Film bulk acoustic resonator and communication equipment

Abstract

The utility model discloses a film bulk acoustic resonator and a communication device, and the film bulk acoustic resonator comprises a carrier which comprises a first part and a second part; a cavity formed in the second portion of the carrier; the lower electrode comprises a first part and a second part, the first part of the lower electrode extends from the lower surface of the second part of the lower electrode to the upper surface of the second part of the carrier, and the height of the first part of the lower electrode is greater than or equal to that of the cavity; a piezoelectric layer formed on the lower electrode; and an upper electrode formed on the piezoelectric layer.

Description

Technical Field

[0001] The utility model relates to the field of communications, and in particular to a thin film bulk acoustic wave resonator and communication equipment. Background Art

[0002] As core components in RF front-ends, filters offer exceptional performance, such as low insertion loss, steep filter curves, high isolation, and compact size. These features are crucial for driving the development of next-generation communication standards and the miniaturization and multifunctionality of personal mobile devices. The latest generation of bulk acoustic wave (BAW) technology is effectively addressing both of these challenges. BAW filters fabricated using BAW technology exhibit steeper filter curves, lower insertion loss, and superior out-of-band rejection.

[0003] Film Bulk Acoustic Resonator (FBAR) plays an important role in communications, sensors and other fields due to its advantages such as small size, high frequency, large power capacity and high sensitivity. It occupies an increasingly large share in the RF front-end field, especially in the RF filter market. It also has great development advantages in the fields of biosensing and medical measurement.

[0004] The electrical energy and acoustic waves in the FBAW resonator are inevitably converted into heat energy. As the application scenarios of BAW filters increase, the applied power also gradually increases, making the self-heating of the FBAW resonator serious. Figure 1 , Figure 1 Figure 2 shows the schematic structural diagram of the thin film bulk acoustic resonator. Figure 1 As shown, a FBAR includes a substrate 101, a cavity 102 formed in the substrate 101, a lower electrode 103, an upper electrode 105, and a piezoelectric layer 104 sandwiched between the upper and lower electrodes. The piezoelectric layer 104 and the upper and lower electrodes, key components of the FBAR, are only micrometer or nanometer thick. Heat accumulation within these layers can have significant negative effects, such as causing the FBAR's temperature to rise, shifting its frequency and deteriorating its performance. Furthermore, the FBAR's effective resonance region is located within a cavity structure, and air has poor thermal conductivity. Therefore, the FBAR has a large temperature gradient in the lateral direction, resulting in two resonance peaks near the resonant frequency, affecting the filtering performance of the BAW filter. Alternatively, it can accelerate aging of the piezoelectric layer 104 or directly damage it, thereby impacting the reliability and lifespan of the FBAR. Utility Model Content

[0005] In response to the above technical problems, the utility model designs a resonator structure that can improve power capacity.

[0006] The following is a brief overview of the present invention to provide a basic understanding of certain aspects of the present invention. It should be understood that this overview is not an exhaustive overview of the present invention. It is not intended to identify key or important aspects of the present invention, nor is it intended to limit the scope of the present invention. Its purpose is simply to present certain concepts in a simplified form as a prelude to the more detailed description discussed later.

[0007] According to one aspect of the present invention, a thin film bulk acoustic resonator is provided, comprising: a carrier, the carrier comprising a first part and a second part; a cavity, the cavity being formed in the second part of the carrier; a lower electrode, the lower electrode comprising a first part and a second part, the first part of the lower electrode extending from the lower surface of the second part of the lower electrode to the upper surface of the second part of the carrier, the height of the first part of the lower electrode being greater than or equal to the height of the cavity; a piezoelectric layer formed on the lower electrode; and an upper electrode formed on the piezoelectric layer.

[0008] Furthermore, the cross section of the first portion of the lower electrode is annular, and the longitudinal section is formed into an inverted π shape or an inverted X shape.

[0009] Furthermore, the first portion of the lower electrode is a single substructure.

[0010] Furthermore, the first portion of the lower electrode is arranged at the center of the second portion of the lower electrode.

