A high-power capacity bulk acoustic wave resonator and its preparation method
By providing the first titanium tungsten alloy layer on the top electrode of the bulk acoustic wave resonator, the problem that the bulk acoustic wave resonator cannot increase the working frequency and power capacity at the same time is solved, and the effect of improving power resistance and power capacity is achieved.
Patent Information
- Application Number
- CN202411541121.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2024-10-31
- Publication Date
- 2025-03-14
- Estimated Expiration
- 2044-10-31
AI Technical Summary
The working frequency of the bulk acoustic resonator is negatively correlated with the electrode thickness and area, and the power capacity is positively correlated with the electrode thickness and area, which makes it impossible to increase the working frequency and power capacity at the same time.
A first titanium tungsten alloy layer is provided on the top electrode to prevent the migration and diffusion of metal atoms using its good thermal stability, hardness and density, thereby improving the power resistance and power capacity of the bulk acoustic wave resonator.
It effectively improves the power capacity and operating frequency of the bulk acoustic wave resonator, solving the problem that the working frequency and power capacity cannot be increased at the same time.
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Figure CN119070777B_ABST
Abstract
Description
Technical Field
[0001] The present application relates to the technical field of bulk acoustic wave resonators, and in particular to a high-power capacity bulk acoustic wave resonator and a preparation method thereof. Background Art
[0002] BAW resonators are widely used in the field of 5G communication technology. 5G communication requires BAW resonators to have the characteristics of high operating frequency and high power capacity. Since the operating frequency of the BAW resonator is negatively correlated with the electrode thickness and electrode area of the BAW resonator, that is, to meet the demand for high operating frequency of the BAW resonator, the electrode thickness and electrode area of the BAW resonator need to be small, while the power capacity of the BAW resonator is positively correlated with the electrode thickness and electrode area of the BAW resonator, that is, to meet the demand for high power capacity of the BAW resonator, the electrode thickness and electrode area of the BAW resonator need to be large. Therefore, the related technology has the problem that the operating frequency and power capacity of the BAW resonator cannot be improved at the same time because the operating frequency of the BAW resonator is negatively correlated with the electrode thickness and electrode area of the BAW resonator, and the power capacity of the BAW resonator is positively correlated with the electrode thickness and electrode area of the BAW resonator.
[0003] There is no effective technical solution to the above problems. It should be noted that the above information disclosed in this section is only used to understand the background of the present invention, and therefore may contain information that does not constitute prior art. Summary of the invention
[0004] The purpose of the present application is to provide a high-power capacity BAW resonator and a preparation method thereof, which can effectively solve the problem that the operating frequency and power capacity of the BAW resonator cannot be increased simultaneously because the operating frequency of the BAW resonator is negatively correlated with the electrode thickness and electrode area of the BAW resonator, and the power capacity of the BAW resonator is positively correlated with the electrode thickness and electrode area of the BAW resonator.
[0005] In a first aspect, the present application provides a high-power capacity bulk acoustic wave resonator, comprising:
[0006] A substrate, a bottom electrode, a piezoelectric layer, a top electrode and a functional layer are connected in sequence from bottom to top, and an acoustic reflector is arranged on the substrate;
[0007] The functional layer includes a first titanium-tungsten alloy layer;
[0008] The outer boundary of the projection of the first titanium-tungsten alloy layer in the top view direction is located within the outer boundary of the projection of the top electrode in the top view direction, and the distance between the outer boundary of the projection of the first titanium-tungsten alloy layer in the top view direction and the outer boundary of the projection of the top electrode in the top view direction is greater than 0.
[0009] The present application provides a high-power capacity BAW resonator, in which a first titanium-tungsten alloy layer is arranged on a top electrode. Since the titanium-tungsten alloy has the advantages of good thermal stability, high hardness, high density and low atomic mobility, the present application can utilize the good thermal stability, hardness and density of the first titanium-tungsten alloy layer to block the migration and diffusion of metal atoms of the top electrode at high temperature. Therefore, the present application can utilize the first titanium-tungsten alloy layer to effectively improve the power resistance of the BAW resonator, thereby effectively improving the power capacity of the BAW resonator, so that the BAW resonator meets the demand for high power capacity. The first titanium-tungsten alloy layer is used to effectively improve the power capacity of the BAW resonator, that is, the present application can set the top electrode to have a small electrode thickness and a small electrode area so that the BAW resonator can meet the requirements of high operating frequency. Therefore, the present application can simultaneously improve the working efficiency and power capacity of the BAW resonator, thereby effectively solving the problem that the operating frequency of the BAW resonator and the electrode thickness and electrode area of the BAW resonator are negatively correlated, and the power capacity of the BAW resonator is positively correlated with the electrode thickness and electrode area of the BAW resonator, resulting in the inability to simultaneously improve the operating frequency and power capacity of the BAW resonator.
[0010] Optionally, one side of the top electrode extends outside the acoustic reflector, and the functional layer further includes a second titanium-tungsten alloy layer, and the second titanium-tungsten alloy layer extends along one side of the top electrode outside the acoustic reflector.
