Manufacturing method of thin-film bulk acoustic resonator and filter

Abstract

The present invention relates to a method for manufacturing a thin film bulk acoustic wave resonator and a filter, comprising: forming a first substrate having a first sacrificial layer; forming a first electrode, a piezoelectric layer and a second electrode in sequence, wherein the first electrode covers the first sacrificial layer; forming an annular groove penetrating the corresponding electrode on at least one of the first electrode and the second electrode; forming an electrode lead-out structure having an arched bridge structure on the corresponding electrode having the annular groove, wherein the arched bridge structure is opposite to the annular groove; removing the first sacrificial layer to form a first cavity. The present invention defines the boundary of the effective resonance region by the region where the annular gap of the electrode lead-out structure is located, and makes the end of the corresponding electrode at the boundary of the effective resonance region contact with the gas in the gap through the annular groove, thereby achieving the effect of eliminating the boundary noise of the electrode in the effective resonance region, thereby improving the Q value of the resonator.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor device manufacturing, and in particular to a method for manufacturing a thin film bulk acoustic wave resonator and a filter. Background Art

[0002] Since analog RF communication technology was developed in the early 1990s, RF front-end modules have gradually become the core components of communication equipment. Among all RF front-end modules, filters have become the components with the strongest growth momentum and the greatest development prospects. With the rapid development of wireless communication technology and the increasing maturity of 5G communication protocols, the market has also put forward more stringent standards for the performance of RF filters in all aspects. The performance of the filter is determined by the resonator units that make up the filter. Among the existing filters, the film bulk acoustic resonator (FBAR) has become one of the most suitable filters for 5G applications due to its small size, low insertion loss, large out-of-band suppression, high quality factor, high operating frequency, large power capacity and good anti-static shock ability.

[0003] Generally, a film bulk acoustic wave resonator includes two film electrodes, and a piezoelectric film layer is arranged between the two film electrodes. Its working principle is to utilize the piezoelectric film layer to generate vibration under an alternating electric field. The vibration excites a bulk acoustic wave that propagates along the thickness direction of the piezoelectric film layer. The sound wave is reflected back when it reaches the interface between the upper and lower electrodes and the air, and then reflects back and forth inside the film to form an oscillation. When the sound wave propagates in the piezoelectric film layer at an odd multiple of half the wavelength, a standing wave oscillation is formed.

[0004] However, the quality factor (Q) of the currently manufactured cavity-type FBAW resonators cannot be further improved, and therefore cannot meet the requirements of high-performance radio frequency systems. Summary of the invention

[0005] The object of the present invention is to provide a method for manufacturing a thin film bulk acoustic wave resonator and a filter, which can improve the quality factor of the thin film bulk acoustic wave resonator and thus improve the device performance.

[0006] In order to achieve the above object, the present invention provides a method for manufacturing a thin film bulk acoustic wave resonator, characterized by comprising:

[0007] forming a first substrate having a first sacrificial layer;

[0008] forming a first electrode, a piezoelectric layer and a second electrode in sequence on the first substrate, wherein the first electrode covers the first sacrificial layer;

[0009] An annular groove penetrating the corresponding electrode is formed on at least one of the first electrode and the second electrode; an electrode lead-out structure having an arched bridge structure is formed on the corresponding electrode having the annular groove, the arched bridge structure being opposite to the annular groove;

[0010] The first sacrificial layer is removed to form a first cavity.

[0011] The present invention also provides a filter, comprising at least one thin film bulk acoustic wave resonator formed by the method for manufacturing the thin film bulk acoustic wave resonator as described above.

[0012] The beneficial effects of the method for manufacturing a thin film bulk acoustic wave resonator of the present invention are:

[0013] An annular groove is formed by etching on the first electrode and / or the second electrode to disconnect the corresponding electrode, and then an electrode lead-out structure with an arch bridge structure is formed on the corresponding electrode to electrically connect the disconnected electrode parts; the annular groove formed on the corresponding electrode exposes the boundary of the corresponding electrode to the annular gap formed by the arch bridge, thereby achieving the effect of eliminating the electrode boundary noise in the effective resonance area, thereby improving the Q value of the resonator; the first cavity is formed by etching the supporting layer, which can simplify the formation process and reduce the manufacturing cost.

[0014] Furthermore, when an electrode lead-out structure is formed on the first electrode, the process steps can be simplified by directly forming the electrode lead-out structure on the first substrate and then forming the first electrode on the electrode lead-out structure. In addition, a first sacrificial layer is filled in the first cavity so that the subsequently formed first electrode remains flat, thereby facilitating the formation of a piezoelectric layer on the flat first electrode, so that the upper and lower surfaces of the piezoelectric layer are both planes, ensuring that the piezoelectric layer has a good lattice orientation, improving the piezoelectric properties of the piezoelectric layer, and thereby improving the performance of the resonator.

[0015] Furthermore, when an electrode lead-out structure is formed on the second electrode, an electrode lead-out structure having an arched bridge structure is formed by forming an annular sacrificial protrusion, and an annular gap is formed after removing the annular sacrificial protrusion, which not only simplifies the formation process of the electrode lead-out structure, but also separates the electrodes inside and outside the annular groove, and electrically connects the disconnected electrodes through the electrode lead-out structure, thereby reducing the impedance of the electrode.

[0016] Furthermore, the impedance of the electrode lead-out structure is lower than the impedance of the corresponding electrode, so as to reduce the electrode impedance, make the electrode lead-out structure have better conductivity, and improve the conductivity.

[0017] Furthermore, the projections of the first electrode and the second electrode in the outer region of the arch bridge on the plane where the piezoelectric layer is located are at least partially staggered, which can avoid the high-frequency coupling problem caused by potential floating, prevent the formation of parasitic capacitance, and help improve the resonator quality factor. Similarly, when the first electrode and the second electrode are both provided with electrode lead structures, the projections of the two on the plane where the piezoelectric layer is located are at least partially staggered, which can also avoid the high-frequency coupling problem.

