Method for manufacturing a thin film bulk acoustic wave resonator

Abstract

The present invention discloses a method for manufacturing a thin film bulk acoustic wave resonator, comprising: forming a first electrode, a second electrode and a piezoelectric layer, wherein the piezoelectric layer is located between the first electrode and the second electrode; forming a support layer on the first electrode; patterning the support layer to form a first cavity penetrating the support layer; forming a first substrate on the support layer, the first substrate covering the first cavity; at least one of the first electrode and the second electrode has an arch bridge, and the method for forming the electrode with the arch bridge comprises: forming an annular sacrificial protrusion; depositing a conductive material layer to cover the annular sacrificial protrusion and the surrounding area of ​​the annular sacrificial protrusion; removing the annular sacrificial protrusion to form an annular gap. The present invention uses the arch bridge structure of the electrode to surround the entire effective resonance area from the periphery of the effective resonance area, thereby improving the mechanical strength of the resonator.

Description

Technical Field

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

[0002] With the continuous development of wireless communication technology, in order to meet the multifunctional requirements of various wireless communication terminals, terminal equipment needs to be able to use different carrier spectra to transmit data. At the same time, in order to support sufficient data transmission rate within a limited bandwidth, strict performance requirements are also put forward for the RF system. RF filter is an important part of the RF system, which can filter out interference and noise outside the communication spectrum to meet the signal-to-noise ratio requirements of the RF system and communication protocol. Taking mobile phones as an example, since each frequency band requires a corresponding filter, dozens of filters may need to be set in a mobile phone.

[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 cavity-type thin film bulk acoustic wave resonators currently manufactured have problems such as shear wave loss and insufficient structural strength, which prevents the quality factor (Q) from being further improved and low yield rate, and therefore cannot meet the needs of high-performance RF 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, 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, comprising:

[0007] forming a first electrode, a second electrode and a piezoelectric layer, wherein the piezoelectric layer is located between the first electrode and the second electrode;

[0008] forming a supporting layer on the first electrode;

[0009] Patterning the support layer to form a first cavity penetrating the support layer;

[0010] forming a first substrate on the support layer, wherein the first substrate covers the first cavity;

[0011] At least one of the first electrode and the second electrode has an arch bridge, and a method for forming the electrode having the arch bridge includes:

[0012] An annular sacrificial protrusion is formed; a conductive material layer is deposited to cover the annular sacrificial protrusion and the surrounding area of ​​the annular sacrificial protrusion; and the annular sacrificial protrusion is removed to form an annular gap.

[0013] The beneficial effects of the present invention are as follows: the first electrode and / or the second electrode form an arch bridge structure, the arch bridge forms a closed ring, and the arch bridge and the surface of the plane where the piezoelectric layer is located form an annular gap, so that the ends of the first electrode and / or the second electrode at the boundary of the effective resonance area are in contact with the gas in the gap, thereby achieving the effect of eliminating the boundary noise of the electrode in the effective resonance area, thereby improving the Q value of the resonator.

[0014] Furthermore, the arched bridge structure of the electrode serves as a boundary of the effective resonance region, surrounding the entire effective resonance region. The electrode can extend from all sides of the effective resonance region to the first substrate, thereby improving the mechanical strength of the resonator.

[0015] Furthermore, the piezoelectric layer above the cavity is not etched to form a groove or hole structure (compared to the case where the piezoelectric layer has a groove), which can ensure the structural strength of the resonator and improve the yield of the resonator.

[0016] Furthermore, the projections of the first electrode and the second electrode in the outer peripheral area of ​​the arch bridge on the plane where the piezoelectric layer is located are staggered, which can avoid high-frequency coupling problems caused by potential floating, prevent the formation of parasitic capacitance, and help improve the quality factor of the resonator.

[0017] Furthermore, a 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 and improve the Q value of the resonator.