[0011] Since the second titanium-tungsten alloy layer extends outside the acoustic reflector along one side of the top electrode, this technical solution is equivalent to increasing the cross-sectional area of the external circuit of the BAW resonator, thereby effectively reducing the resistance of the external circuit of the BAW resonator, and further effectively reducing the circuit loss of the external circuit of the BAW resonator.
[0012] Optionally, the distance between the first titanium-tungsten alloy layer and the second titanium-tungsten alloy layer is a first distance, the distance between the first titanium-tungsten alloy layer and the top electrode is a second distance, and both the first distance and the second distance are within 0.5-5 μm.
[0013] Optionally, the functional layer also includes several first conductive metal layers and several second conductive metal layers, the first conductive metal layer is arranged on the first titanium tungsten alloy layer, and the outer boundary of the projection of the first conductive metal layer in the top view direction is located within the outer boundary of the projection of the first titanium tungsten alloy layer in the top view direction, and the second conductive metal layer is arranged on the second titanium tungsten alloy layer, and the outer boundary of the projection of the second conductive metal layer in the top view direction is located within the outer boundary of the projection of the second titanium tungsten alloy layer in the top view direction.
[0014] Optionally, the electrical conductivity of the first conductive metal layer is greater than the electrical conductivity of the first titanium-tungsten alloy layer and the top electrode, and the electrical conductivity of the second conductive metal layer is greater than the electrical conductivity of the second titanium-tungsten alloy layer and the top electrode.
[0015] Optionally, the high-power BAW resonator further includes a passivation layer, wherein the passivation layer is disposed on the functional layer.
[0016] Since the outer boundary of the projection of the first conductive metal layer in the top-view direction of the technical scheme is located within the outer boundary of the projection of the first titanium-tungsten alloy layer in the top-view direction, and the outer boundary of the projection of the second conductive metal layer in the top-view direction is located at the outer boundary of the projection of the second titanium-tungsten alloy layer in the top-view direction, that is, the passivation layer can contact part of the top surface of the first titanium-tungsten alloy layer and part of the top surface of the second titanium-tungsten alloy layer, and titanium-tungsten alloy has good adhesion to both metal electrodes and dielectric materials. Therefore, this technical scheme can effectively avoid the situation where the passivation layer falls off in subsequent processing or a gap is generated between the passivation layer and the top electrode due to insufficient adhesion of the passivation layer on the top electrode, thereby effectively avoiding the situation where the performance of the bulk acoustic wave resonator is affected by the fall-off of the passivation layer or the gap between the passivation layer and the top electrode.
[0017] Optionally, the passivation layer does not cover the gap between the first titanium-tungsten alloy layer and the top electrode and the gap between the first titanium-tungsten alloy layer and the second titanium-tungsten alloy layer.
[0018] This technical solution is equivalent to increasing the depth of the groove formed on the top electrode to increase the difference between the acoustic impedance of the active area of the BAW resonator located in the first titanium-tungsten alloy layer and the acoustic impedance of the active area of the BAW resonator located outside the first titanium-tungsten alloy layer. Therefore, this technical solution can further suppress the noise at the series resonance frequency, thereby effectively improving the performance of the BAW resonator.
[0019] Optionally, the high-power capacity BAW resonator further includes a third titanium-tungsten alloy layer, and two sides of the third titanium-tungsten alloy layer are respectively connected to a side of the bottom electrode away from the piezoelectric layer and the substrate.
[0020] Optionally, the atomic mass percentage of tungsten in the first titanium-tungsten alloy layer is greater than the atomic mass percentage of titanium.
[0021] This technical solution can make the first titanium-tungsten alloy layer have a higher density and make the longitudinal wave sound velocity of the first titanium-tungsten alloy layer close to the sound velocity of the top electrode by making the tungsten atomic mass percentage in the first titanium-tungsten alloy layer greater than the titanium atomic mass percentage. Therefore, this technical solution can effectively increase the parallel resonant impedance of the bulk acoustic wave resonator and improve the power resistance of the bulk acoustic wave resonator, thereby effectively improving the performance of the bulk acoustic wave resonator.
[0022] In a second aspect, the present application further provides a method for preparing a high-power capacity BAW resonator, which is used to prepare the high-power capacity BAW resonator provided in the first aspect above. The method for preparing a high-power capacity BAW resonator comprises the following steps:
[0023] S1, forming an acoustic reflector, a bottom electrode, a piezoelectric layer and a top electrode on a substrate;
[0024] S2, forming a patterned photoresist layer on the top electrode;
[0025] S3. Growing a titanium-tungsten alloy on the top electrode based on the patterned photoresist layer, and removing the patterned photoresist layer to form a functional layer on the top electrode.