[0018] Furthermore, the first electrode and the second electrode extend from the effective resonance region to the first substrate outside the first cavity, which can improve the structural strength of the resonator. In addition, the electrode lead-out structure formed on the corresponding electrode also extends from the effective resonance region to the first substrate outside the first cavity, so as to improve the structural strength of the resonator.

[0019] Furthermore, the piezoelectric layer is a complete film layer, which can ensure the structural strength of the resonator and improve the yield rate of the resonator.

[0020] Furthermore, a first groove is provided in the piezoelectric layer so that the edge of the piezoelectric layer is exposed to the gas, which can suppress the shear wave loss of the piezoelectric layer. When the first groove is entirely located within the annular gap, the Q value of the resonator can be better improved.

[0021] The filter of the present invention has the following beneficial effects:

[0022] The filter is formed by connecting the thin film bulk acoustic wave resonators to ensure that the filter has good structural stability, and because the electrode impedance of the resonator is low, the conductivity of the filter can be improved and the accuracy of filtering can be improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0024] Figure 1 is a flow chart of a method for manufacturing a thin film bulk acoustic wave resonator according to embodiment 1 of the present invention;

[0025] Figures 2 to 6 A schematic structural diagram corresponding to different steps of a method for manufacturing a thin film bulk acoustic wave resonator according to Embodiment 1 of the present invention is shown;

[0026] Figure 7 A schematic structural diagram corresponding to different steps of another method for manufacturing a thin film bulk acoustic wave resonator formed in Embodiment 2 of the present invention is shown;

[0027] Figure 8 FIG. 3 is a schematic diagram of the structure of a thin film bulk acoustic wave resonator manufactured by the method for manufacturing a thin film bulk acoustic wave resonator according to Example 3 of the present invention;

[0028] Fig. 9 FIG. 4 is a schematic diagram of the structure of a thin film bulk acoustic wave resonator manufactured by the method for manufacturing a thin film bulk acoustic wave resonator according to Example 4 of the present invention.

[0029] Description of reference numerals:

[0030] 1. First substrate; 11. Base; 12. Support layer; 121. First cavity; 121', First sacrificial layer; 13. First groove; 1414. Second groove; 21. First electrode; 22. Piezoelectric layer; 23. Second electrode; 24. Annular groove; 25. First groove; 3. First electrode lead-out structure; 31. First arch bridge; 32. First annular gap; 32', First annular sacrificial protrusion; 4. Second electrode lead-out structure; 41. Second arch bridge; 42. Second annular gap; 42', Second annular sacrificial protrusion; 5. Carrying substrate; 6. Second substrate; 61. Second sacrificial layer; 7. Temporary substrate. DETAILED DESCRIPTION

[0031] The following is a further detailed description of the thin film bulk acoustic resonator and the method for making the same in combination with the accompanying drawings and specific embodiments. The advantages and features of the present invention will become clearer according to the following description and drawings. However, it should be noted that the concept of the technical solution of the present invention can be implemented in a variety of different forms and is not limited to the specific embodiments described herein. The drawings are all in a very simplified form and are not in precise proportions, and are only used to conveniently and clearly assist in explaining the purpose of the embodiments of the present invention.

[0032] The terms "first", "second", etc. in the specification and claims are used to distinguish between similar elements and are not necessarily used to describe a specific order or time sequence. It is to be understood that, where appropriate, these terms used in this way are interchangeable, for example, so that the embodiments of the invention described herein can be operated in an order other than that described or shown herein. Similarly, if the method described herein includes a series of steps, the order of these steps presented herein is not necessarily the only order in which these steps can be performed, and some of the steps described may be omitted and / or some other steps not described herein may be added to the method. If the components in a certain figure are the same as the components in other figures, although these components can be easily identified in all figures, in order to make the description of the figures clearer, this specification will not mark all the same component numbers in each figure.

[0033] Example 1

[0034] Figure 1 FIG. 1 is a flow chart of a method for manufacturing a thin film bulk acoustic wave resonator according to Embodiment 1 of the present invention, referring to Figure 1 Embodiment 1 provides a method for manufacturing a thin film bulk acoustic wave resonator, and the method for manufacturing a thin film bulk acoustic wave resonator includes:

[0035] S01: forming a first substrate having a first sacrificial layer;

[0036] S02: forming a first electrode, a piezoelectric layer and a second electrode in sequence on the first substrate, wherein the first electrode covers the first sacrificial layer;

[0037] S03: forming an annular groove penetrating the corresponding electrode on at least one of the first electrode and the second electrode; forming an electrode lead-out structure having an arched bridge structure on the corresponding electrode having the annular groove, wherein the arched bridge structure is opposite to the annular groove;

[0038] S04: removing the first sacrificial layer to form a first cavity.

[0039] Steps S0N do not represent a sequential order.

[0040] In this embodiment, the first electrode 21 and the second electrode 24 both form an electrode lead-out structure. The electrode lead-out structure formed on the first electrode 21 is referred to as the first electrode lead-out structure 3 , and the electrode lead-out structure formed on the second electrode 23 is referred to as the second electrode lead-out structure. Figures 2 to 7 FIG. 1 is a schematic diagram of the structure corresponding to the corresponding steps of the method for manufacturing a thin film bulk acoustic wave resonator of this embodiment, with reference to FIG. Figures 2 to 7 The method for manufacturing the thin film bulk acoustic wave resonator provided in this embodiment is described in detail.

