Bulk acoustic wave resonator, method of manufacturing bulk acoustic wave resonator, bulk acoustic wave filter, and in-vehicle device

Abstract

The application relates to the technical field of semiconductors, for example to a bulk acoustic wave resonator and a manufacturing method thereof, a bulk acoustic wave filter and a vehicle-mounted device. The bulk acoustic wave resonator comprises a carrier substrate, a piezoelectric resonant structure arranged on the carrier substrate, the piezoelectric resonant structure comprising a bottom electrode, a piezoelectric layer and a top electrode which are sequentially arranged on the carrier substrate, and a temperature compensation layer arranged in the piezoelectric resonant structure, wherein the temperature compensation layer is a patterned structure comprising a plurality of discrete patterns. The temperature compensation material of the present application is discontinuous in the plane and is divided into a plurality of mutually separated units or patterns, thereby compensating for the frequency temperature drift inherent in the piezoelectric material itself, reducing the frequency temperature coefficient of the resonator and improving the frequency stability thereof under different ambient temperatures. While obtaining temperature compensation, the problems of serious degradation of the quality factor and substantial increase of the insertion loss caused by the traditional continuous temperature compensation layer are avoided.

Description

Technical Field

[0001] This application relates to the field of semiconductor technology, such as a bulk acoustic wave resonator and its manufacturing method, a bulk acoustic wave filter, and an in-vehicle device. Background Technology

[0002] Thin-film bulk acoustic wave resonators (BAS) are core filtering components in modern radio frequency (RF) front-end modules, and their performance directly determines the signal quality of communication systems. However, the piezoelectric materials used in traditional BAS resonators have a negative temperature coefficient, causing their resonant frequency to drift with changes in ambient temperature. This frequency drift degrades the passband characteristics of the filter, especially under harsh operating conditions of high temperature and high power, such as in automotive environments and base station applications, severely affecting the stability and reliability of the system.

[0003] In related technologies, to improve temperature stability, a continuous temperature compensation layer consisting of a material with a positive temperature coefficient, such as silicon dioxide, is inserted into the acoustic path of the resonator to compensate for the frequency temperature coefficient. However, while the continuous temperature compensation layer can compensate for frequency drift, the severe acoustic impedance mismatch between it and the upper and lower layers leads to strong acoustic wave scattering and interface losses, significantly degrading the resonator's quality factor (Q value). This results in performance degradation problems such as increased filter insertion loss and worsened out-of-band rejection.

[0004] It should be noted that the information disclosed in the background section above is only used to enhance the understanding of the background of this application, and therefore may include information that does not constitute prior art known to those skilled in the art. Summary of the Invention

[0005] To provide a basic understanding of some aspects of the disclosed embodiments, a brief summary is given below. This summary is not intended as a general commentary, nor is it intended to identify key / important components or describe the scope of protection of these embodiments, but rather as a prelude to the detailed description that follows.

[0006] This disclosure provides a bulk acoustic wave resonator and its manufacturing method, a bulk acoustic wave filter, and an automotive device to shorten the production cycle of device packaging.

[0007] In some embodiments, a bulk acoustic wave resonator is provided, comprising: a carrier substrate; a piezoelectric resonant structure disposed on the carrier substrate, the piezoelectric resonant structure comprising a bottom electrode, a piezoelectric layer and a top electrode sequentially stacked on the carrier substrate; and a temperature compensation layer disposed within the piezoelectric resonant structure; wherein the temperature compensation layer is a patterned structure comprising multiple discrete patterns.

[0008] Optionally, multiple discrete patterns are arranged in an array within the effective region of the piezoelectric resonant structure.

[0009] Optionally, the discrete figures may include a variety of different shapes; or, the discrete figures may all have the same shape; wherein, the discrete figures may include circles, ellipses and / or polygons.

[0010] Optionally, the interval between two adjacent discrete graphics in a plurality of discrete graphics may be greater than or equal to 0.01 micrometers; and / or, The feature dimensions of the discrete graphic are greater than or equal to 0.01 micrometers; and / or, The thickness of the temperature compensation layer ranges from 0.1 nanometers to 1000 nanometers.