[0011] Furthermore, the first portion of the lower electrode includes a plurality of substructures.

[0012] Furthermore, the substructures of the first portion of the lower electrode are arranged in the middle region of the second portion of the lower electrode and are symmetrically arranged relative to the center of the second portion of the lower electrode.

[0013] Furthermore, the width of the upper surface of the substructure is greater than the width of the lower surface of each substructure.

[0014] Furthermore, the first part and the second part of the lower electrode are a multi-layer or single-layer structure.

[0015] Furthermore, the thermal conductivity of the first portion of the lower electrode is greater than the thermal conductivity of the second portion of the lower electrode.

[0016] According to another aspect of the present invention, a communication device is provided, characterized in that it includes the above-mentioned thin film bulk acoustic resonator.

[0017] This solution can at least achieve the following technical benefits: without changing the area, it effectively conducts heat from the center of the resonator to the substrate via the thermally conductive structure, lowering the overall resonator temperature. This reduces frequency shift and performance degradation caused by high temperatures, thereby improving the device's power capacity. Furthermore, it increases the electrode transmission path, reducing ohmic losses, fundamentally reducing heat generation, and making the device structure more stable. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The following description of the present invention will provide a more comprehensive understanding of the above and other purposes, features, and advantages of the present invention, with reference to the accompanying drawings. The accompanying drawings are intended only to illustrate the principles of the present invention. The sizes and relative positions of elements in the drawings are not necessarily drawn to scale.

[0019] Figure 1 A schematic diagram showing the structure of a resonator in the prior art is shown;

[0020] Figure 2 A schematic structural diagram of a thin film bulk acoustic resonator provided by the present invention is shown;

[0021] Figure 3 Show Figure 2 Variations of the provided thin film bulk acoustic resonator;

[0022] Figure 4 Show Figure 2-Figure 3 A top view of a thin film bulk acoustic resonator is provided;

[0023] Figure 5 A schematic structural diagram of another thin film bulk acoustic resonator provided by the present disclosure is shown;

[0024] Figure 6a Show Figure 1 The temperature simulation diagram of the thin film bulk acoustic resonator is provided;

[0025] Figure 6b A temperature simulation diagram of the thin film bulk acoustic resonator provided by the present invention is shown. DETAILED DESCRIPTION

[0026] The following describes exemplary embodiments of the present invention in conjunction with the accompanying drawings. For the sake of clarity and conciseness, not all features that implement the present invention are described in this specification. However, it should be understood that in developing any such implementation of the present invention, many decisions specific to the invention may be made to achieve the developer's specific goals, and these decisions may vary from one invention to another.

[0027] It should also be noted here that, in order to avoid obscuring the present invention due to unnecessary details, the accompanying drawings only show device structures closely related to the solutions according to the present invention, while other details that are not closely related to the present invention are omitted.

[0028] It should be understood that the present invention is not limited to the described embodiments as described below with reference to the accompanying drawings. Herein, features between different embodiments may be interchanged or borrowed, and one or more features may be omitted from one embodiment, where feasible. It should be understood that the manufacturing steps of the present invention are illustrative in the examples, and the order of the steps is adjustable.

[0029] First embodiment

[0030] Figure 2 FIG2 shows a schematic structural diagram of a thin film bulk acoustic resonator provided by the present invention, wherein the same reference numerals represent the same components.

[0031] like Figure 2 As shown, the thin film bulk acoustic wave resonator includes: a carrier 1000, in which a cavity 1100 is formed. It is understood by those skilled in the art that the carrier 1000 can be exemplarily composed of a substrate, and the substrate can be, for example, silicon (Si), gallium arsenide (GaAs), indium phosphide (InP), glass, sapphire, aluminum oxide, or the like. 、 Alternatively, carrier 1000 may be made of a composite material such as SiC that is compatible with semiconductor processes. Alternatively, carrier 1000 may be formed of a substrate with a dielectric layer formed thereon. The dielectric layer may be a single layer or multiple layers, and the dielectric layer may be made of, for example, silicon dioxide (SiO2), silicon nitride (Si3N4), silicon dioxide / silicon nitride / silicon dioxide (ONO), aluminum oxide (Al2O3), or the like. Carrier 1000 includes a first portion and a second portion.