[0041] refer to Figure 2 , forming a first substrate 1 having a first sacrificial layer 121'. In this embodiment, the first substrate 1 includes a supporting layer 12 and a base 11, and the method for forming the first substrate 1 having the first sacrificial layer 121' includes: providing a base 11; forming a supporting layer 12 on the base 11; patterning the supporting layer 12 to form a first cavity; filling the first cavity to form a first sacrificial layer 121', wherein the first surface of the first sacrificial layer 121' is flush with the first surface of the supporting layer 12. It should be noted that the first surface of the supporting layer 12 is the surface of the supporting layer 12 adjacent to the first electrode 21, and the first surface of the first sacrificial layer 121' is also the surface adjacent to the first electrode 21. The first sacrificial layer 121' can be formed by deposition. To ensure that the first surface of the first sacrificial layer 121' is flush with the first surface of the supporting layer 12, the first sacrificial layer 121' formed by deposition needs to be flattened. The flattening process can use a chemical mechanical polishing process to ensure that the first electrode, the piezoelectric layer and the second electrode formed subsequently are formed on a flat layer, so that the first electrode, the piezoelectric layer and the second electrode remain flat. The material of the first sacrificial layer 121 ′ includes phosphosilicate glass, low temperature silicon dioxide, borophosphosilicate glass, germanium, amorphous carbon, polyimide or photoresist.

[0042] The support layer 12 can be bonded to the substrate 11 by means of a bonding layer. The material of the bonding layer includes silicon oxide, silicon nitride, silicon oxynitride, silicon carbonitride or ethyl silicate. In addition, the bonding layer can also use a binder such as a photocurable material or a thermosetting material, such as a die attach film (DAF) or a dry film (Dry Film). In addition, the support layer 12 can also be formed on the substrate 11 by deposition, and the deposition process includes chemical vapor deposition and physical vapor deposition. The material of the substrate 11 can be at least one of the following materials: silicon (Si), germanium (Ge), silicon germanium (SiGe), carbon silicon (SiC), carbon germanium silicon (SiGeC), indium arsenide (InAs), gallium arsenide (GaAs), indium phosphide (InP) or other III / V compound semiconductors. The material of the support layer 12 includes a dielectric material, such as silicon dioxide, silicon nitride, aluminum oxide, aluminum nitride, silicon oxynitride or silicon carbonitride.

[0043] The first cavity can be formed on the support layer 12 by etching, and the first cavity penetrates part of the support layer 12, that is, the first cavity extends to part of the thickness of the support layer 12. In other embodiments, the first cavity completely penetrates the support layer 12. In this embodiment, the cross-sectional shape of the first cavity can be a rectangle, but in other embodiments of the present invention, the cross-sectional shape of the first cavity can also be a circle, an ellipse, or a polygon other than a rectangle, such as a pentagon, a hexagon, etc. The shape of the first sacrificial layer 121' is the same as the shape of the first cavity.

[0044] In another embodiment, the first substrate 1 includes a semiconductor substrate, and a method for forming the first substrate 1 having a first sacrificial layer 121' includes: providing the first substrate 1; etching the first substrate 1 to form a first cavity, wherein the first cavity extends to a partial thickness of the first substrate 1; filling the first cavity to form a first sacrificial layer 121', wherein a first surface of the first sacrificial layer 121' is flush with a first surface of the first substrate 1.

[0045] Reference Figure 3-Figure 4 Before forming the first electrode, a first electrode lead-out structure 3 having a first arch bridge 31 structure is formed on the first sacrificial layer 121', and the first electrode lead-out structure 3 extends to the first substrate 1 outside the first sacrificial layer 121'. Specifically:

[0046] refer to Figure 3, a first groove 13 is formed on the first sacrificial layer 121', and the first groove 13 is located around the effective resonance area; a second groove 14 is formed in the first groove 13, and the depth of the second groove 14 is greater than the depth of the first groove 13, and the second groove 14 is located at the edge of the effective resonance area. It should be noted that the second groove 14 forms a closed ring, so that the first arch bridge 31 structure formed subsequently and the first annular sacrificial protrusion 32' therein form a closed ring, so that the first annular gap 32 formed after removing the first annular sacrificial protrusion 32' forms a closed ring, and the area surrounded by the first annular sacrificial gap is the effective resonance area, and the effective resonance area is surrounded by the part of the first sacrificial layer 121' located inside and outside the effective resonance area, and the edge of the effective resonance area is defined by the boundary of the second annular sacrificial protrusion.

[0047] In order to facilitate the electrical connection between the first electrode lead-out structure 3 formed in the first groove 13 and the outside, the first electrode lead-out structure 3 needs to have a second portion extending outside the effective resonance region to serve as an electrode connection end. Therefore, the first groove 13 can extend from the periphery of the effective resonance region to the first substrate 1 on the periphery of the first sacrificial layer 121', so that the first electrode lead-out structure 3 formed subsequently extends from the periphery of the effective resonance region to the first substrate 1 on the periphery of the first sacrificial layer 121'; or, the first groove 13 can extend from part of the periphery of the effective resonance region to the first substrate 1 on the periphery of the first sacrificial layer 121'. It should be noted that the first groove 13 can be formed on the first sacrificial layer 121' and the first substrate 1 by an etching process. The material of the first annular sacrificial protrusion 32' can refer to the material of the first sacrificial layer 121' mentioned above.

[0048] Since when the first groove 13 extends from part of the effective resonance zone to the first substrate 1 outside the first sacrificial layer 121', the first electrode lead-out structure 3 formed subsequently extends partly from the annular sacrificial protrusion to the first substrate 1 outside the first sacrificial layer 121', in order to keep the surfaces of the first electrode lead-out structure 3 and the first substrate 1 flush, a dielectric layer is also formed on the first substrate 1, the dielectric layer is continuously connected to the first electrode lead-out structure 3 or has a gap, and the dielectric layer is flush with the surface of the first electrode lead-out structure facing the first electrode, thereby facilitating the formation of the electrode on a flat surface.