[0026] The present application provides a method for preparing a high-power capacity bulk acoustic wave resonator, in which a first titanium-tungsten alloy layer is arranged on a top electrode. Since the titanium-tungsten alloy has the advantages of good thermal stability, high hardness, high density and low atomic mobility, the present application can utilize the good thermal stability, hardness and density of the first titanium-tungsten alloy layer to block the migration and diffusion of metal atoms of the top electrode at high temperature. Therefore, the present application can utilize the first titanium-tungsten alloy layer to effectively improve the power resistance of the bulk acoustic wave resonator, thereby effectively improving the power capacity of the bulk acoustic wave resonator, so that the bulk acoustic wave resonator meets the demand for high power capacity. The first titanium-tungsten alloy layer can be used to effectively improve the power capacity of the BAW resonator, that is, the present application can set the top electrode to have a small electrode thickness and a small electrode area so that the BAW resonator can meet the requirements of high operating frequency. Therefore, the present application can simultaneously improve the working efficiency and power capacity of the BAW resonator, thereby effectively solving the problem that the working frequency of the BAW resonator and the power capacity of the BAW resonator cannot be simultaneously improved because the working frequency of the BAW resonator is negatively correlated with the electrode thickness and electrode area of the BAW resonator, and the power capacity of the BAW resonator is positively correlated with the electrode thickness and electrode area of the BAW resonator.
[0027] From the above, it can be seen that the present application provides a high-power capacity BAW resonator and a preparation method thereof, in which a first titanium-tungsten alloy layer is arranged on the top electrode. Since the titanium-tungsten alloy has the advantages of good thermal stability, high hardness, high density and low atomic mobility, the present application can utilize the good thermal stability, hardness and density of the first titanium-tungsten alloy layer to block the migration and diffusion of metal atoms of the top electrode at high temperature. Therefore, the present application can utilize the first titanium-tungsten alloy layer to effectively improve the power resistance of the BAW resonator, thereby effectively improving the power capacity of the BAW resonator, so that the BAW resonator meets the demand for high power capacity, and due to The present application can utilize the first titanium-tungsten alloy layer to effectively improve the power capacity of the BAW resonator, that is, the present application can set the top electrode to have a small electrode thickness and a small electrode area so that the BAW resonator can meet the requirements of high operating frequency. Therefore, the present application can simultaneously improve the working efficiency and power capacity of the BAW resonator, thereby effectively solving the problem that the operating frequency and power capacity of the BAW resonator cannot be simultaneously improved because the operating frequency of the BAW resonator is negatively correlated with the electrode thickness and electrode area of the BAW resonator, and the power capacity of the BAW resonator is positively correlated with the electrode thickness and electrode area of the BAW resonator. BRIEF DESCRIPTION OF THE DRAWINGS
[0028] Figure 1 A schematic cross-sectional structure diagram of a high-power capacity bulk acoustic wave resonator provided in the first embodiment of the present application.
[0029] Figure 2 A schematic cross-sectional structure diagram of a high-power capacity bulk acoustic wave resonator provided in the second embodiment of the present application.
[0030] Figure 3 A schematic cross-sectional structure diagram of a high-power capacity bulk acoustic wave resonator provided in the third embodiment of the present application.
[0031] Figure 4 A schematic cross-sectional structure diagram of a high-power capacity bulk acoustic wave resonator provided in the fourth embodiment of the present application.
[0032] Figure 5 A schematic cross-sectional structure diagram of a high-power capacity bulk acoustic wave resonator provided in the fifth embodiment of the present application.
[0033] Figure 6 A schematic cross-sectional structure diagram of a high-power capacity bulk acoustic wave resonator provided in the sixth embodiment of the present application.
[0034] Figure 7 A flow chart of a method for preparing a high-power capacity bulk acoustic wave resonator provided in an embodiment of the present application.
[0035] Figure 8A schematic diagram of a method for preparing a high-power capacity bulk acoustic wave resonator provided in an embodiment of the present application.
[0036] Figure numerals: 1. substrate; 2. bottom electrode; 3. piezoelectric layer; 4. top electrode; 5. acoustic reflector; 6. first titanium-tungsten alloy layer; 7. second titanium-tungsten alloy layer; 8. first conductive metal layer; 9. second conductive metal layer; 10. passivation layer; 11. third titanium-tungsten alloy layer; 12. sacrificial layer; 13. patterned photoresist layer. DETAILED DESCRIPTION
[0037] The technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all of the embodiments. The components of the embodiments of the present application described and shown in the drawings here can be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present application provided in the drawings is not intended to limit the scope of the application claimed for protection, but merely represents the selected embodiments of the present application. Based on the embodiments of the present application, all other embodiments obtained by those skilled in the art without making creative work belong to the scope of protection of the present application.
[0038] It should be noted that similar reference numerals and letters represent similar items in the following drawings, so once an item is defined in one drawing, it does not need to be further defined and explained in subsequent drawings. At the same time, in the description of this application, the terms "first", "second", etc. are only used to distinguish the description and cannot be understood as indicating or implying relative importance.
[0039] First, as Figure 1-Figure 6 As shown, the present application provides a high-power capacity bulk acoustic wave resonator, which includes:
[0040] A substrate 1, a bottom electrode 2, a piezoelectric layer 3, a top electrode 4 and a functional layer are connected in sequence from bottom to top, and an acoustic reflector 5 is provided on the substrate 1;
[0041] The functional layer comprises a first titanium-tungsten alloy layer 6;
[0042] The outer boundary of the projection of the first titanium-tungsten alloy layer 6 in the top view direction is located within the outer boundary of the projection of the top electrode 4 in the top view direction, and the distance between the outer boundary of the projection of the first titanium-tungsten alloy layer 6 in the top view direction and the outer boundary of the projection of the top electrode 4 in the top view direction is greater than 0.