[0018] Furthermore, a first cavity is formed by etching the support layer, a first substrate is bonded on the support layer to cover the first cavity, an annular sacrificial protrusion is formed before forming the first electrode or the second electrode, and the annular sacrificial protrusion is removed to form an arch bridge structure, which is compatible with semiconductor technology and has a simple process flow. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] 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.

[0020] Figures 1 to 7The schematic diagram shows the structures corresponding to different steps of the method for manufacturing a thin film bulk acoustic wave resonator according to Example 1 of the present invention.

[0021] Figures 8 to 13 The schematic diagram shows the structures corresponding to different steps of the method for manufacturing a thin film bulk acoustic wave resonator according to the second embodiment of the present invention.

[0022] Figures 14 to 20 The schematic diagram of the structure corresponding to different steps of the method for manufacturing a thin film bulk acoustic wave resonator according to Embodiment 3 of the present invention is shown.

[0023] Figure 21 to Figure 26 The schematic diagram of the structure corresponding to different steps of the method for manufacturing a thin film bulk acoustic wave resonator according to Embodiment 4 of the present invention is shown.

[0024] Description of reference numerals:

[0025] 100a-first substrate; 100b-support layer; 101-first electrode; 102-piezoelectric layer; 103-second electrode; 200-first cavity; 201-sacrificial layer; 30-arch bridge; 31-annular sacrificial protrusion; 31-1-first annular sacrificial protrusion; 31-2-second annular sacrificial protrusion; 40-groove; 1000-carrying substrate. DETAILED DESCRIPTION

[0026] 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.

[0027] 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.

[0028] Example 1

[0029] Embodiment 1 of the present invention provides a method for manufacturing a thin film bulk acoustic wave resonator, comprising:

[0030] S01: forming a first electrode, a second electrode and a piezoelectric layer, wherein the piezoelectric layer is located between the first electrode and the second electrode;

[0031] S02: forming a supporting layer on the first electrode;

[0032] S03: patterning the support layer to form a first cavity penetrating the support layer;

[0033] S04: forming a first substrate on the support layer, wherein the first substrate covers the first cavity;

[0034] S05: At least one of the first electrode and the second electrode has an arch bridge, and a method for forming the electrode having the arch bridge includes:

[0035] An annular sacrificial protrusion is formed; a conductive material layer is deposited to cover the annular sacrificial protrusion and the surrounding area of ​​the annular sacrificial protrusion; and the annular sacrificial protrusion is removed to form an annular gap.

[0036] It should be noted that steps S0N do not represent a sequential order.

[0037] Figures 1 to 7 Schematic diagram of the structure corresponding to each step of the method for manufacturing the thin film bulk acoustic wave resonator of this embodiment. Figures 1 to 7 The manufacturing method of thin film bulk acoustic wave resonator is explained.

[0038] refer to Figures 1 to 3 In this embodiment, the method of forming the first electrode 101, the second electrode 103 and the piezoelectric layer 102 includes:

[0039] A carrier substrate 1000 is provided, and a second electrode 103 is formed on the carrier substrate 1000 ; a piezoelectric layer 102 is formed on the second electrode 103 ; and a first electrode 101 is formed on the piezoelectric layer 102 , wherein the first electrode 101 is formed with an arch bridge structure 30 .

[0040] Specifically, refer to Figure 1, provide a carrier substrate 1000, the carrier substrate can be a semiconductor material, such as 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 second electrode 103 can be formed on the carrier substrate by a physical vapor deposition process, and the material of the second electrode 103 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 the 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 stacked layer formed by the above metals, and the semiconductor material is, for example, Si, Ge, SiGe, SiC, SiGeC, etc. The piezoelectric layer 102 may be formed by deposition using any suitable method known to those skilled in the art, such as chemical vapor deposition, physical vapor deposition, or atomic layer deposition, to cover the second electrode 103. The material of the piezoelectric layer 102 may be a piezoelectric material 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 a combination thereof. When the material of the piezoelectric layer 102 is aluminum nitride (AlN), the piezoelectric layer 102 may also include a rare earth metal, such as scandium (Sc), erbium (Er), yttrium (Y), and lanthanum (La). In addition, when the material of the piezoelectric layer 102 is aluminum nitride (AlN), the piezoelectric layer 102 may also include a transition metal, such as at least one of zirconium (Zr), titanium (Ti), manganese (Mn), and hafnium (Hf).