[0049] refer to Figure 4, a first electrode lead-out structure 3 is formed in the first groove 13, and the first electrode lead-out structure 3 fills the first groove 13 outside the second groove 14; a first annular sacrificial protrusion 32' is formed on the first electrode lead-out structure 3 located in the second groove 14; the first annular sacrificial protrusion 32' is removed to form a first annular gap. It should be noted that the first electrode lead-out structure 3 can be formed in the first groove 13 and the second groove 14 by deposition, and the part formed in the second groove 14 forms a first arch bridge 31 structure. The deposition method includes physical vapor deposition or chemical vapor deposition. In order to form the electrode formed subsequently on a flat surface, the first annular sacrificial protrusion 32', the first sacrificial layer 121' and the first substrate 1 can be flattened so that the surfaces of the three are kept flush. In this embodiment, the first annular sacrificial protrusion 32' can be removed together with the first sacrificial layer 121' later, and the specific steps are as follows. In other embodiments, the first annular sacrificial protrusion 32 ′ may also be removed before forming the first electrode 21 . However, in order to facilitate the subsequent formation of the first electrode 21 to remain flat, it is necessary to fill it with sacrificial material and make its upper surface flush with the upper surface of the first electrode 21 .

[0050] The first electrode lead-out structure 3 also includes a lap portion connected to the first arch bridge structure 31 and extending to the periphery of the first sacrificial layer 121', and the lap portion surrounds part of the periphery or the entire periphery of the first electrode 21. Specifically, the lap portion may partially extend to the outer edge of the first substrate 1 outside the first sacrificial layer 121', or may fully extend to the outer edge of the first substrate 1 outside the first sacrificial layer 121' to be electrically connected to the outside. When the lap portion fully extends to the outer edge of the first substrate 1 outside the first sacrificial layer 121', the structural strength of the resonator is better. In addition, the first electrode lead-out structure 3 may be distributed on the first electrode 21 without being etched, that is, the lap portion may be a planar structure laid on the first electrode 21; or, the first electrode lead-out structure 3 may be etched to form a plurality of lap portions of strip-shaped structures, and the plurality of strip-shaped lap portions may be symmetrically distributed on the first electrode 21 to improve the structural strength of the resonator. Since the first electrode lead-out structure 3 only needs to connect the first electrode 21 disconnected by the annular groove 24 and extend to the first substrate 1 outside the first sacrificial layer 121', its specific structure is not further limited in the present application. In this embodiment, the impedance of the first electrode lead-out structure 3 is lower than the impedance of the first electrode, so that the first electrode with an annular groove formed later is connected through the first electrode lead-out structure 3, and the first electrode disconnected by the annular groove is connected, thereby reducing the impedance of the first electrode. The material of the first electrode lead-out structure 3 is a metal material, and the metal material includes one or more of gold, silver, tungsten, platinum, aluminum, copper, titanium, tin, and nickel.

[0051] Continue to refer to Figure 4, a first electrode 21, a piezoelectric layer 22, and a second electrode 23 are sequentially formed on the first substrate 1, and the first electrode 21 covers the first sacrificial layer 121'. The first electrode 21 and the second electrode 23 can be formed by a physical vapor deposition process and an etching process, and the first electrode 21 and the second electrode 23 extend around the first substrate 1 outside the first sacrificial layer 121' to improve the structural strength of the resonator. In other embodiments, when forming the first electrode 21 and the second electrode 23, the corresponding electrodes are etched so that part of the first electrode 21 and part of the second electrode 23 extend around the first substrate 1 outside the first sacrificial layer 121'.

[0052] The piezoelectric layer 22 can be deposited by any suitable method known to those skilled in the art, such as chemical vapor deposition, physical vapor deposition or atomic layer deposition. By forming the piezoelectric layer 22 on the flat first electrode 21, the upper surface and the lower surface of the piezoelectric layer 22 are both planes, thereby ensuring that the piezoelectric layer 22 has a good lattice orientation, improving the piezoelectric properties of the piezoelectric layer 22, and thus improving the overall performance of the resonator. It should be noted that the effective resonance area is the area surrounded by the first annular gap 32 formed subsequently.

[0053] The materials of the first electrode 21 and the second electrode 23 can be any suitable conductive material or semiconductor material known in the art, wherein the conductive material can be a metal material with conductive properties, for example, made of one of metals such as molybdenum (Mo), aluminum (Al), copper (Cu), tungsten (W), tantalum (Ta), platinum (Pt), ruthenium (Ru), rhodium (Rh), iridium (Ir), chromium (Cr), titanium (Ti), gold (Au), osmium (Os), rhenium (Re), palladium (Pd), or a stack of the above metals, and the semiconductor material can be, for example, Si, Ge, SiGe, SiC, SiGeC, etc. The material of the piezoelectric layer 22 can be piezoelectric materials having a wurtzite crystal structure such as aluminum nitride (AlN), zinc oxide (ZnO), lead zirconate titanate (PZT), lithium niobate (LiNbO3), quartz (Quartz), potassium niobate (KNbO3) or lithium tantalate (LiTaO3), and combinations thereof. When the material of the piezoelectric layer 22 is aluminum nitride (AlN), the piezoelectric layer 22 may further include a rare earth metal, such as at least one of scandium (Sc), erbium (Er), yttrium (Y) and lanthanum (La). In addition, when the material of the piezoelectric layer 22 is aluminum nitride (AlN), the piezoelectric layer 22 may further include a transition metal, such as at least one of zirconium (Zr), titanium (Ti), manganese (Mn) and hafnium (Hf).

[0054] Continue to refer to Figure 4In the present embodiment, after forming the second electrode 23, the second electrode 23 is etched to form a groove penetrating the second electrode 23, the piezoelectric layer 22 and the first electrode 21, wherein the portion of the groove penetrating the second electrode 23 and the first electrode 21 is an annular groove 24, and the portion of the groove penetrating the piezoelectric layer 22 is a first groove 25. The first electrode 21 and the second electrode 23 are penetrated by the groove to separate the first electrode 21 and the second electrode 23 at the groove, and then the separated first electrode 21 is electrically connected through the first electrode lead-out structure 3 formed on the first electrode 21, and the separated second electrode 23 is electrically connected through the second electrode lead-out structure 4 subsequently formed on the second electrode 23, thereby reducing the impedance of the first electrode 21 and the second electrode 23.