[0043] Among them, the material of the substrate 1 of this embodiment is preferably silicon material, the material of the bottom electrode 2 and the top electrode 4 of this embodiment is preferably a metal material with high electrical conductivity, large acoustic impedance and large Young's modulus (such as any one or more of gold, molybdenum, ruthenium and platinum), the material of the bottom electrode 2 of this embodiment is preferably the same as the material of the top electrode 4 of this embodiment, and the material of the piezoelectric layer 3 of this embodiment is preferably aluminum nitride. Specifically, when the top electrode 4 and the bottom electrode 2 are externally connected to a signal source (equivalent to applying a voltage signal or an electrical signal to the top electrode 4 and the bottom electrode 2), an electric field is formed at both ends of the piezoelectric layer 3 to excite bulk acoustic waves (equivalent to exciting the piezoelectric layer 3 to generate longitudinal waves), thereby realizing the mutual conversion of electrical energy and mechanical energy and the frequency selection of the bulk acoustic wave resonator. An acoustic reflector 5 is provided on the substrate 1 of this embodiment, and the acoustic reflector 5 can be an air cavity or several layers of Bragg reflection layers, each of which is composed of a low acoustic impedance layer and a high acoustic impedance layer. In this embodiment, the substrate 1 can be etched first to form a groove on the substrate 1, and then several layers of Bragg reflection layers are formed in the groove based on the existing Bragg reflection layer formation process. It should be understood that if the acoustic reflector 5 is an air cavity, the bulk acoustic wave resonator of this embodiment is essentially a film bulk acoustic wave resonator (Film Bulk Acoustic Resonator, FBAR), and if the acoustic reflector 5 is a Bragg reflection layer, the bulk acoustic wave resonator of this embodiment is essentially a solid mounted resonator (Solid Mounted Resonator, SMR). The functional layer of this embodiment includes a first titanium-tungsten alloy layer 6, which is connected to the side of the top electrode 4 away from the piezoelectric layer 3, and the outer boundary of the projection of the first titanium-tungsten alloy layer 6 in the top view direction is located within the outer boundary of the projection of the top electrode 4 in the top view direction, and the distance between the outer boundary of the projection of the first titanium-tungsten alloy layer 6 in the top view direction and the outer boundary of the projection of the top electrode 4 in the top view direction (this distance is the minimum distance between the two outer boundaries) is greater than 0, that is, the first titanium-tungsten alloy layer 6 of this embodiment is retracted into the top electrode 4 in the top view direction.
[0044] The present application provides a high-power capacity BAW resonator, in which a first titanium-tungsten alloy layer 6 is arranged on a top electrode 4. Since the titanium-tungsten alloy has the advantages of good thermal stability, high hardness, high density and low atomic mobility, the present application can utilize the good thermal stability, hardness and density of the first titanium-tungsten alloy layer 6 to block the migration and diffusion of metal atoms of the top electrode 4 at high temperature. Therefore, the present application can utilize the first titanium-tungsten alloy layer 6 to effectively improve the power resistance of the BAW resonator, thereby effectively improving the power capacity of the BAW resonator, so that the BAW resonator meets the demand for high power capacity. The first titanium-tungsten alloy layer 6 can be used to effectively improve the power capacity of the BAW resonator, that is, the present application can set the top electrode 4 to have a small electrode thickness and a small electrode area so that the BAW resonator can meet the requirements of high operating frequency. Therefore, the present application can simultaneously improve the working efficiency and power capacity of the BAW resonator, thereby effectively solving the problem that the working frequency of the BAW resonator is negatively correlated with the electrode thickness and electrode area of the BAW resonator, and the power capacity of the BAW resonator is positively correlated with the electrode thickness and electrode area of the BAW resonator, resulting in the inability to simultaneously improve the working frequency and power capacity of the BAW resonator.
[0045] In some preferred embodiments, the outer boundary of the projection of the top electrode 4 in the top view direction does not exceed the outer boundary of the projection of the acoustic reflector 5 in the top view direction (refer to Figure 1 ). This embodiment is applicable to the case where the top electrode 4 is not externally connected. Since the outer boundary of the projection of the top electrode 4 in the top-view direction of this embodiment does not exceed the outer boundary of the projection of the acoustic reflector 5 in the top-view direction, this embodiment can effectively avoid the problem of noise generation and degradation of the performance of the BAW resonator due to the outer boundary of the projection of the top electrode 4 in the top-view direction exceeding the outer boundary of the projection of the acoustic reflector 5 in the top-view direction.
[0046] In some preferred embodiments, the portion of the top electrode 4 located outside the first titanium-tungsten alloy layer 6 has a protrusion protruding upward (refer to Figure 2-Figure 6 ), the height of the protrusion is the same as the height of the first titanium-tungsten alloy layer 6. This embodiment is equivalent to forming a groove on the top electrode 4 by using the functional layer and the protrusion.