[0011] Optionally, the temperature compensation layer is disposed in any one of the bottom electrode, the piezoelectric layer, and the top electrode; or, A temperature compensation layer is disposed between the top electrode and the piezoelectric layer; or, A temperature compensation layer is disposed between the bottom electrode and the piezoelectric layer.

[0012] Optionally, the temperature compensation layer can be multiple layers, which are spaced apart along the thickness direction of the piezoelectric resonant structure.

[0013] Optionally, the multilayer temperature compensation layer may also include a continuously distributed patterned structure; Among them, the temperature compensation layer with a continuously distributed patterned structure and the temperature compensation layer with multiple discrete patterned structures are staggered along the thickness direction of the piezoelectric resonant structure.

[0014] Optionally, the bulk acoustic resonator further includes a planarization layer, which fills the space between multiple discrete patterns of the temperature compensation layer, and the upper surface of the planarization layer is coplanar with the upper surface of the discrete patterns.

[0015] In some embodiments, a method for manufacturing a bulk acoustic resonator is provided, comprising: A piezoelectric resonant structure is formed on a carrier wafer. The piezoelectric resonant structure includes a bottom electrode, a piezoelectric layer, and a top electrode stacked sequentially. In the process of forming the piezoelectric resonant structure, an initial temperature compensation layer is deposited at the target location for forming the temperature compensation layer; The initial temperature compensation layer is processed using a graphical process to form a temperature compensation layer, which is a graphical structure comprising multiple discrete graphics.

[0016] Optionally, the step of forming the temperature compensation layer by processing the initial temperature compensation layer through a patterning process includes: A patterned photoresist layer is formed on the initial temperature-compensated layer; Using a photoresist layer as a mask, the initial temperature compensation layer is etched to form a temperature compensation layer; Among these, the interval between two adjacent discrete graphics in a plurality of discrete graphics ranges from greater than or equal to 0.01 micrometers; and / or, The feature dimensions of the discrete graphic are greater than or equal to 0.01 micrometers; and / or, The thickness of the temperature compensation layer ranges from 0.1 nanometers to 1000 nanometers.

[0017] Optionally, after the step of forming the temperature compensation layer, the method further includes: An insulating material is deposited on the temperature compensation layer to form a filler layer; The filler layer is chemically and mechanically polished until the upper surface of multiple discrete patterns of the temperature compensation layer is exposed, forming a planarized surface.

[0018] In some embodiments, a bulk acoustic wave filter is provided, including: a bulk acoustic wave resonator as described in any of the above embodiments; or a bulk acoustic wave resonator manufactured using the manufacturing method of the bulk acoustic wave resonator as described in any of the above embodiments.

[0019] In some embodiments, an in-vehicle device is provided, including: a bulk acoustic wave resonator as described in any of the above embodiments; or a bulk acoustic wave resonator manufactured using the manufacturing method of the bulk acoustic wave resonator as described in any of the above embodiments.

[0020] The bulk acoustic wave resonator and its manufacturing method, bulk acoustic wave filter, and vehicle-mounted equipment provided in this disclosure can achieve the following technical effects: In this embodiment, by employing the temperature compensation layer of this disclosure, the present invention creates a partially compensated, partially transparent composite region along the acoustic path. During propagation, sound waves are subjected to local perturbations and scattering as they pass through the edges and surfaces of each discrete pattern unit. However, in the gaps between the discrete patterns, the sound waves can propagate almost without loss within the original piezoelectric layer, which possesses excellent acoustic properties. This reduces the total area of ​​the acoustic impedance abrupt change interface, thereby achieving temperature compensation while significantly preserving the high Q-value characteristics and very low insertion loss of the resonator. While achieving temperature compensation, it avoids the severe quality factor degradation and significantly increased insertion loss problems caused by traditional continuous temperature compensation layers.