[0041] refer to Figure 2 , a sacrificial layer material is deposited on the piezoelectric layer 102, and the sacrificial layer material includes: phosphosilicate glass, low-temperature silicon dioxide, borophosphosilicate glass, germanium, carbon, polyimide or photoresist. The patterned sacrificial layer material forms an annular sacrificial protrusion 31, and the sacrificial protrusion 31 is a continuous structure, forming a closed ring. In this embodiment, the boundary of the ring defines the boundary of the effective resonance area of ​​the resonator. In this embodiment, the shape of the effective resonance area is an irregular polygon. In other embodiments, the effective resonance area can also be a circle or an ellipse or an irregular figure composed of arcs and straight lines.

[0042] refer to Figure 3, forming the first electrode 101, covering the annular sacrificial protrusion 31 and the piezoelectric layer 102, wherein the first electrode 101 above the annular sacrificial protrusion 31 forms an arch bridge 30 structure. The material and formation method of the first electrode 101 refer to the material and formation method of the second electrode 103. In this embodiment, the height of the annular sacrificial protrusion 31 is greater than the thickness of the first electrode 101. In other embodiments, the height of the annular sacrificial protrusion 31 ( Figure 3 The distance H1 between the two arrows in the figure is the height of the annular sacrificial protrusion 31) and can be equal to the thickness of the first electrode ( Figure 3 The distance H2 between the two arrows in the figure is the thickness of the first electrode) or is greater than the thickness of the first electrode. In the subsequent process, the annular sacrificial protrusion 31 will be removed to form an annular gap. The minimum height of the annular sacrificial protrusion 31 should satisfy that the resonance of the resonator cannot be achieved here, so as to achieve the purpose of defining the boundary of the effective resonance zone. In this embodiment, the gap height is greater than the thickness of the first electrode 101, so that the end of the first electrode 101 at the boundary of the effective resonator can be completely exposed in the gap, which better prevents the lateral sound waves from leaking from the first electrode 101 and improves the quality factor of the resonator. In addition, the arched bridge 30 structure of the first electrode 101 surrounds the entire effective resonance zone from the periphery of the effective resonance zone, thereby improving the mechanical strength of the resonator.

[0043] refer to Figure 4 The support layer 100b is formed to cover the first electrode 101. The material of the support layer 100b includes a dielectric material such as silicon dioxide, silicon nitride, aluminum oxide, aluminum nitride, silicon oxynitride or silicon carbonitride. The support layer 100b can be formed by a chemical vapor deposition process.

[0044] refer to Figure 5 , the support layer 100b is etched to form a first cavity 200, the bottom of the first cavity 200 exposes the first electrode 101, and the boundary of the first cavity 200 surrounds the boundary where the arch bridge 30 is located. The cross-sectional shape of the first cavity 200 can be circular, elliptical or polygonal. The etching process can be dry etching or wet etching. The dry etching process includes but is not limited to reactive ion etching, ion beam etching, plasma etching or laser cutting. After the first cavity 200 is formed, the annular sacrificial protrusion is removed. The method of removing the annular sacrificial protrusion can be selected according to the material of the annular sacrificial protrusion. When the material of the annular sacrificial protrusion is polyimide or photoresist, it is removed by ashing. The ashing method is specifically that at a temperature of 250 degrees Celsius, the oxygen in the release hole reacts chemically with the annular sacrificial protrusion material, and the generated gas substance volatilizes. When the annular sacrificial protrusion material is low-temperature silicon dioxide, it is removed by reacting with hydrofluoric acid solvent and low-temperature silicon dioxide. The release hole can be formed in the edge area of ​​the first cavity.