[0047] In some preferred embodiments, one side of the top electrode 4 extends to the outside of the acoustic reflector 5, and the functional layer further includes a second titanium-tungsten alloy layer 7, which is located outside the first titanium-tungsten alloy layer 6 and extends along one side of the top electrode 4 to the outside of the acoustic reflector 5 (refer to Figure 2-Figure 6). This embodiment is applicable to the case where the top electrode 4 is externally connected, and there is a cavity between the top electrode 4 extending outside the acoustic reflector 5 and the piezoelectric layer 3, and the top electrode 4 located outside the cavity has a depression that is concave downward. Since the second titanium-tungsten alloy layer 7 of this embodiment extends outside the acoustic reflector 5 along one side of the top electrode 4, this embodiment is equivalent to increasing the cross-sectional area of the external circuit of the BAW resonator, thereby effectively reducing the resistance of the external circuit of the BAW resonator, and further effectively reducing the circuit loss of the external circuit of the BAW resonator.
[0048] In some preferred embodiments, the spacing between the first titanium-tungsten alloy layer 6 and the second titanium-tungsten alloy layer 7 is a first spacing, the spacing between the first titanium-tungsten alloy layer 6 and the top electrode 4 is a second spacing, and the first spacing and the second spacing are both within 0.5-5 μm. The first spacing of this embodiment may be the same as the second spacing, and the second spacing of this embodiment may also be different from the second spacing. Specifically, the first spacing of this embodiment is the minimum spacing between the outer boundary of the projection of the first titanium-tungsten alloy layer 6 in the top-view direction and the inner boundary of the projection of the second titanium-tungsten alloy layer 7 in the top-view direction. When the first spacing is the same as the second spacing, the first titanium-tungsten alloy layer 6 is located in the middle of the top electrode 4 that does not extend outside the acoustic reflector 5, and the boundary of the projection of the second titanium-tungsten alloy layer 7 in the top-view direction coincides with the boundary of the projection of the top electrode 4 extending outside the acoustic reflector 5 in the top-view direction. The first spacing of this embodiment is preferably the same as the second spacing, and the first spacing and the second spacing are both within a range of 0.5-5 μm. This embodiment can adjust the first spacing and the second spacing so that the acoustic impedance of the active region of the BAW resonator located in the first titanium-tungsten alloy layer 6 is greater than the acoustic impedance of the active region of the BAW resonator located outside the first titanium-tungsten alloy layer 6, so that the active region of the BAW resonator located in the first titanium-tungsten alloy layer 6 has the function of suppressing noise at the series resonance frequency, thereby effectively improving the electrical performance of the BAW resonator.
[0049] In some preferred embodiments, Figure 3As shown, the functional layer also includes a plurality of first conductive metal layers 8 and a plurality of second conductive metal layers 9. The first conductive metal layer 8 is arranged on the first titanium-tungsten alloy layer 6. The outer boundary of the projection of the first conductive metal layer 8 in the top-view direction is located within the outer boundary of the projection of the first titanium-tungsten alloy layer 6 in the top-view direction. The second conductive metal layer 9 is arranged on the second titanium-tungsten alloy layer 7. The outer boundary of the projection of the second conductive metal layer 9 in the top-view direction is located within the outer boundary of the projection of the second titanium-tungsten alloy layer 7 in the top-view direction. The functional layer of this embodiment also includes a plurality of first conductive metal layers 8 and a plurality of second conductive metal layers 9. The number of the first conductive metal layers 8 is preferably the same as the number of the second conductive metal layers 9. The materials of the first conductive metal layers 8 and the second conductive metal layers 9 of this embodiment are both materials with high electrical conductivity. This embodiment is equivalent to increasing the electrical conductivity of the functional layer by arranging the first conductive metal layer 8 on the first titanium-tungsten alloy layer 6 and the second conductive metal layer 9 on the second titanium-tungsten alloy layer 7, thereby effectively reducing the circuit loss of the functional layer.
[0050] In some preferred embodiments, the conductivity of the first conductive metal layer 8 is greater than the conductivity of the first titanium-tungsten alloy layer 6 and the top electrode 4 , and the conductivity of the second conductive metal layer 9 is greater than the conductivity of the second titanium-tungsten alloy layer 7 and the top electrode 4 .
[0051] In some preferred embodiments, Figure 2-Figure 6 As shown, the high-power capacity BAW resonator further includes a passivation layer 10, which is disposed on the functional layer. The passivation layer 10 of this embodiment can protect the functional layer, the top electrode 4, the piezoelectric layer 3 and the bottom electrode 2, so this embodiment can effectively prevent the functional layer, the top electrode 4, the piezoelectric layer 3 and the bottom electrode 2 from being corroded by the external environment or subsequent processing, thereby effectively improving the service life of the high-power capacity BAW resonator. Since the outer boundary of the projection of the first conductive metal layer 8 in the top view direction of this embodiment is located within the outer boundary of the projection of the first titanium tungsten alloy layer 6 in the top view direction, and the outer boundary of the projection of the second conductive metal layer 9 in the top view direction is located at the outer boundary of the projection of the second titanium tungsten alloy layer 7 in the top view direction, that is, the passivation layer 10 can contact a partial area of the top surface of the first titanium tungsten alloy layer 6 and a partial area of the top surface of the second titanium tungsten alloy layer 7, and titanium tungsten alloy has good adhesion to both metal electrodes and dielectric materials. Therefore, this embodiment can effectively avoid the situation where the passivation layer 10 falls off in subsequent processing or a gap is generated between the passivation layer 10 and the top electrode 4 due to insufficient adhesion of the passivation layer 10 on the top electrode 4, thereby effectively avoiding the situation where the performance of the bulk acoustic wave resonator is affected due to the fall-off of the passivation layer 10 or the gap is generated between the passivation layer 10 and the top electrode 4.