[0032] Furthermore, the cavity 1100 can be formed in the second portion of the carrier 1000 by etching away a portion of the carrier 1000. When the carrier 1000 is a composite component, the cavity 1100 can be formed in the substrate, in the dielectric layer, or in both the substrate and the dielectric layer. The upper surface of the second portion of the carrier 1000 is lower than the upper surface of the first portion of the carrier 1000.

[0033] A lower electrode 2000 is formed on the carrier 1000, completely covering the cavity 1100. The lower electrode 2000 includes a first portion and a second portion. The first portion of the lower electrode 2000 includes a single structure extending from the lower surface of the second portion of the lower electrode 2000 to the upper surface of the second portion of the carrier 1000. Exemplarily, the single structure of the first portion of the lower electrode 2000 is disposed within the cavity 1100, and has a circular cross-section and an inverted π-shaped or inverted ∠-shaped longitudinal section. The upper surface of the first portion of the lower electrode 2000 is connected to the first portion of the lower surface of the second portion of the lower electrode 2000. The lower surface of the first portion of the lower electrode 2000 is connected to the upper surface of the second portion of the carrier 1000. The second portion of the lower surface of the second portion of the lower electrode 2000 is connected to the upper surface of the first portion of the carrier 1000. The height of the first portion of the lower electrode 2000 is equal to the height of the cavity 1100. It is understood that the connection between the lower surface of each portion of the lower electrode 2000 and the upper surface of the carrier 1000 may be a direct connection or an indirect connection via a seed layer.

[0034] The first portion and the second portion of the lower electrode 2000 can both be a single layer or multiple layers, and the lower electrode 2000 can be formed of one or more conductive materials, such as various metals compatible with semiconductor processes, including copper (Cu), tungsten (W), molybdenum (Mo), iridium (Ir), aluminum (Al), platinum (Pt), ruthenium (Ru), niobium (Nb) or hafnium (Hf). It is understandable that the electrode materials of the first portion of the lower electrode 2000 and the second portion of the lower electrode 2000 may also be inconsistent. Preferably, the material of the first portion of the lower electrode 2000 is a metal with a large electrical conductivity and thermal conductivity, such as copper (Cu), aluminum (Al) and tungsten (W).

[0035] Furthermore, because heat in the FBAR is primarily concentrated at its center, the first portion of the lower electrode 2000 is preferably formed at the center of the second portion of the lower electrode 2000, with the width of the upper surface of the first portion of the lower electrode 2000 being slightly greater than the width of the lower surface of the first portion. This structural arrangement allows the first portion of the lower electrode 2000 to provide better support, making the structure more stable. Furthermore, the first portion of the lower electrode 2000, located at the center of the second portion of the lower electrode 2000, conducts heat from the center of the FBAR to the substrate as much as possible, reducing the impact of self-heating on the performance of the FBAR. Furthermore, the increased metal path reduces ohmic losses and heat generation.

[0036] See also Figure 3 , Figure 3 Show Figure 2 A modified example of a thin film bulk acoustic resonator is provided, wherein the same reference numerals represent the same components. Figure 3 As shown, the height of the first portion of the lower electrode 2000 is greater than the height of the cavity 1100, that is, the lower surface of the first portion of the lower electrode 2000 is lower than the upper surface of the second portion of the carrier 1000. This arrangement can increase the heat conduction area and better dissipate heat.

[0037] A piezoelectric layer 3000 is formed on the lower electrode 2000 . The piezoelectric layer 3000 may be formed of any piezoelectric material compatible with semiconductor processes, such as aluminum nitride (AlN), doped aluminum nitride, or zirconate titanate (PZT).