[0021] The above general description and the description below are exemplary and illustrative only and are not intended to limit this application. Attached Figure Description

[0022] One or more embodiments are illustrated by way of example with reference to the accompanying drawings. These illustrations and drawings do not constitute a limitation on the embodiments. Elements having the same reference numerals in the drawings are shown as similar elements. The drawings are not to be scaled. And wherein: Figure 1 This is a cross-sectional view of a bulk acoustic resonator provided in an embodiment of this disclosure; Figure 2 This is a cross-sectional view of another bulk acoustic resonator provided in an embodiment of this disclosure; Figure 3 This is a schematic diagram of the horizontal plane where a temperature compensation layer is located in a bulk acoustic resonator provided in this embodiment of the present disclosure; Figure 4 This is a schematic diagram of the horizontal plane where another temperature compensation layer is located in the bulk acoustic resonator provided in this embodiment of the present disclosure; Figure 5 This is a schematic diagram of the horizontal plane where another temperature compensation layer is located in the bulk acoustic resonator provided in this embodiment of the present disclosure; Figure 6 This is a cross-sectional view of yet another bulk acoustic resonator provided in this embodiment; Figure 7 This is a cross-sectional view of yet another bulk acoustic resonator provided in this embodiment; Figure 8 This is a cross-sectional view of yet another bulk acoustic resonator provided in this embodiment; Figure 9 This is a cross-sectional view of yet another bulk acoustic resonator provided in this embodiment; Figure 10 This is a transmission characteristic curve of a bulk acoustic resonator in the prior art; Figure 11 This is a transmission characteristic curve of the bulk acoustic resonator provided in the embodiments of this disclosure; Figure 12 This is a schematic flowchart of a method for manufacturing a bulk acoustic resonator according to an embodiment of this disclosure; Figure 13 This is a schematic flowchart of another method for manufacturing a bulk acoustic resonator provided in this embodiment of the present disclosure; Figure 14 yes Figure 13 A schematic diagram of the deposited electrical structure layer in the illustrated embodiment; Figure 15 yes Figure 13 A schematic diagram of a graphical structure that forms multiple discrete graphics in the illustrated embodiment; Figure 16 yes Figure 13 A schematic diagram illustrating the formation of a planarized surface in the illustrated embodiment; Figure 17 yes Figure 13 A schematic diagram illustrating the region boundary defining the continuous sacrificial layer in the illustrated embodiment; Figure 18 yes Figure 13 A schematic diagram of the preliminary cavity structure in the illustrated embodiment; Figure 19 yes Figure 13 The diagram shown illustrates the formation of the cutoff boundary layer in the embodiment. Figure 20 yes Figure 13 A schematic diagram of the bonding contact layer in the illustrated embodiment; Figure 21 yes Figure 13 The illustrated embodiment is a schematic diagram of bonding the device wafer and the carrier wafer through their planarized surfaces. Figure 22 yes Figure 13 A schematic diagram showing the complete removal of the original carrier wafer in the illustrated embodiment; Figure 23 yes Figure 13 The illustrated embodiment is a schematic diagram of etching the exposed top electrode metal layer to achieve electrical isolation; Figure 24 yes Figure 13 A schematic diagram of the embodiment shown, in which a metal layer is deposited and an external electrical pad connected to the top / bottom electrode is formed by a stripping process; Figure 25 yes Figure 13 A schematic diagram of the suspended structure in the illustrated embodiment.

[0023] Figure label: One-piece acoustic resonator; 110 carrier substrate; 120 piezoelectric resonant structure; 121 bottom electrode; 122 piezoelectric layer; 123 top electrode; 130 Temperature compensation layer; 131 Discrete pattern; 132 Continuously distributed temperature compensation layer; 140 Sacrificial layer; 150 Cut-off boundary layer; 160 Bonding contact layer; 170 Carrier wafer; 180 Support wafer; 190 Cavity. Detailed Implementation

[0024] To provide a more detailed understanding of the features and technical content of the embodiments of this disclosure, the implementation of the embodiments of this disclosure will be described in detail below with reference to the accompanying drawings. The accompanying drawings are for illustrative purposes only and are not intended to limit the embodiments of this disclosure. In the following technical description, for ease of explanation, several details are used to provide a full understanding of the disclosed embodiments. However, one or more embodiments may still be implemented without these details. In other cases, well-known structures and devices may be simplified in their depiction to simplify the drawings.

[0025] The terms "first," "second," etc., used in the technical solutions described in this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate for the embodiments of this disclosure described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion.