[0055] The annular groove 24 is opposite to the first annular sacrificial protrusion 32', so that after the first annular sacrificial protrusion 32' is removed to form the first annular gap 32, the annular groove 24 is opposite to the first annular gap 32, so that the edge of the first electrode 21 is exposed to the first annular gap 32, thereby achieving the effect of eliminating the electrode boundary noise in the effective resonance area, so as to improve the Q value of the resonator. It should be noted that when the annular groove 24 is opposite to the first annular gap 32, the projection of the annular groove 24 on the surface of the piezoelectric layer 22 partially overlaps with the projection of the first annular gap 32 on the surface of the piezoelectric layer 22; or, the projection of the annular groove 24 on the surface of the piezoelectric layer 22 is completely within the projection range of the first annular gap 32 on the surface of the piezoelectric layer 22. When the projection of the annular groove 24 on the surface of the piezoelectric layer 22 is completely within the projection range of the first annular gap 32 on the surface of the piezoelectric layer 22, the acoustic wave suppression effect is better.

[0056] In addition, the projections of the annular groove 24 and the first groove 25 on the surface of the piezoelectric layer 22 overlap each other, so that the edge of the piezoelectric layer 22 is exposed in the first annular gap 32, thereby effectively suppressing the acoustic wave loss of the piezoelectric layer 22. The first groove 25 is a closed annular shape, and the piezoelectric layer 22 inside the first annular gap 32 and the piezoelectric layer 22 outside the first annular gap 32 are isolated from each other; or, the first groove 25 is an intermittent annular shape, and the piezoelectric layer 22 inside the first annular gap 32 is isolated from the piezoelectric layer 22 outside the first annular gap 32 through the intermittent portion. When the first groove 25 is a closed annular shape, the effect of suppressing acoustic wave leakage is better.

[0057] Reference Figure 5After forming the second electrode 23, a second electrode lead-out structure 4 having a second arch bridge structure 41 is formed on the second electrode 23, and the second electrode lead-out structure 4 extends from the four sides of the effective resonance region to the first substrate 1 outside the first sacrificial layer 121'. Specifically, the second electrode is etched to form an annular groove 24, and the annular groove 24 is located within the first sacrificial layer 121'; the annular groove 24 is filled to form a second annular sacrificial protrusion 42', and the second annular sacrificial protrusion 42' covers the second electrode 23 in the peripheral area of ​​the annular groove 24; the second electrode lead-out structure 4 is formed on the second electrode 23, covering the second annular sacrificial protrusion 42', and extending to the first substrate 1 outside the first sacrificial layer 121', and the second electrode lead-out structure 4 covers at least part of the second electrode 23 located in the effective resonance region; the second annular sacrificial protrusion 42' is removed to form an annular gap and an annular groove. It should be noted that the second electrode lead-out structure 4 located on the second annular sacrificial protrusion 42' forms a second arch bridge 41 structure.

[0058] In this embodiment, the method for forming the second electrode lead-out structure 4 on the second electrode 23 includes: depositing a conductive material on the second electrode 23, the conductive material covering the second electrode 23 and the second annular sacrificial protrusion 4 formed on the second electrode 23; etching the conductive material, removing part of the conductive material in the area surrounded by the second annular sacrificial protrusion 42', forming the second electrode lead-out structure 4, and the second electrode lead-out structure 4 extends to the first substrate 1 outside the first sacrificial layer 121'. In other embodiments, the method for forming the second electrode lead-out structure 4 on the second electrode 23 includes: depositing a conductive material on the second electrode 23, forming the second electrode lead-out structure 4, the second electrode lead-out structure 4 covers the second electrode 23 and the second annular sacrificial protrusion 42' formed on the second electrode 23, and extends to the first substrate outside the first sacrificial layer 121'. In the actual manufacturing process, the second electrode lead-out structure 4 only needs to be used to connect the second electrode 23 disconnected by the annular groove, and the corresponding formation method can be selected according to the actual structure, which is not further limited in this application. The structure of the second electrode lead-out structure 4 and its positional relationship with the second electrode 23 may refer to the structure of the first electrode lead-out structure 3 and its positional relationship with the first electrode 21 , and will not be described in detail here.

[0059] It should be noted that the formed second electrode lead-out structure 4 has a second portion extending outside the effective resonance region to serve as an electrode connection end. The second electrode lead-out structure can partially extend from the periphery of the effective resonance region to the first substrate 1 outside the first sacrificial layer 121'; or extend entirely from the periphery of the effective resonance region to the first substrate 1 outside the first sacrificial layer 121'.

[0060] Since the second annular gap inside the second arch bridge structure 41 and the first annular gap inside the first arch bridge structure 31 both enclose an effective resonance region, in order to avoid the effective resonance regions enclosed by the corresponding annular gaps from being staggered, the first arch bridge structure 31 of the first electrode lead-out structure 3 and the second arch bridge structure 41 of the second electrode lead-out structure 4 are arranged opposite to each other, that is, the projections arranged on the second arch bridge structure 41 and the projections arranged on the first arch bridge structure 31 on the surface of the piezoelectric layer 22 are completely overlapped. In addition, since the overlapping portions of the first electrode lead-out structure 3 and the second electrode lead-out structure 4 extending to the first substrate 1 outside the first sacrificial layer 121' only serve to connect the external circuit and improve the strength of the resonator, the projections of the overlapping portions of the first electrode lead-out structure 3 and the second electrode lead-out structure 4 on the surface of the piezoelectric layer 22 can overlap, partially overlap, or not overlap at all.

