A distance in a lateral direction between an inner edge of the wing or bridge structure and an outer edge of the gap of the inner-end suspended structure is in a range of 0.2 μm to 10 μm.

12. The resonator according to any one of claims 1 to 5, wherein: The side surfaces of the inner and / or outer suspended structures of the conductive layer are parallel to the thickness direction of the resonator or form an angle with the thickness direction, or the side surfaces of the inner and / or outer suspended structures of the conductive layer include arc surfaces.

13. The resonator of claim 1 , wherein: A non-conductive dielectric layer is provided on the upper surface of the top electrode and / or the upper surface of the conductive layer.

14. The resonator of claim 13, wherein: At the connection side and / or non-connection side of the top electrode, the inner end of the non-conductive dielectric layer of the conductive layer extends to the inner side of the conductive layer; and / or At the non-connected side of the top electrode, an outer end of the non-conductive dielectric layer of the conductive layer extends to the outside of the conductive layer.

15. The resonator of claim 13, wherein: The connecting edge of the top electrode is provided with an inner end suspended structure formed at the inner end of the conductive layer; and The inner end of the non-conductive dielectric layer of the top electrode is located inside the outer edge of the gap of the inner end suspended structure in the lateral direction.

16. The resonator of claim 1 , wherein: The bottom surface of the conductive layer defining the suspended structure includes a stepped surface and / or a horizontal surface.

17. A filter comprising the resonator according to any one of claims 1 to 16.

18. An electronic device comprising the filter according to claim 17 or the resonator according to any one of claims 1 to 16.

19. A method for manufacturing a bulk acoustic wave resonator, wherein: The method comprises the steps of: forming a stacked structure of a bottom electrode, a piezoelectric layer and a top electrode material layer on a substrate; The method further comprises: Step 1: forming and patterning a sacrificial layer on the stacked structure; Step 2: forming a conductive material layer covering the patterned sacrificial layer and the top electrode material layer, wherein the conductive material layer is electrically connected to the top electrode material layer; Step 3: Disposing and patterning a barrier layer on the conductive material layer, wherein an inner end of the patterned barrier layer is located inward of a corresponding outer end of the sacrificial layer in a lateral direction of the resonator; Step 4: removing the conductive material layer and the top electrode material layer outside the conductive material layer covered by the patterned barrier layer to form a conductive layer and a top electrode; Step 5: releasing the sacrificial layer to form a gap between the bottom surface of the inner end of the conductive layer and the upper surface of the top electrode to form an inner end suspended structure, so that the conductive layer forms a cantilever beam structure. in: The resonator includes an acoustic mirror, and the overlapping area of ​​the acoustic mirror, top electrode, piezoelectric layer, and bottom electrode of the resonator in the thickness direction of the resonator forms an effective area of ​​the resonator. In step 4, the conductive layer is arranged around the edge of the effective area.

20. The method of claim 19, wherein: In step 3, the barrier layer is a non-conductive dielectric layer of the conductive layer.

21. The method of claim 19, wherein: A non-conductive dielectric layer of a top electrode is provided on the upper surface of the top electrode material layer; Between step 1 and step 2, step 1A is further included: using the patterned sacrificial layer as a barrier layer, removing the non-conductive dielectric layer of the top electrode not covered by the patterned sacrificial layer.

22. The method of claim 19, wherein: The top electrode is provided with a bridge structure at a connection side of the top electrode, and / or the top electrode is provided with a cantilever at a non-connection side of the top electrode; and In step 1, in the lateral direction of the resonator, the inner edges of the bridge structure and / or the cantilever are located inside or flush with the outer ends of the patterned sacrificial layer.

23. The method of claim 19, wherein: In step 1, the patterned sacrificial layer includes a first sacrificial layer portion and a second sacrificial layer portion, the second sacrificial layer portion is spaced apart from the first sacrificial layer portion in a lateral direction and is located outside the first sacrificial layer portion, and the first sacrificial layer portion is used to form the inner end suspended structure; In step 3, the barrier layer is a first barrier layer; The step 4 comprises: Step 41: removing the conductive material layer outside the portion covered by the patterned first barrier layer to form a conductive layer. In step 41, the conductive material layer above the first sacrificial layer portion is removed, and the conductive material layer above the second sacrificial layer portion outside the conductive layer is removed. Step 42: providing a second barrier layer, wherein the second barrier layer covers the patterned first barrier layer and a portion of the first sacrificial layer portion exposed due to the removal of the conductive material layer; Step 43: removing the second sacrificial layer portion and the top electrode material layer outside the conductive layer to form the top electrode; The step 5 includes: releasing the first sacrificial layer portion to form the inner-end suspended structure, and releasing the remaining second sacrificial layer portion to form the outer-end suspended structure.

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