[0026] Unless otherwise stated, the term "multiple" means two or more.

[0027] In this embodiment of the disclosure, the character " / " indicates that the objects before and after it are in an "or" relationship. For example, A / B means: A or B.

[0028] The term "and / or" describes an association between objects, indicating that three relationships can exist. For example, A and / or B means: A or B, or A and B.

[0029] The term "correspondence" can refer to an association or binding relationship. The correspondence between A and B means that there is an association or binding relationship between A and B.

[0030] In some embodiments, combined with Figure 1 and Figure 2 , Figures 6 to 9 As shown, a bulk acoustic wave resonator 1 is provided, including: a carrier substrate 110; a piezoelectric resonant structure 120 disposed on the carrier substrate 110, the piezoelectric resonant structure 120 including a bottom electrode 121, a piezoelectric layer 122 and a top electrode 123 sequentially stacked on the carrier substrate 110; and a temperature compensation layer 130 disposed within the piezoelectric resonant structure 120; wherein the temperature compensation layer 130 is a patterned structure including multiple discrete patterns 131.

[0031] The bulk acoustic wave resonator 1 disclosed herein includes: a carrier substrate 110, a piezoelectric resonant structure 120, and a temperature compensation layer 130. The carrier substrate 110 provides mechanical support and a thermal management substrate for the device. The piezoelectric resonant structure 120 includes a bottom electrode 121, a piezoelectric layer 122, and a top electrode 123. The bottom electrode 121 and the top electrode 123 are used to apply an excitation electric field and extract an electrical signal. The piezoelectric layer 122, sandwiched between the two electrodes, is an active material layer that enables the conversion between electrical energy and mechanical energy, such as aluminum nitride. The temperature compensation layer 130 is disposed inside the piezoelectric resonant structure 120. The temperature compensation layer 130 of this disclosure is not a continuous, complete thin film as in related technologies, but is constructed as a patterned structure containing multiple discrete patterns 131. That is, in the embodiments of this disclosure, the temperature compensation material is discontinuous in the plane and is divided into multiple mutually separated units or patterns. The temperature compensation layer material has a frequency temperature coefficient opposite to that of the piezoelectric layer 122, such as silicon dioxide. By integrating the temperature compensation layer material in the form of discrete pattern 131 into the sound wave propagation path, the harmful, continuous heterogeneous interface is divided into multiple isolated, local interfaces. This can actively and locally adjust the equivalent stiffness of the resonant structure as a function of temperature, thereby compensating for the inherent frequency temperature drift of the piezoelectric material, reducing the frequency temperature coefficient of the resonator, and improving its frequency stability under different ambient temperatures.

[0032] By employing the temperature compensation layer 130 of this disclosure, the present invention creates a partially compensated, partially transparent composite region along the acoustic path. During propagation, sound waves are subject to localized disturbances and scattering as they pass through the edges and surfaces of each discrete pattern 131 unit. However, in the gaps between the discrete patterns 131, the sound waves propagate almost without loss within the original piezoelectric layer 122, which possesses excellent acoustic properties. This reduces the total area of ​​the acoustic impedance abrupt change interface, thereby achieving temperature compensation while significantly preserving the high Q-value characteristics and very low insertion loss of the resonator. While achieving temperature compensation, the serious degradation of the quality factor and the significant increase in insertion loss caused by traditional continuous temperature compensation layers are avoided.

[0033] Optionally, combined Figure 3 , Figure 4 and Figure 5 As shown, multiple discrete patterns 131 are arranged in an array within the effective region of the piezoelectric resonant structure 120.

[0034] In this embodiment, the effective region of the piezoelectric resonant structure 120 refers to the acoustic vibration region that plays a major role in resonance, typically the overlapping portion of the upper and lower electrodes. Multiple discrete patterns 131 are arranged in an array, ensuring that the temperature compensation material with a positive temperature coefficient acts uniformly and consistently throughout the entire resonator vibration region. When the sound wave forms a standing wave within the resonant cavity, both its antinodes and nodes experience equal and regular local stiffness modulation, avoiding resonant frequency splitting, modal disturbances, or localized thermal stress concentration caused by uneven spatial distribution of the compensation effect. This improves the overall and uniform frequency temperature coefficient compensation for the entire resonant mode.