[0045] refer to Figure 6, a first substrate 100a is formed on the supporting layer 100b, and the first substrate 100a covers the first cavity 200. The supporting layer 100b can be combined with the first substrate 100a by bonding, and the bonding method includes: covalent bonding, adhesive bonding or melt bonding. In this embodiment, the method of forming the first substrate 100a on the supporting layer 100b is: forming a bonding layer on the supporting layer 100b or the first substrate 100a, and bonding the first substrate and the supporting layer through the bonding layer to cover the first cavity. The material of the bonding layer includes silicon oxide, silicon nitride, silicon oxynitride, silicon carbonitride or ethyl silicate. The material of the first substrate 100a can be a semiconductor material, and the specific material can refer to the material of the carrier substrate 1000.

[0046] refer to Figure 7 , remove the carrier substrate to expose the second electrode 103. In this embodiment, the second electrode is further patterned so that the projections of the first electrode 101 and the second electrode 103 in the direction of the first substrate are staggered at the periphery of the arch bridge ( Figure 7 The projections of the two are staggered in some areas). The staggered projections can avoid the high-frequency coupling problem caused by the floating potential, prevent the formation of parasitic capacitance, and help improve the quality factor of the resonator. In another embodiment, the first electrode and the second electrode can also be patterned so that the projections of the first electrode and the second electrode outside the effective resonance area are staggered. In another embodiment, the first electrode 101 and the second electrode 103 extend from the periphery of the effective resonance area to the first substrate 100 outside the first cavity 200, thereby ensuring the structural strength of the resonator and improving the yield rate.

[0047] The carrier substrate may be removed by a grinding process or a wet etching process, or a release layer may be formed on the carrier substrate before forming the second electrode 103, and the carrier substrate may be peeled off by removing the release layer. The material of the release layer includes but is not limited to at least one of silicon dioxide, silicon nitride, aluminum oxide, aluminum nitride, or thermal expansion tape.

[0048] In this embodiment, the upper surface and the lower surface of the piezoelectric layer 102 are both planes, so that the piezoelectric layer 102 has a good lattice orientation, the piezoelectric properties of the piezoelectric layer 102 are improved, and the overall performance of the resonator is improved.

[0049] In this embodiment, the area where the arch bridge 30 is located constitutes the boundary of the effective resonance area. In other embodiments, the boundary of the effective resonance area can be defined by other structures, and the arch bridge structure is arranged at the periphery of the effective resonance area. The technical effect is written after the structure.

[0050] Example 2

[0051] Figures 8 to 13 Schematic diagram of the structure corresponding to each step of the method for manufacturing the thin film bulk acoustic wave resonator of this embodiment. Figures 8 to 13 The manufacturing method of the thin film bulk acoustic wave resonator is described. The difference between this embodiment and the first embodiment is that a groove 40 is formed in the piezoelectric layer 102 .