[0061] The first electrode lead-out structure 3 and the second electrode lead-out structure 4 are at least partially staggered at the periphery of their corresponding arch bridge structures to avoid high-frequency coupling problems caused by potential floating, prevent the formation of parasitic capacitance, and thus improve the resonator quality factor. When the electrode lead-out structure arranged on the first electrode 21 and the electrode lead-out structure arranged on the second electrode 23 are completely staggered at the periphery of the annular gap, high-frequency coupling problems can be better avoided.

[0062] In other embodiments, the first electrode 21 may be etched to form an annular groove after forming the first electrode 21 and before forming the piezoelectric layer 22. A sacrificial material is filled in the annular groove, and its upper surface is kept flat with the first electrode 21. Then the piezoelectric layer 22 is formed thereon, and the second electrode 23 is formed; the second electrode 23 is etched to form a groove penetrating the second electrode 23 and the piezoelectric layer 22, wherein the portion penetrating the second electrode 23 is an annular groove, and the portion penetrating the piezoelectric layer 22 is a first groove. The remaining steps refer to the above-mentioned embodiment 1 and are not repeated here.

[0063] In other embodiments, the first electrode 21 may be etched to form an annular groove after the first electrode 21 is formed and before the piezoelectric layer 22 is formed. A sacrificial material is filled in the annular groove, and its upper surface is kept flat with the first electrode 21. Then a piezoelectric layer 22 is formed thereon; the piezoelectric layer 22 is etched to form a first groove penetrating the piezoelectric layer 22, the first groove being opposite to the annular groove formed on the first electrode 21; a sacrificial material is filled in the first groove, and its upper surface is flush with the upper surface of the piezoelectric layer 22. Then a second electrode 23 is formed thereon; the second electrode 23 is etched to form an annular groove penetrating the second electrode 23; a sacrificial material is filled in the annular groove of the second electrode 23 and the second electrode 23 covering the peripheral area of ​​the annular groove forms a second annular sacrificial protrusion; a second electrode lead-out structure 4 is formed on the second electrode 23, covering the second annular sacrificial protrusion 42'. The remaining steps refer to the above-mentioned embodiment 1 and are not repeated here.

[0064] Reference Figure 6 , remove the first sacrificial layer to form a first cavity 121. Specifically, a release hole is formed on the second electrode 23 that penetrates the second electrode 23, the piezoelectric layer 22 and the first electrode 21, so that the release hole extends to the first sacrificial layer, and the first sacrificial layer is removed through the release hole. In the process of removing the first sacrificial layer, a corresponding removal method is adopted according to the material of the first sacrificial layer. For example, when the material of the first sacrificial layer is polyimide or photoresist, it is removed by ashing. The ashing method is specifically that at a temperature of 250 degrees Celsius, oxygen reacts chemically with the sacrificial layer material through air, and the generated gas substances are volatilized. When the material of the first sacrificial layer is low-temperature silicon dioxide, hydrofluoric acid solvent is used to react with low-temperature silicon dioxide to remove it to form a first cavity 121. The shape of the first cavity 121 is the same as that of the first sacrificial layer. It should be noted that the first annular sacrificial protrusion 32' and the second annular sacrificial protrusion 42' can be removed simultaneously with the first sacrificial layer, or before or after the first sacrificial layer is removed. The removal method refers to the removal method of the first sacrificial layer, which will not be repeated here.

[0065] Example 2

[0066] Embodiment 2 provides a method for manufacturing a thin film bulk acoustic wave resonator. Figure 7This is a schematic diagram of the structure of a thin film bulk acoustic wave resonator manufactured according to the manufacturing method of the thin film bulk acoustic wave resonator of this embodiment. The difference between this embodiment and embodiment 1 is that the piezoelectric layer 22 in embodiment 1 is formed with a first groove 25, and the piezoelectric layer 22 in this embodiment is a complete film layer, and the step of etching the piezoelectric layer 22 in the above embodiment 1 is omitted, and the remaining steps refer to the above embodiment 1. Specifically: the piezoelectric layer 22 is not etched, and is a complete film layer, covering the first cavity 121 and extending to the first substrate 11 outside the first cavity 121, so as to ensure the structural strength of the resonator and improve the yield rate of the resonator.

[0067] Example 3

[0068] Embodiment 3 provides a method for manufacturing a thin film bulk acoustic wave resonator. The difference between this embodiment and embodiment 1 is that in embodiment 1, electrode lead-out structures are formed on both the first electrode 21 and the second electrode 23, while in embodiment 3, the electrode lead-out structure is formed only on the first electrode 21 or the second electrode 23. When the electrode lead-out structure is formed on the first electrode 21, the step of forming the second electrode lead-out structure 4 on the second electrode 23 in embodiment 1 can be omitted; when the electrode lead-out structure is formed on the second electrode 23, the step of forming the first electrode lead-out structure 3 on the first electrode 21 in embodiment 1 can be omitted. The structure of the thin film bulk acoustic wave resonator is described below by taking the formation of the first electrode lead-out structure 3 on the first electrode 21 as an example. The formation method of the second electrode lead-out structure 4 on the second electrode 23 can refer to the formation of the first electrode lead-out structure 3 on the first electrode 21, and will not be described in detail. Reference Figure 8 , Figure 8 FIG. 4 is a schematic diagram of the structure of a thin film bulk acoustic wave resonator manufactured according to the method for manufacturing a thin film bulk acoustic wave resonator of this embodiment.