[0035] Optionally, the array type includes, but is not limited to, rectangular arrays, hexagonal arrays, etc.

[0036] Optionally, combined Figure 4 As shown, the multiple discrete graphics 131 include graphics of various different shapes.

[0037] In this embodiment, the discrete pattern 131 comprises two or more geometric shapes. For example, the discrete pattern 131 includes circles and ellipses, which are arranged in an alternating array. Alternatively, the discrete pattern 131 includes circles, squares, and ellipses, which are grouped together and arranged in a rectangular array. By using combinations of different shapes, different temperature compensation intensities and acoustic characteristics can be set in different regions. For example, in the central region where acoustic energy is dense, a pattern with a higher fill rate or a shape that is more likely to cause acoustic wave coupling, such as a thin strip, can be used to provide strong compensation; in the edge region, a pattern with a lower fill rate can be used to reduce losses and optimize overall performance.

[0038] Optionally, combined Figure 3 As shown, multiple discrete figures 131 have the same shape.

[0039] In this embodiment, all discrete patterns 131 employ the same geometry, such as circles or squares. A single shape minimizes manufacturing complexity, improves the consistency of pattern size and contour across the entire wafer, thereby enhancing production yield and device parameter uniformity. Furthermore, a regular array of single shapes generates a highly uniform and predictable acoustic perturbation field. This uniformity helps maintain the purity of resonant modes, thus improving the balance between compensating for temperature drift and maintaining a high Q value.

[0040] Combination Figure 5 As shown, the multiple discrete figures 131 are all rectangles, and the rectangles have two sizes, which are arranged in an array. Optionally, the smaller rectangles can be replaced with other shapes, such as circles or ellipses.

[0041] Optionally, the discrete graphic 131 can be a circle, an ellipse, and / or a polygon.

[0042] In this embodiment, the circle has isotropic and continuously smooth edges. When sound waves encounter a circular shape, their scattering is uniform and predictable, without the strong diffraction and stress concentration points caused by sharp edges. This makes it the choice of shape that introduces the least additional acoustic loss and is most conducive to maintaining the high quality factor Q value of the resonator. It minimizes sound wave scattering loss while achieving necessary temperature compensation and is easy to manufacture with high precision.

[0043] The major and minor axes of the ellipse define the dominant directions of its acoustic and mechanical properties. The equivalent perturbation to sound wave propagation differs along the major and minor axes. This property can be used to compensate for slight anisotropy that may exist in piezoelectric films or electrodes themselves, or to consciously and gently shape the sound field distribution without introducing strong directional abrupt changes like those of a polygon. The smooth edges of the ellipse better accommodate and relax thermal mismatch stresses in specific directions, and its shape provides a gradual stress release path.

[0044] Polygons are a common basic shape for constructing phononic crystals or acoustic metamaterial units. By designing the side lengths, angles, and arrangement periods of polygons, band gaps can be created for sound wave propagation in specific frequency bands, thereby actively and effectively suppressing unwanted stray modes and transverse resonances. Polygons include, but are not limited to, squares and regular hexagons. Furthermore, by adjusting the size of the polygonal unit, the filling ratio of temperature compensation material throughout the entire area can be controlled, thereby improving the fine and linear control of temperature compensation intensity.

[0045] Circular and elliptical shapes, due to their lack of sharp corners, help reduce sound wave diffraction and scattering at the edges of the shape, further reducing losses. Other shapes, such as polygons, offer design flexibility and can be used to tune the sound field distribution. Combinations of different shapes can achieve more complex acoustic modulation.

[0046] Optionally, combined Figure 1 As shown, the value of the spacing dimension 'a' between two adjacent discrete patterns 131 in the plurality of discrete patterns 131 is greater than or equal to 0.01 micrometers; and / or, The value of the graphic feature dimension b of discrete graphic 131 is greater than or equal to 0.01 micrometers; and / or, The thickness h of the temperature compensation layer 130 ranges from 0.1 nm to 1000 nm.