[0052] Reference Figure 8 , provide a carrier substrate 1000, form a second electrode 103 on the carrier substrate 1000; and form a piezoelectric layer 102 on the second electrode 103. Regarding the material of the carrier substrate 1000, the material and formation method of the second electrode 103 and the piezoelectric layer 102, refer to Example 1, and will not be repeated here. After the piezoelectric layer 102 is formed, a groove 40 is formed in the piezoelectric layer 102. The groove 40 can be formed by a dry etching process, and the dry etching process includes but is not limited to reactive ion etching, ion beam etching, plasma etching or laser cutting. In this embodiment, the groove 40 is a closed ring and runs through the piezoelectric layer 102, and the inner side wall of the groove 40 coincides with the boundary of the effective resonance zone of the resonator. In other embodiments, the groove 40 can also be an intermittent ring structure or a non-ring structure, such as only setting a certain side boundary of the effective resonance zone. At this time, the piezoelectric layer in the effective resonance zone is connected to the piezoelectric layer outside the effective resonance zone through the discontinuity. In other embodiments, the groove 40 can also be set on the outside of the effective resonance zone. A groove 40 is formed in the piezoelectric layer 102 so that the end surface of the piezoelectric layer 102 forms a reflection interface with the gas in the groove 40, so as to effectively suppress the shear wave leakage in the piezoelectric layer 102 and improve the quality factor of the resonator. The groove 40 may not penetrate the piezoelectric layer 102. It can be understood that when the groove 40 is a closed ring and penetrates the piezoelectric layer 102, and the side wall of the groove 40 coincides with the boundary of the effective resonance area, the effect of suppressing the shear wave leakage is the best.

[0053] refer to Fig. 9 , forming a sacrificial material layer, covering the piezoelectric layer 102, the sacrificial material layer is filled into the groove, the material and formation method of the sacrificial material layer refer to Example 1, the sacrificial material layer is patterned, and an annular sacrificial protrusion 31 is formed above the groove. Regarding the structure of the annular sacrificial protrusion 31, refer to Example 1 for height.

[0054] refer to Fig.10 , forming a first electrode 101, covering the annular sacrificial protrusion 31 and the piezoelectric layer 102, wherein the first electrode 101 above the annular sacrificial protrusion 31 forms an arch bridge 30 structure. The material and formation method of the first electrode 101 refer to Example 1, which will not be repeated here.

[0055] refer to Fig.11The support layer 100b is formed to cover the first electrode 101. The material of the support layer 100b includes a dielectric material such as silicon dioxide, silicon nitride, aluminum oxide, aluminum nitride, silicon oxynitride or silicon carbonitride. The support layer 100b can be formed by a chemical vapor deposition process.

[0056] refer to Fig.12 , the supporting layer 100b is etched to form a first cavity 200, the bottom of the first cavity 200 exposes the first electrode 101, and the boundary of the first cavity 200 surrounds the boundary where the arch bridge 30 is located. After the first cavity 200 is formed, the annular sacrificial protrusion and the sacrificial material located in the groove are removed. In this embodiment, the annular sacrificial protrusion is in contact with the sacrificial material in the groove, and the materials used for both are the same, and can be removed at one time. The removal method refers to Example 1. After the sacrificial material is removed, an annular gap is formed at the position of the annular sacrificial protrusion, and the annular gap is connected to the groove. A first substrate 100a is formed on the supporting layer 100b, and the first substrate 100a covers the first cavity 200. The shape and formation method of the first cavity and the method of forming the first substrate 100a on the supporting layer 100b are all referred to Example 1, and will not be repeated here.

[0057] refer to Fig.13 , remove the carrier substrate to expose the second electrode 103. The method for removing the carrier substrate refers to Example 1. In this embodiment, the second electrode is also patterned so that the projections of the first electrode 101 and the second electrode 103 in the direction of the first substrate are staggered on the periphery of the arch bridge. The benefits of this arrangement and other structural forms of the first electrode and the second electrode refer to Example 1 and are not repeated here. In this embodiment, the annular gap and the groove are interconnected. In other embodiments, the annular gap and the groove can be isolated from each other, such as by defining the boundary of the effective resonance zone by the side wall of the groove, and the annular gap is arranged on the periphery of the groove.

[0058] Example 3

[0059] Figures 14 to 20 Schematic diagram of the structure corresponding to each step of the method for manufacturing the thin film bulk acoustic wave resonator of this embodiment. Figures 14 to 20 The manufacturing method of the thin film bulk acoustic wave resonator is described. In this embodiment, the first electrode, the piezoelectric layer and the second electrode are formed in different orders, and both the first electrode and the second electrode are formed with an arch bridge.