[0052] In some preferred embodiments, Figure 4As shown, the passivation layer 10 does not cover the gap between the first titanium-tungsten alloy layer 6 and the top electrode 4 (refer to Figure 4 a) and the gap between the first titanium-tungsten alloy layer 6 and the second titanium-tungsten alloy layer 7 (reference Figure 4 b in the figure). This embodiment is equivalent to increasing the depth of the groove formed on the top electrode 4 to increase the difference between the acoustic impedance of the active region of the BAW resonator located in the first titanium-tungsten alloy layer 6 and the acoustic impedance of the active region of the BAW resonator located outside the first titanium-tungsten alloy layer 6. Therefore, this embodiment can further suppress the clutter at the series resonance frequency, thereby effectively improving the performance of the BAW resonator.
[0053] In some preferred embodiments, Figure 6 As shown, the high-power capacity BAW resonator also includes a third titanium-tungsten alloy layer 11, and the two sides of the third titanium-tungsten alloy layer 11 are respectively connected to the side of the bottom electrode 2 away from the piezoelectric layer 3 and the substrate 1. The high-power capacity BAW resonator of this embodiment also includes a third titanium-tungsten alloy layer 11, and the two sides of the third titanium-tungsten alloy layer 11 are respectively connected to the side of the bottom electrode 2 away from the piezoelectric layer 3 and the substrate 1. The function of the third titanium-tungsten alloy layer 11 is the same as that of the first titanium-tungsten alloy layer 6. This embodiment is equivalent to further improving the power resistance of the BAW resonator by arranging the third titanium-tungsten alloy layer 11 between the bottom electrode 2 and the substrate 1.
[0054] In some preferred embodiments, the atomic mass percentage of tungsten in the first titanium-tungsten alloy layer 6 is greater than the atomic mass percentage of titanium. This embodiment can make the first titanium-tungsten alloy layer 6 have a higher density and make the longitudinal wave sound velocity of the first titanium-tungsten alloy layer 6 close to the sound velocity of the top electrode 4 by making the atomic mass percentage of tungsten in the first titanium-tungsten alloy layer 6 greater than the atomic mass percentage of titanium. Therefore, this embodiment can effectively increase the parallel resonant impedance of the bulk acoustic wave resonator and improve the power resistance of the bulk acoustic wave resonator, thereby effectively improving the performance of the bulk acoustic wave resonator. Preferably, the ratio of the atomic mass percentage of tungsten to the atomic mass percentage of titanium in the first titanium-tungsten alloy layer 6 of this embodiment is 9.
[0055] As can be seen from the above, the present application provides a high-power capacity BAW resonator, in which a first titanium-tungsten alloy layer 6 is arranged on the top electrode 4. Since the titanium-tungsten alloy has the advantages of good thermal stability, high hardness, high density and low atomic mobility, and the present application can use the good thermal stability, hardness and density of the first titanium-tungsten alloy layer 6 to block the migration and diffusion of metal atoms of the top electrode 4 at high temperatures, the present application can use the first titanium-tungsten alloy layer 6 to effectively improve the power resistance of the BAW resonator, thereby effectively improving the power capacity of the BAW resonator, so that the BAW resonator meets the demand for high power capacity, and since the present application Please be able to use the first titanium-tungsten alloy layer 6 to effectively improve the power capacity of the BAW resonator, that is, the present application can set the top electrode 4 to have a small electrode thickness and a small electrode area so that the BAW resonator can meet the requirements of high operating frequency. Therefore, the present application can simultaneously improve the working efficiency and power capacity of the BAW resonator, thereby effectively solving the problem that the operating frequency of the BAW resonator is negatively correlated with the electrode thickness and electrode area of the BAW resonator, and the power capacity of the BAW resonator is positively correlated with the electrode thickness and electrode area of the BAW resonator, resulting in the inability to simultaneously improve the operating frequency and power capacity of the BAW resonator.
[0056] Second, as Figure 7-Figure 8 As shown, the present application also provides a method for preparing a high-power capacity BAW resonator, which is used to prepare the high-power capacity BAW resonator provided in the first aspect above. The method for preparing the high-power capacity BAW resonator comprises the following steps:
[0057] S1, forming an acoustic reflection mirror 5, a bottom electrode 2, a piezoelectric layer 3 and a top electrode 4 on a substrate 1;
[0058] S2, forming a patterned photoresist layer 13 on the top electrode 4;
[0059] S3 . Growing a titanium-tungsten alloy on the top electrode 4 based on the patterned photoresist layer 13 , and removing the patterned photoresist layer 13 to form a functional layer on the top electrode 4 .