[0047] In this embodiment, the lower limit of the spacing between two adjacent discrete patterns 131 is 0.01 micrometers, and the lower limit of the feature size of the discrete pattern 131 is also 0.01 micrometers. This avoids pattern adhesion, distortion, or uncontrolled edge roughness caused by excessively dense patterns or excessively small features. Simultaneously, this size range ensures that the etching process has a sufficient process window to clearly define the pattern sidewalls, thereby obtaining discrete patterns 131 with controllable shape and size. This makes the patterned temperature-compensated layer structure compatible with mainstream semiconductor manufacturing processes, improving the yield of large-scale production.

[0048] The thickness of the temperature compensation layer 130 ranges from 0.1 nm to 1000 nm, allowing for the setting of an appropriate thickness based on the compensation intensity. Furthermore, by combining feature dimensions and spacing, the fill rate of the pattern can be adjusted to control the proportion of the temperature compensation material in the acoustic path, thereby achieving linear or nonlinear control of the temperature compensation intensity to meet the requirements of different application scenarios.

[0049] Furthermore, the spacing between adjacent discrete patterns 131 within the multiple discrete patterns 131 is greater than or equal to 0.01 micrometers, ensuring a sufficiently wide low-loss acoustic channel between the patterns, allowing sound waves to propagate almost without scattering. The lower limit of the feature size prevents the pattern units from becoming too small, approaching a continuous film, thus preventing losses caused by diffraction and mode conversion on extremely small patterns. The thickness range prevents excessively thick temperature compensation layers from causing excessively long paths for sound waves through heterogeneous materials, introducing excessive volume losses. Thus, these three factors work together to achieve temperature compensation while minimizing the additional acoustic losses introduced by the patterned structure, bringing the resonator's quality factor Q and the filter's insertion loss close to the level of the un-temperature-compensated layer.

[0050] Optionally, combined Figure 1 , Figure 7 and Figure 9 As shown, the temperature compensation layer 130 is disposed in any one of the bottom electrode 121, the piezoelectric layer 122, and the top electrode 123.

[0051] In this embodiment, the temperature compensation layer 130 is located inside any one of the bottom electrode 121, the piezoelectric layer 122, and the top electrode 123. It becomes an integral part of the electrode or piezoelectric layer 122 body through doping, composite formation, or patterning replacement. For example, during electrode deposition, a local region composed of a temperature compensation material is formed through a patterning process. This region functionally belongs to the electrode layer but has temperature compensation characteristics in terms of material properties.

[0052] For example, by graphically integrating temperature-compensating material within the electrode layer, this area simultaneously serves the dual functions of conductivity and temperature compensation. This design allows for localized adjustment of the electrode's equivalent stiffness, density, and stress, enabling finer acoustic impedance matching and frequency temperature coefficient compensation.

[0053] For example, if the temperature compensation material is patterned and integrated inside the piezoelectric layer 122, the temperature compensation effect acts on the main medium of piezoelectric vibration, which makes the regulation of the acoustic phase velocity more direct and efficient, which is beneficial to optimizing the thickness vibration mode and may suppress transverse coupling.

[0054] Optionally, combined Figure 8 As shown, a temperature compensation layer 130 is disposed between the top electrode 123 and the piezoelectric layer 122. Alternatively, in combination with... Figure 6 As shown, the temperature compensation layer 130 is disposed between the bottom electrode 121 and the piezoelectric layer 122.

[0055] In this embodiment, a temperature compensation layer 130 is disposed between the electrode and the piezoelectric layer 122 to achieve strong and direct temperature compensation. When sound waves propagate between the electrode and the piezoelectric layer 122, they pass through the inserted temperature compensation layer 130. The temperature compensation layer 130 induces a phase delay and velocity change in the sound wave propagation, thereby effectively adjusting the temperature dependence of the resonant frequency.

[0056] By placing the temperature compensation layer in different positions, its influence on the longitudinal electric field distribution and the transverse sound field distribution can be adjusted, thus providing multiple ways to optimize the balance between the electromechanical coupling coefficient and the temperature compensation coefficient.

[0057] Optionally, combined Figure 2 As shown, the temperature compensation layer 130 is multi-layered, and the multi-layered temperature compensation layer 130 is distributed at intervals along the thickness direction of the piezoelectric resonant structure 120.