[0069] In this embodiment, the first electrode lead-out structure 3 is formed and after the first electrode 21 and the piezoelectric layer 22 are formed, the piezoelectric layer 22 is etched to form a groove penetrating the piezoelectric layer 22 and the first electrode 21, wherein the portion penetrating the piezoelectric layer 22 is the first groove 25, and the portion penetrating the first electrode 21 is the annular groove 24; a sacrificial material is filled in the groove, and its upper surface is flush with the upper surface of the piezoelectric layer 22; and a second electrode 23 is formed on the piezoelectric layer 22. The remaining steps refer to Example 1 and are not repeated here. In other embodiments, after forming the first electrode 21, the first electrode 21 is etched to form an annular groove 24 passing through the first electrode 21; a sacrificial material is filled in the annular groove 24 so that its upper surface is flush with the upper surface of the first electrode 21; a piezoelectric layer 22 is then formed on the first electrode 21; the piezoelectric layer 22 is etched to form a first groove 25 passing through the piezoelectric layer 22; a sacrificial material is filled in the first groove 25 so that its upper surface is flush with the upper surface of the piezoelectric layer 22; and a second electrode 23 is then formed on the piezoelectric layer 2222.

[0070] In addition, when the electrode lead-out structure is formed on the second electrode 23, the annular groove 24 penetrating the second electrode 23 and the first groove 25 penetrating the piezoelectric layer 22 can be formed synchronously after the second electrode 23 is formed, refer to the above content. The remaining steps refer to Example 1 and are not repeated here. In other embodiments, the first groove 25 penetrating the piezoelectric layer 22 and the annular groove 24 penetrating the second electrode 23 can be formed after the piezoelectric layer 22 and the second electrode 23 are correspondingly formed, refer to the above for details. The remaining steps refer to Example 1 and are not repeated here.

[0071] It should be noted that the electrode lead-out structure and the corresponding electrode without the electrode lead-out structure are at least partially staggered at the periphery of the arch bridge structure to avoid high-frequency coupling problems caused by potential floating, prevent the formation of parasitic capacitance, and thus improve the quality factor of the resonator. When the electrode lead-out structure and the corresponding electrode without the electrode lead-out structure are completely staggered at the periphery of the arch bridge structure, high-frequency coupling problems can be better avoided. The corresponding electrode can be understood as, when the electrode lead-out structure is formed on the first electrode 21, the first electrode 21 is the corresponding electrode of the electrode lead-out structure; similarly, when the electrode lead-out structure is formed on the second electrode 23, the second electrode 23 is the corresponding electrode of the electrode lead-out structure.

[0072] Example 4

[0073] Embodiment 4 provides a method for manufacturing a thin film bulk acoustic wave resonator. Fig. 9 The structure diagram of the thin film bulk acoustic wave resonator manufactured according to the manufacturing method of the thin film bulk acoustic wave resonator of this embodiment is shown in FIG. The difference between this embodiment and embodiment 3 is that the piezoelectric layer 22 in embodiment 3 is formed with a first groove 25, and the piezoelectric layer 22 in this embodiment is a complete film layer. When the thin film bulk acoustic wave resonator is formed according to the steps of embodiment 3, the step of etching the piezoelectric layer 22 is omitted. The beneficial effect of the piezoelectric layer 22 being a complete film layer refers to the above embodiment 2, which will not be repeated here.

[0074] Example 5

[0075] Embodiment 5 of the present invention provides a filter, comprising at least one thin film bulk acoustic wave resonator as described above. The thin film bulk acoustic wave resonator is connected to form a filter to ensure that the filter has good structural stability, and because the electrode impedance of the resonator is low, the conductivity of the filter can be improved, and the accuracy of filtering can be improved.

[0076] It should be noted that the various embodiments in this specification are described in a related manner, and the same or similar parts between the various embodiments can be referred to each other, and each embodiment focuses on the differences from other embodiments. In particular, for the structural embodiment, since it is basically similar to the method embodiment, the description is relatively simple, and the relevant parts can be referred to the partial description of the method embodiment.

[0077] The above description is only a description of the preferred embodiments of the present invention, and is not intended to limit the scope of the present invention. Any changes or modifications made by a person skilled in the art in the field of the present invention based on the above disclosure shall fall within the scope of protection of the claims.

Claims

1. A method for manufacturing a thin film bulk acoustic resonator, characterized in that: include: forming a first substrate having a first sacrificial layer; forming a first electrode, a piezoelectric layer and a second electrode in sequence on the first substrate, wherein the first electrode covers the first sacrificial layer; An annular groove penetrating the corresponding electrode is formed on at least one of the first electrode and the second electrode; an electrode lead-out structure having an arched bridge structure is formed on the corresponding electrode having the annular groove, the arched bridge structure being opposite to the annular groove; The first sacrificial layer is removed to form a first cavity.

2. The method for manufacturing a thin film bulk acoustic wave resonator according to claim 1, characterized in that: The method of forming an electrode lead-out structure having an arch bridge structure on a corresponding electrode having the annular groove includes: The method for forming an electrode lead-out structure having an arch bridge structure on the first electrode having the annular groove includes: before forming the first electrode, forming the electrode lead-out structure having an arch bridge structure on the first sacrificial layer, wherein the electrode lead-out structure extends from the periphery of the effective resonance region to the first substrate at the periphery of the first sacrificial layer; and / or, The method for forming the electrode lead-out structure having an arched bridge structure on the second electrode formed in the annular groove comprises: after forming the second electrode, forming the electrode lead-out structure having the arched bridge structure on the second electrode, wherein the electrode lead-out structure extends from the four sides of the effective resonance area to the first substrate at the periphery of the first sacrificial layer.

3. The method for manufacturing a thin film bulk acoustic wave resonator according to claim 2, characterized in that: The method for forming the electrode lead-out structure having an arch bridge structure on the first sacrificial layer comprises: forming a first groove on the first sacrificial layer, wherein the first groove is located around the effective resonance area; forming a second groove in the first groove, wherein the depth of the second groove is greater than the depth of the first groove, and the second groove is located at the edge of the effective resonance area; forming the electrode lead-out structure in the first groove, wherein the electrode lead-out structure fills the first groove except the second groove; forming a first annular sacrificial protrusion on the electrode lead-out structure located in the second groove; forming a first electrode on the first substrate, covering the first sacrificial layer, the first annular sacrificial protrusion and the electrode lead-out structure; Etching the first electrode to form an annular groove; The first annular sacrificial protrusion is removed to form an annular gap.