[0038] An upper electrode 4000 is formed on the piezoelectric layer 3000. The upper electrode 4000 can be formed from one or more conductive materials, such as tungsten, molybdenum, iridium, aluminum, platinum, ruthenium, niobium, or hafnium, which are compatible with semiconductor processes. The upper electrode 4000 can be made of the same material as or different from the lower electrode 2000. A passivation layer 5000 can also be formed on the upper electrode 4000.

[0039] See also Figure 4 , Figure 4 Show Figure 2-Figure 3 A top view of a thin film bulk acoustic resonator is provided, wherein the same reference numerals denote the same components. The upper electrode 4000 and the lower electrode 2000 may be formed in a circle, a regular pentagon, or a polygon with an inner angle greater than 90 degrees.

[0040] Second embodiment

[0041] The second embodiment differs from the first embodiment only in the arrangement of the lower electrode 2000 , and other parts are the same as those in the first embodiment, which will not be described again.

[0042] See also Figure 5 , Figure 5 A schematic structural diagram of the thin film bulk acoustic resonator provided by the present disclosure is shown.

[0043] A lower electrode 2000 is formed on the carrier 1000 to completely cover the cavity 1100. The lower electrode 2000 includes a first portion and a second portion. The first portion of the lower electrode 2000 includes a plurality of substructures extending from the second portion toward the upper surface of the second portion of the carrier 1000. Exemplarily, the first portion of the lower electrode 2000 is disposed within the cavity 1100 and includes at least two substructures whose cross sections are formed in the shape of an inverted π or an inverted ∠ shape. The upper surface of the first portion of the lower electrode 2000 is connected to the first portion of the lower surface of the second portion of the lower electrode 2000. The lower surface of the first portion of the lower electrode 2000 is connected to the upper surface of the second portion of the carrier 1000. The height of the first portion of the lower electrode 2000 is equal to the height of the cavity 1100, and the second portion of the lower surface of the second portion of the lower electrode 2000 is connected to the upper surface of the first portion of the carrier 1000. It is understood that the connection between the lower surface of each portion of the lower electrode 2000 and the upper surface of the carrier 1000 may be a direct connection or an indirect connection via a seed layer.

[0044] The first portion and the second portion of the lower electrode 2000 can both be a single layer or multiple layers, and the lower electrode 2000 can be formed of one or more conductive materials, such as various metals compatible with semiconductor processes, including copper (Cu), tungsten (W), molybdenum (Mo), iridium (Ir), aluminum (Al), platinum (Pt), ruthenium (Ru), niobium (Nb) or hafnium (Hf). It is understandable that the electrode materials of the first portion of the lower electrode 2000 and the second portion of the lower electrode 2000 may also be inconsistent. Preferably, the material of the first portion of the lower electrode 2000 is a metal with a large electrical conductivity and thermal conductivity, such as copper (Cu), aluminum (Al) and tungsten (W).

[0045] Furthermore, since the heat of the thin film bulk acoustic wave resonator is mainly concentrated in the center, the substructure of the first part of the lower electrode 2000 is formed in the middle area of the second part of the lower electrode 2000. Preferably, the substructure of the first part of the lower electrode 2000 is symmetrically arranged relative to the center of the second part of the lower electrode 2000. Furthermore, the width of the upper surface of each substructure in the first part of the lower electrode 2000 is slightly larger than the width of the lower surface of each substructure in the first part. By setting up such a structure, the first part of the lower electrode 2000 can play a better supporting role, making the structure more stable. At the same time, through the first part of the lower electrode 2000 set at the center, the heat in the center of the thin film bulk acoustic wave resonator is conducted to the substrate as much as possible, reducing the influence of self-heating effect on the performance of the thin film bulk acoustic wave resonator. At the same time, the increased metal path reduces the ohmic loss and also reduces heat generation.

[0046] In a variation of this embodiment, the height of each substructure of the first portion of the lower electrode 2000 is greater than the height of the cavity 1100, that is, the lower surface of each substructure of the first portion of the lower electrode 2000 is lower than the upper surface of the second portion of the carrier 1000. This arrangement increases the heat conduction area and improves heat dissipation.