[0058] In this embodiment, a composite structure consisting of multiple mutually separated patterned temperature compensation layers is introduced along the vertical dimension of the piezoelectric resonant structure 120, thereby achieving stronger and wider frequency stability over a wider temperature range. By setting multiple layers, each contributing a portion of the compensation, the effects are cumulative along the acoustic path. This allows the total compensation capability to be multiplied without significantly increasing the thickness and loss of a single layer, thus improving the compensation effect on the frequency temperature coefficient of the resonator. Sound waves exist in the resonant cavity as three-dimensional standing waves, with different sound pressure and particle velocity distributions at different depths. By setting temperature compensation layers with different pattern parameters at different depths, targeted compensation can be performed for specific acoustic states at those depths. For example, a layer with strong compensation effect can be set in the antinode region of the sound pressure wave, while a layer with weak compensation effect can be set in the node region, achieving gradient compensation that matches the sound field distribution, resulting in higher efficiency and fewer side effects.

[0059] Furthermore, the thermal expansion coefficients of the temperature compensation material differ from those of the surrounding materials, which can generate stress when the temperature changes. Dividing the total compensation material into multiple layers and spacing them apart improves thermomechanical reliability and optimizes stress distribution, enhances the long-term reliability of the device under temperature cycling, and improves the thin film stress state.

[0060] Optionally, combined Figure 2 As shown, the multilayer temperature compensation layer 130 also includes a continuously distributed patterned structure; wherein, the temperature compensation layer 130 with a continuously distributed patterned structure and the temperature compensation layer 130 with a patterned structure of multiple discrete patterns 131 are staggered along the thickness direction of the piezoelectric resonant structure 120.

[0061] In this embodiment, among the multilayer temperature compensation layers, at least one layer has a continuously distributed patterned structure rather than a discrete one. The continuously distributed temperature compensation layer 132 and the discrete patterned temperature compensation layer 131 are alternately arranged along the thickness direction. The continuously distributed temperature compensation layer 132, due to its complete material coverage, directly modulates the acoustic phase velocity, significantly reducing the overall frequency temperature coefficient. The patterned structure of the discrete patterned layer 131 is used to repair the acoustic impedance mismatch and interface scattering introduced by the continuous layer, allowing for fine-tuning of local enhancement or reduction of the continuous layer. The periodic alternation of the continuous and discrete layers optimizes the energy localization of the principal thickness stretching mode, improving the effective electromechanical coupling coefficient and quality factor.

[0062] Optionally, the bulk acoustic resonator 1 further includes a planarization layer, which fills the space between a plurality of discrete patterns 131 of the temperature compensation layer 130, and the upper surface of the planarization layer is coplanar with the upper surface of the discrete patterns 131.

[0063] In this embodiment, a planarization layer is filled between multiple discrete patterns 131 of the temperature compensation layer 130 to fill the surface grooves or gaps caused by the discrete patterns 131 of the temperature compensation layer. The upper surface of the planarization layer is coplanar with the upper surface of the discrete patterns 131, that is, after the planarization process, the surface of the filling material and the top surface of the retained temperature compensation layer pattern units are at the same horizontal level, forming a flat and continuous surface. This avoids uncontrollable sound wave scattering and electric field distortion caused by surface undulations.

[0064] For example, transmission characteristic tests were conducted on the bulk acoustic wave resonator 1 without a temperature compensation layer 130 and the bulk acoustic wave resonator 1 provided in this disclosure within a wide temperature range of -45℃ to 85℃. The resulting transmission characteristic curves are shown below. Figure 10 and Figure 11 As shown. Figure 10 The figure shown is a transmission characteristic curve of a prior art bulk acoustic resonator 1. Figure 11 The figure shown is a transmission characteristic curve of the bulk acoustic resonator 1 provided in this disclosure.