[0060] refer to Fig.14 A carrier substrate 1000 is provided, and a piezoelectric layer 102 is formed on the carrier substrate 1000. A groove 40 is formed in the piezoelectric layer 102. The material of the carrier substrate 1000, the material and the forming method of the piezoelectric layer 102 refer to Example 1, and the structure and the forming method of the groove 40 refer to Example 2.

[0061] refer to Fig.15 , forming a sacrificial material layer, covering the piezoelectric layer 102, the sacrificial material layer is filled into the groove, the material and formation method of the sacrificial material layer refer to Example 1, the sacrificial material layer is patterned, and a first annular sacrificial protrusion 31-1 is formed above the groove. Regarding the structure of the first annular sacrificial protrusion 31-1, the height refers to the annular sacrificial protrusion of Example 1.

[0062] refer to Fig.16 , forming a first electrode 101, covering the first annular sacrificial protrusion 31-1 and the piezoelectric layer 102, wherein the first electrode 101 above the first annular sacrificial protrusion 31-1 forms an arch bridge 30 structure. The material and formation method of the first electrode 101 refer to the first embodiment.

[0063] refer to Fig.17 The support layer 100b is formed to cover the first electrode 101. The material of the support layer 100b includes a dielectric material such as silicon dioxide, silicon nitride, aluminum oxide, aluminum nitride, silicon oxynitride or silicon carbonitride. The support layer 100b can be formed by a chemical vapor deposition process.

[0064] refer to Fig.18 , the supporting layer 100b is etched to form a first cavity 200, the bottom of the first cavity 200 exposes the first electrode 101, and the boundary of the first cavity 200 surrounds the boundary where the arch bridge 30 is located. After the first cavity 200 is formed, the annular sacrificial protrusion and the sacrificial material located in the groove are removed. After the sacrificial material is removed, an annular gap is formed at the position of the annular sacrificial protrusion, and the annular gap is connected to the groove. The method for removing the sacrificial material is referred to Example 2. A first substrate 100a is formed on the supporting layer 100b, and the first substrate 100a covers the first cavity 200. The shape and formation method of the first cavity and the method for forming the first substrate 100a on the supporting layer 100b are all referred to Example 1.

[0065] refer to Fig.19 , remove the carrier substrate to expose the piezoelectric layer 102. The method of removing the carrier substrate is referred to Example 1. In this embodiment, the groove runs through the piezoelectric layer 102. After removing the carrier substrate, a sacrificial material layer is formed to cover the piezoelectric layer 102 and the sacrificial material in the groove. The material and formation method of the sacrificial material layer are referred to Example 1. The sacrificial material layer is patterned to form a second annular sacrificial protrusion 31-2 above the groove. The structure and height of the second annular sacrificial protrusion 31-2 are referred to the first annular sacrificial protrusion 31-1.

[0066] refer to Fig. 20, forming a second electrode 103, covering the second annular sacrificial protrusion 31-2 and the piezoelectric layer 102, wherein the second electrode 103 above the second annular sacrificial protrusion 31-2 forms an arch bridge 30 structure. The material and formation method of the second electrode 103 refer to the material and formation method of the second electrode 103. Remove the first annular sacrificial protrusion, the second annular sacrificial protrusion and the sacrificial material in the groove. In this embodiment, the three are connected and can be removed at one time. The removal method can refer to Example 2. The arch bridge 30 of the first electrode 101 and the arch bridge 30 of the second electrode 103 of this embodiment are arranged opposite to each other, and the annular gap and the groove formed by the two arch bridges are interconnected.

[0067] Example 4

[0068] Figure 21 to Figure 26 Schematic diagram of the structure corresponding to each step of the method for manufacturing the thin film bulk acoustic wave resonator of this embodiment. Figure 21 to Figure 26 The manufacturing method of the thin film bulk acoustic wave resonator is described. In this embodiment, the order of forming the first electrode, the piezoelectric layer and the second electrode is different. The material, structure and formation method of the film layer involved in this embodiment refer to the above three embodiments, and this embodiment only describes the manufacturing steps.