[0060] The embodiment of the present application provides a method for preparing a high-power capacity bulk acoustic wave resonator. The method for preparing a high-power capacity bulk acoustic wave resonator provided in the embodiment is used to prepare the high-power capacity bulk acoustic wave resonator provided in the first aspect above. The principle of the method for preparing a high-power capacity bulk acoustic wave resonator in the embodiment is the same as the principle of the high-power bulk acoustic wave resonator provided in the first aspect above, and will not be discussed in detail here. The acoustic reflector 5 of this embodiment can be an air cavity or several layers of Bragg reflector layers. Taking the reflector as a Bragg reflector layer as an example, the specific process of step S1 can be: etching the substrate 1 to form a groove on the substrate 1; forming several layers of Bragg reflector layers in the groove based on the existing Bragg reflector layer formation process; and sequentially growing the bottom electrode 2, the piezoelectric layer 3 and the top electrode 4 on the substrate 1. Step S2 can form a patterned photoresist layer 13 on the top electrode 4 based on the existing photoresist formation process, and step S3 forms a functional layer on the top electrode 4 by growing a titanium-tungsten alloy on the top electrode 4 based on the patterned photoresist layer 13.
[0061] In some preferred embodiments, the acoustic reflector 5 is an air cavity, the functional layer includes a first titanium-tungsten alloy layer 6 and a second titanium-tungsten alloy layer 7, and step S1 includes:
[0062] S11, etching the top of the substrate 1 to form a groove on the substrate 1, and forming a sacrificial layer 12 in the groove;
[0063] S12, sequentially growing a bottom electrode 2, a piezoelectric layer 3 and a top electrode 4 on the substrate 1;
[0064] Step S3 includes:
[0065] S31, growing a titanium-tungsten alloy on the top electrode 4 based on the patterned photoresist layer 13, and removing the patterned photoresist layer 13 to form a first titanium-tungsten alloy layer 6 and a second titanium-tungsten alloy layer 7 on the top electrode 4;
[0066] S32, forming a passivation layer 10 on the top electrode 4, which wraps the top surface and side surfaces of the first titanium-tungsten alloy layer 6 and the top surface of the second titanium-tungsten alloy layer 7;
[0067] Step S1 also includes the following steps performed after step S32:
[0068] S113 , using a hydrofluoric acid solution to remove the sacrificial layer 12 to form an acoustic reflector 5 on the substrate 1 .
[0069] Since the first titanium-tungsten alloy layer 6 of this embodiment is located in the active area of the high-power capacity BAW resonator, and this embodiment first forms a passivation layer 10 on the top electrode 4 to wrap the top surface and side surfaces of the first titanium-tungsten alloy layer 6 and the top surface of the second titanium-tungsten alloy layer 7, and then uses a hydrofluoric acid solution to remove the sacrificial layer 12, this embodiment can effectively avoid the first titanium-tungsten alloy layer 6 being corroded due to contact with the hydrofluoric acid solution and the first titanium-tungsten alloy layer 6 having film defects, thereby effectively avoiding the performance deterioration of the high-power capacity BAW resonator due to the presence of film defects in the titanium-tungsten alloy layer located in the active area of the high-power capacity BAW resonator. It should be understood that since the main function of the second titanium-tungsten alloy layer 7 is to increase the electrical conductivity of the external circuit of the high-power capacity BAW resonator and reduce the circuit loss of the external circuit of the high-power capacity BAW resonator, and the second titanium-tungsten alloy layer 7 is located outside the active area of the high-power capacity BAW resonator, even if there are film defects in the second titanium-tungsten alloy layer 7, the performance of the high-power capacity BAW resonator will not deteriorate. Therefore, the passivation layer 10 of this embodiment only wraps the top surface of the second titanium-tungsten alloy layer 7.
[0070] From the above, it can be seen that the present application provides a method for preparing a high-power capacity BAW resonator, in which a first titanium-tungsten alloy layer 6 is arranged on the top electrode 4. Since the titanium-tungsten alloy has the advantages of good thermal stability, high hardness, high density and low atomic mobility, the present application can use the good thermal stability, hardness and density of the first titanium-tungsten alloy layer 6 to block the migration and diffusion of metal atoms of the top electrode 4 at high temperatures. Therefore, the present application can use the first titanium-tungsten alloy layer 6 to effectively improve the power resistance of the BAW resonator, thereby effectively improving the power capacity of the BAW resonator, so that the BAW resonator meets the demand for high power capacity, and due to The present application can utilize the first titanium-tungsten alloy layer 6 to effectively improve the power capacity of the BAW resonator, that is, the present application can set the top electrode 4 to have a small electrode thickness and a small electrode area so that the BAW resonator can meet the requirements of high operating frequency. Therefore, the present application can simultaneously improve the working efficiency and power capacity of the BAW resonator, thereby effectively solving the problem that the operating frequency and power capacity of the BAW resonator cannot be simultaneously improved because the operating frequency of the BAW resonator is negatively correlated with the electrode thickness and electrode area of the BAW resonator, and the power capacity of the BAW resonator is positively correlated with the electrode thickness and electrode area of the BAW resonator.