[0047] See also Figure 6a-6b , Figure 6b A temperature simulation diagram of the thin film bulk acoustic resonator provided by the present invention is shown. Figure 6a Show Figure 1 A temperature simulation plot of a thin film bulk acoustic resonator is provided.

[0048] contrast Figure 6a and Figure 6b It can be seen that the thin film bulk acoustic resonator provided by the utility model is Figure 1 Compared with the thin film bulk acoustic wave resonator provided by the present invention, under the same heating conditions, due to the arrangement of the first part of the lower electrode, the temperature of the thin film bulk acoustic wave resonator provided by the present invention is lower in a steady state, that is, the heat conduction effect is better.

[0049] The thin film bulk acoustic wave resonator provided by the present invention can effectively conduct the heat in the center of the thin film bulk acoustic wave resonator to the substrate through the heat conduction structure without changing the area, thereby reducing the overall temperature of the thin film bulk acoustic wave resonator, thereby reducing the frequency offset and performance deterioration caused by high temperature, and thus improving the power capacity of the device. At the same time, the electrode transmission path is increased, the ohmic loss is reduced, and the heat generation is reduced from the root. The metal structure can also play a good supporting role, making the device structure more stable. Compared with the traditional method of splitting the resonator with a larger dissipation density to increase its area and reduce the dissipation power density when increasing the power capacity, it is more conducive to the miniaturization of the device.

[0050] The thin film bulk acoustic wave resonator prepared using the carrier in the present invention can be used to form a bulk acoustic wave filter. The bulk acoustic wave filter can be used in the field of portable communication devices such as mobile phones, personal digital assistants (PDAs), personal wearable devices, and electronic game devices. The bulk acoustic wave filter can include any one of the bulk acoustic wave resonators in the present invention.

[0051] The present invention has been described above with reference to specific embodiments. However, those skilled in the art should understand that these descriptions are merely illustrative and do not limit the scope of protection of the present invention. Those skilled in the art may make various variations and modifications to the present invention based on the spirit and principles of the present invention, and such variations and modifications are also within the scope of the present invention.

Claims

1. A thin film bulk acoustic resonator, characterized in that: include: a carrier comprising a first portion and a second portion; a cavity formed in the second portion of the carrier; a lower electrode, the lower electrode comprising a first portion and a second portion, the first portion of the lower electrode extending from a lower surface of the second portion of the lower electrode to an upper surface of the second portion of the carrier, and a height of the first portion of the lower electrode being greater than or equal to a height of the cavity; a piezoelectric layer formed on the lower electrode; An upper electrode is formed on the piezoelectric layer.

2. The thin film bulk acoustic resonator according to claim 1, wherein: The cross section of the first portion of the lower electrode is annular, and the longitudinal section is formed into an inverted π shape or an inverted X shape.

3. The thin film bulk acoustic resonator according to claim 1 or 2, wherein: The first portion of the lower electrode is a single substructure.

4. The thin film bulk acoustic resonator according to claim 3, wherein: The first portion of the lower electrode is disposed at a center of the second portion of the lower electrode.

5. The thin film bulk acoustic resonator according to claim 1 or 2, wherein: The first portion of the lower electrode includes a plurality of substructures.

6. The thin film bulk acoustic resonator according to claim 5, wherein: The substructures of the first portion of the lower electrode are arranged in the middle region of the second portion of the lower electrode and are symmetrically arranged relative to the center of the second portion of the lower electrode.

7. The thin film bulk acoustic resonator according to claim 6, wherein: The width of the upper surface of the substructure is greater than the width of the lower surface of each substructure.

8. The thin film bulk acoustic resonator according to claim 7, wherein: The first portion and the second portion of the lower electrode are multi-layer or single-layer structures.

9. The thin film bulk acoustic resonator according to claim 8, characterized in that :The thermal conductivity of the first portion of the lower electrode is greater than the thermal conductivity of the second portion of the lower electrode.

10. A communication device, characterized in that: The thin film bulk acoustic resonator comprises the thin film bulk acoustic resonator according to any one of claims 1 to 9.

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