4. The method for manufacturing a thin film bulk acoustic wave resonator according to claim 3, characterized in that: The second groove forms a closed ring shape.

5. The method for manufacturing a thin film bulk acoustic wave resonator according to claim 2, characterized in that: The method of forming the electrode lead-out structure having the arch bridge structure on the second electrode comprises: Etching the second electrode to form an annular groove, wherein the annular groove is located within the first sacrificial layer; Filling the annular groove to form a second annular sacrificial protrusion, wherein the second annular sacrificial protrusion covers the second electrode in the peripheral area of ​​the annular groove; forming an electrode lead-out structure on the second electrode, covering the second annular sacrificial protrusion and extending to the first substrate at the periphery of the first sacrificial layer, wherein the electrode lead-out structure covers at least a portion of the second electrode located in the effective resonance region; The second annular sacrificial protrusion is removed to form an annular gap and an annular groove.

6. The method for manufacturing a thin film bulk acoustic wave resonator according to claim 2, characterized in that: The first electrode and / or the second electrode extend around the first substrate at the periphery of the first sacrificial layer.

7. The method for manufacturing a thin film bulk acoustic wave resonator according to claim 2, characterized in that: One of the first electrode and the second electrode is provided with an electrode lead-out structure, and the electrode lead-out structure and the corresponding electrode without the electrode lead-out structure respectively have a first portion extending outside the effective resonance region, and the first portion serves as an electrode connection end.

8. The method for manufacturing a thin film bulk acoustic wave resonator according to claim 7, characterized in that: When forming the electrode lead-out structure, it also includes patterning the electrode lead-out structure. When forming a corresponding electrode without the electrode lead-out structure, it also includes patterning the corresponding electrode, so that the electrode lead-out structure and the corresponding electrode without the electrode lead-out structure are at least partially staggered with each other on the periphery of the arch bridge structure.

9. The method for manufacturing a thin film bulk acoustic wave resonator according to claim 3, characterized in that: The first electrode and the second electrode both form an electrode lead-out structure. The electrode lead-out structure disposed on the first electrode and the electrode lead-out structure disposed on the second electrode respectively have a second portion extending outside the effective resonance region, and the second portion serves as an electrode connection end.

10. The method for manufacturing a thin film bulk acoustic wave resonator according to claim 9, characterized in that: When forming the electrode lead-out structure, the method further includes patterning the electrode lead-out structure so that the electrode lead-out structure formed on the first electrode and the electrode lead-out structure formed on the second electrode are at least partially staggered with each other at the periphery of the annular gap; The arched bridge structure of the electrode lead-out structure formed on the first electrode is arranged opposite to the arched bridge structure of the electrode lead-out structure formed on the second electrode.

11. The method for manufacturing a thin film bulk acoustic wave resonator according to claim 1, characterized in that: The impedance of the electrode lead-out structure is lower than the impedance of the corresponding electrode.

12. The method for manufacturing a thin film bulk acoustic wave resonator according to claim 1, characterized in that: The material of the electrode lead-out structure is a metal material, and the metal material includes one or more of gold, silver, tungsten, platinum, aluminum, copper, titanium, tin, and nickel.

13. The method for manufacturing a thin film bulk acoustic resonator according to any one of claims 3 or 5, characterized in that: The annular space is a closed annular space.

14. The method for manufacturing a thin film bulk acoustic wave resonator according to claim 3, characterized in that: The formed piezoelectric layer covers the first cavity and extends to the periphery of the first cavity; or, After the piezoelectric layer is formed, the piezoelectric layer is etched to form a first groove penetrating the piezoelectric layer, wherein the first groove is opposite to the annular groove.

15. The method for manufacturing a thin film bulk acoustic wave resonator according to claim 14, characterized in that: The first groove is a closed ring, and the piezoelectric layer inside the ring gap and the piezoelectric layer outside the ring gap are isolated from each other; or, The first groove is in the shape of a discontinuous ring, and the piezoelectric layer inside the annular gap is isolated from the piezoelectric layer outside the annular gap by the discontinuity.

16. The method for manufacturing a thin film bulk acoustic wave resonator according to claim 1, characterized in that: The first substrate includes a support layer and a base, and the method for forming the first substrate having a first sacrificial layer includes: providing the substrate; forming a support layer on the substrate; Patterning the support layer to form a first cavity; The first cavity is filled to form a first sacrificial layer, wherein a first surface of the first sacrificial layer is flush with a first surface of the supporting layer.

17. The method for manufacturing a thin film bulk acoustic wave resonator according to claim 16, characterized in that: The first cavity extends to part of the thickness of the support layer; or, The first cavity penetrates the supporting layer.

18. The method for manufacturing a thin film bulk acoustic wave resonator according to claim 1, characterized in that: The material of the first sacrificial layer includes phosphosilicate glass, low temperature silicon dioxide, borophosphosilicate glass, germanium, amorphous carbon, polyimide or photoresist.

19. The method for manufacturing a thin film bulk acoustic wave resonator according to claim 1, characterized in that: The material of the first electrode or the second electrode includes: a combination of one or more of molybdenum, aluminum, copper, tungsten, tantalum, platinum, ruthenium, rhodium, iridium, chromium, titanium, gold, osmium, rhenium or palladium.

20. The method for manufacturing a thin film bulk acoustic wave resonator according to claim 1, characterized in that: The material of the piezoelectric layer includes: aluminum nitride, zinc oxide, lead zirconate titanate, lithium niobate, quartz, potassium niobate or lithium tantalate.

21. A filter, characterized in that: The invention comprises at least one film bulk acoustic wave resonator formed by the method for manufacturing a film bulk acoustic wave resonator according to any one of claims 1 to 20.

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