[0071] As can be seen from the above, the present application provides a high-power capacity BAW resonator and a preparation method thereof, in which a first titanium-tungsten alloy layer 6 is arranged on the top electrode 4. Since the titanium-tungsten alloy has the advantages of good thermal stability, high hardness, high density and low atomic mobility, the present application can utilize the good thermal stability, hardness and density of the first titanium-tungsten alloy layer 6 to block the migration and diffusion of metal atoms of the top electrode 4 at high temperatures. Therefore, the present application can utilize the first titanium-tungsten alloy layer 6 to effectively improve the power resistance of the BAW resonator, thereby effectively improving the power capacity of the BAW resonator, so that the BAW resonator meets the demand for high power capacity. In the present application, the first titanium-tungsten alloy layer 6 can be used to effectively improve the power capacity of the BAW resonator, that is, the present application can set the top electrode 4 to have a small electrode thickness and a small electrode area so that the BAW resonator can meet the requirements of high operating frequency. Therefore, the present application can simultaneously improve the working efficiency and power capacity of the BAW resonator, thereby effectively solving the problem that the working frequency and power capacity of the BAW resonator cannot be simultaneously improved because the working frequency of the BAW resonator is negatively correlated with the electrode thickness and electrode area of the BAW resonator, and the power capacity of the BAW resonator is positively correlated with the electrode thickness and electrode area of the BAW resonator.
[0072] In the embodiments provided in the present application, it should be understood that, herein, relational terms such as first and second, etc. are merely used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations.
[0073] The above description is only an embodiment of the present application and is not intended to limit the protection scope of the present application. For those skilled in the art, the present application may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.
Claims
1. A high power capacity bulk acoustic wave resonator, characterized in that: The high-power capacity bulk acoustic wave resonator comprises: A substrate, a bottom electrode, a piezoelectric layer, a top electrode and a functional layer are connected in sequence from bottom to top, and an acoustic reflector is arranged on the substrate; The functional layer includes a first titanium-tungsten alloy layer; The outer boundary of the projection of the first titanium-tungsten alloy layer in the top-view direction is located within the outer boundary of the projection of the top electrode in the top-view direction, and the distance between the outer boundary of the projection of the first titanium-tungsten alloy layer in the top-view direction and the outer boundary of the projection of the top electrode in the top-view direction is greater than 0; One side of the top electrode extends to the outside of the acoustic reflector, and the functional layer further includes a second titanium-tungsten alloy layer, and the second titanium-tungsten alloy layer extends along one side of the top electrode to the outside of the acoustic reflector; The functional layer also includes a plurality of first conductive metal layers and a plurality of second conductive metal layers. The first conductive metal layer is arranged on the first titanium-tungsten alloy layer, and the outer boundary of the projection of the first conductive metal layer in the top-view direction is located within the outer boundary of the projection of the first titanium-tungsten alloy layer in the top-view direction. The second conductive metal layer is arranged on the second titanium-tungsten alloy layer, and the outer boundary of the projection of the second conductive metal layer in the top-view direction is located within the outer boundary of the projection of the second titanium-tungsten alloy layer in the top-view direction.
2. The high power capacity bulk acoustic wave resonator according to claim 1, characterized in that: The distance between the first titanium-tungsten alloy layer and the second titanium-tungsten alloy layer is a first distance, the distance between the first titanium-tungsten alloy layer and the top electrode is a second distance, and the first distance and the second distance are both within 0.5-5 μm.
3. The high power capacity bulk acoustic wave resonator according to claim 1, characterized in that: The electrical conductivity of the first conductive metal layer is greater than the electrical conductivity of the first titanium-tungsten alloy layer and the top electrode, and the electrical conductivity of the second conductive metal layer is greater than the electrical conductivity of the second titanium-tungsten alloy layer and the top electrode.
4. The high power capacity BAW resonator according to claim 1, characterized in that: The high-power BAW resonator further includes a passivation layer disposed on the functional layer.
5. The high power capacity bulk acoustic wave resonator according to claim 4, characterized in that: The passivation layer does not cover a gap between the first titanium-tungsten alloy layer and the top electrode and a gap between the first titanium-tungsten alloy layer and the second titanium-tungsten alloy layer.
6. The high power capacity bulk acoustic wave resonator according to claim 1, characterized in that: The high-power capacity BAW resonator further includes a third titanium-tungsten alloy layer, and two sides of the third titanium-tungsten alloy layer are respectively connected to a side of the bottom electrode away from the piezoelectric layer and the substrate.
7. The high power capacity BAW resonator according to claim 1, characterized in that: The atomic mass percentage of tungsten in the first titanium-tungsten alloy layer is greater than the atomic mass percentage of titanium.
8. A method for preparing a high-power capacity bulk acoustic wave resonator, characterized in that: Used to prepare the high-power capacity BAW resonator according to any one of claims 1 to 7, the high-power capacity BAW resonator preparation method comprises the following steps: S1, forming the acoustic reflector, the bottom electrode, the piezoelectric layer and the top electrode on the substrate; S2, forming a patterned photoresist layer on the top electrode; S3. Growing a titanium-tungsten alloy on the top electrode based on the patterned photoresist layer, and removing the patterned photoresist layer to form a functional layer on the top electrode.
Citation Information
Patent Citations
Single-crystal piezoelectric bulk acoustic wave resonator, filter, and electronic device
CN115250103A