[0069] refer to Fig.21 , providing a carrier substrate 1000, forming a sacrificial material layer on the carrier substrate 1000, and patterning the sacrificial material layer to form a first annular sacrificial protrusion 31 - 1.

[0070] refer to Fig. 22 , forming a first electrode 101 to cover the first annular sacrificial protrusion 31 - 1 and the carrier substrate 1000 . The formed first electrode 101 has an arch bridge 30 .

[0071] refer to Fig.23 , forming a support layer 100 b , etching the support layer 100 b to form a first cavity 200 , the bottom of the first cavity 200 exposes the first electrode 101 , and the boundary of the first cavity 200 surrounds the boundary where the arch bridge 30 is located.

[0072] refer to Fig.24 , a first substrate 100 a is formed on the support layer 100 b , and the first substrate 100 a covers the first cavity 200 .

[0073] refer to Fig.25 , remove the carrier substrate to expose the piezoelectric layer 102. Form a sacrificial material layer to cover the piezoelectric layer 102, pattern the sacrificial material layer to form a first annular protrusion 31-2. In this embodiment, the first annular sacrificial protrusion and the second annular sacrificial protrusion are arranged opposite to each other.

[0074] refer to Fig.26, forming a second electrode 103, covering the second annular sacrificial protrusion 31-2 and the piezoelectric layer 102, wherein the second electrode 103 above the second annular sacrificial protrusion 31-2 forms an arch bridge 30 structure. The first annular sacrificial protrusion and the second annular sacrificial protrusion are removed.

[0075] In the methods of the above embodiments, one or both of the first electrode and the second electrode may form an arch bridge, and grooves may or may not be formed in the piezoelectric layer. The above embodiments are just examples to illustrate several situations.

[0076] To sum up, the first electrode and / or the second electrode of the present invention forms an arch bridge structure, the arch bridge forms a closed ring, and the arch bridge and the surface of the plane where the piezoelectric layer is located form an annular gap, so that the ends of the first electrode and / or the second electrode at the boundary of the effective resonance zone are in contact with the gas in the gap, thereby achieving the effect of eliminating the boundary noise of the electrodes in the effective resonance zone, thereby improving the Q value of the resonator.

[0077] Furthermore, the arched bridge structure of the electrode serves as the boundary of the effective resonance region, surrounding the entire effective resonance region, and the electrode can extend from all sides of the effective resonance region to the first substrate, which not only improves the mechanical strength of the resonator but also reduces the impedance of the electrode.

[0078] Furthermore, the piezoelectric layer above the cavity is not etched to form a groove or hole structure (compared to the case where a groove is provided in the piezoelectric layer), which can ensure the structural strength of the resonator and improve the yield rate of the resonator.

[0079] Furthermore, the projections of the first electrode and the second electrode in the outer peripheral area of ​​the arch bridge on the plane where the piezoelectric layer is located are staggered, which can avoid high-frequency coupling problems caused by potential floating, prevent the formation of parasitic capacitance, and help improve the quality factor of the resonator.

[0080] Furthermore, a 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 and improve the Q value of the resonator.

[0081] Furthermore, a first cavity is formed by etching the support layer, a first substrate is bonded on the support layer to cover the first cavity, an annular sacrificial protrusion is formed before forming the first electrode or the second electrode, and the annular sacrificial protrusion is removed to form an arch bridge structure, which is compatible with semiconductor technology and has a simple process flow.

[0082] 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 referenced to each other, and each embodiment focuses on the differences from other embodiments.

[0083] 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 electrode, a second electrode and a piezoelectric layer, wherein the piezoelectric layer is located between the first electrode and the second electrode; forming a supporting layer on the first electrode; Patterning the support layer to form a first cavity penetrating the support layer; forming a first substrate on the support layer, wherein the first substrate covers the first cavity; At least one of the first electrode and the second electrode has an arched bridge, the arched bridge forms a closed ring, the arched bridge and the surface of the piezoelectric layer form an annular gap, the arched bridge of the electrode serves as a boundary of the effective resonance area, surrounding the entire effective resonance area, and the method for forming the electrode with the arched bridge includes: A continuous and closed annular sacrificial protrusion is formed; a conductive material layer is deposited to cover the annular sacrificial protrusion and the surrounding area of ​​the annular sacrificial protrusion; and the annular sacrificial protrusion is removed to form an annular gap.

2. The method for manufacturing a thin film bulk acoustic wave resonator according to claim 1, characterized in that: The method of forming the first electrode, the second electrode and the piezoelectric layer comprises: Providing a carrier substrate; forming a first electrode on the carrier substrate; After forming the first substrate, removing the carrier substrate, and forming a piezoelectric layer on a side of the first electrode opposite to the first cavity; forming a second electrode on the piezoelectric layer; or, Providing a carrier substrate; forming a piezoelectric layer on the carrier substrate; forming a first electrode on the piezoelectric layer; After forming the first substrate, removing the carrier substrate, and forming a second electrode on the piezoelectric layer; or Providing a carrier substrate; forming a second electrode on the carrier substrate; forming a piezoelectric layer on the second electrode; forming a first electrode on the piezoelectric layer; After forming the first substrate, the carrier substrate is removed.

3. The method for manufacturing a thin film bulk acoustic wave resonator according to claim 1, characterized in that: Forming the piezoelectric layer comprises: The formed piezoelectric layer covers the first cavity and extends outside the first cavity; or, After forming the piezoelectric layer, a groove is formed in the piezoelectric layer, wherein the groove is opposite to the arch bridge.

4. The method for manufacturing a thin film bulk acoustic wave resonator according to claim 3, characterized in that: The groove is a closed ring, or The grooves are arranged discontinuously, and the piezoelectric layer in the effective resonance region is connected to the piezoelectric layer outside the effective resonance region through the discontinuities.

5. The method for manufacturing a thin film bulk acoustic wave resonator according to claim 1, characterized in that: The first electrode and the second electrode are both provided with the arched bridge, and the arched bridge of the first electrode is arranged opposite to the arched bridge of the second electrode.

6. The method for manufacturing a thin film bulk acoustic wave resonator according to claim 1, characterized in that: The first electrode or the second electrode extends from the periphery of the effective resonance region to the first substrate; or, both the first electrode and the second electrode extend from the periphery of the effective resonance region to the first substrate.

7. The method for manufacturing a thin film bulk acoustic wave resonator according to claim 1, characterized in that: After forming the first electrode and the second electrode, the method further includes patterning the first electrode and the second electrode so that the projections of the first electrode and the second electrode in the direction of the first substrate are staggered on the periphery of the arch bridge.

8. The method for manufacturing a thin film bulk acoustic wave resonator according to claim 1, characterized in that: The material of the support layer includes: silicon dioxide, silicon nitride, aluminum oxide or aluminum nitride, silicon oxynitride, and silicon carbonitride.

9. 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.

10. 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.

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

12. The method for manufacturing a thin film bulk acoustic wave resonator according to claim 1, characterized in that: The forming of a first substrate on the supporting layer comprises: A bonding layer is formed on the support layer or the first substrate, and the first substrate and the support layer are bonded via the bonding layer to cover the first cavity.

13. The method for manufacturing a thin film bulk acoustic wave resonator according to claim 12, characterized in that: The material of the bonding layer includes silicon oxide, silicon nitride, silicon oxynitride, silicon carbonitride or ethyl silicate.

14. The method for manufacturing a thin film bulk acoustic wave resonator according to claim 2, characterized in that: The material of the carrier substrate or the first substrate includes semiconductor material.

Images