[0065] Combination Figure 10 and Figure 11 As shown, the resonator employing the patterned temperature compensation layer structure of this disclosure has its resonant frequency shift controlled to within less than 0.5 MHz. In contrast, prior art resonators without a temperature compensation layer exhibit frequency shifts as high as 3 MHz under the same conditions. The corresponding frequency temperature coefficient is optimized from approximately -20 ppm / ℃ to approximately 3 ppm / ℃. That is, this disclosure, by setting a temperature compensation layer 130 with multiple discrete patterns 131, embeds compensation material with a positive temperature coefficient into the acoustic path, forming periodic modulation, thereby efficiently and uniformly offsetting the inherent negative temperature coefficient effect of piezoelectric materials, thus solving the problem of device core parameters drifting with ambient temperature.

[0066] While achieving the aforementioned improvement in temperature stability, experimental data show that, compared to a reference device without any temperature compensation layer, the resonator using the patterned temperature compensation layer structure disclosed herein exhibits an additional insertion loss change δIL < 0.2 dB. That is, compared to a continuous temperature compensation layer which introduces a large area of ​​acoustic impedance mismatch interface, leading to severe acoustic wave scattering and energy loss, the patterned design of this invention transforms the continuous loss interface into discrete, localized perturbation points, while preserving the original low-loss propagation channels between the patterns. This structure allows the vast majority of acoustic wave energy to pass through with low loss, thus achieving a coexistence of strong compensation and low loss at the system level, breaking the long-standing performance trade-off dilemma in this field.

[0067] In some embodiments, combined with Figure 12 As shown, a method for manufacturing a bulk acoustic resonator 1 is provided, comprising: S801, a piezoelectric resonant structure is formed on the carrier wafer. The piezoelectric resonant structure includes a bottom electrode, a piezoelectric layer and a top electrode stacked in sequence. In the process of forming the piezoelectric resonant structure, an initial temperature compensation layer is deposited at the target location for forming the temperature compensation layer; S802 processes the initial temperature compensation layer using a graphical process to form a temperature compensation layer, which is a graphical structure comprising multiple discrete graphics.

[0068] The method for manufacturing the bulk acoustic wave resonator 1 disclosed herein involves sequentially forming a stacked structure of a bottom electrode 121, a piezoelectric layer 122, and a top electrode 123 on a carrier wafer 170. During the formation of the piezoelectric resonator structure 120, a temperature compensation material thin film, i.e., a temperature compensation initial layer, is deposited at the target location for forming the temperature compensation layer 130 using thin film deposition technology. The temperature compensation initial layer is then subjected to a patterning process, which includes photolithography and etching. Photolithography defines a mask for the desired discrete pattern 131, while etching removes the temperature compensation material from unprotected areas, thereby transforming the continuous temperature compensation initial layer into a patterned structure composed of multiple discrete patterns 131.

[0069] Optionally, the step of forming the temperature compensation layer 130 by processing the initial temperature compensation layer through a patterning process includes: A patterned photoresist layer is formed on the initial temperature-compensated layer; Using a photoresist layer as a mask, the initial temperature compensation layer is etched to form a temperature compensation layer 130; Among them, the interval size between two adjacent discrete patterns 131 in the plurality of discrete patterns 131 is greater than or equal to 0.01 micrometers; and / or, The value range of the graphic feature size of discrete graphic 131 is greater than or equal to 0.01 micrometers; and / or, The thickness of the temperature compensation layer 130 ranges from 0.1 nanometers to 1000 nanometers.

[0070] In this embodiment, a patterned photoresist layer is formed on the initial temperature compensation layer. Specifically, photoresist is coated onto a deposited continuous temperature compensation material film, and the discrete pattern array 131 designed on the mask is transferred to the photoresist through exposure and development processes, forming a physical mask with a corresponding windowed pattern. Using the photoresist layer as a mask, the initial temperature compensation layer is etched to form a temperature compensation layer 130. That is, using the patterned photoresist as a protective layer, the temperature compensation material in areas not covered by the photoresist is selectively removed through dry or wet etching processes. After etching, the photoresist is removed, resulting in a discrete pattern array 131 composed of temperature compensation material consistent with the designed pattern.

[0071] Furthermore, the spacing between adjacent discrete patterns 131 is greater than or equal to 0.01 micrometers. If the spacing is too small, the propagation of sound waves between the patterns will be limited by the narrow area, resulting in additional acoustic impedance and loss. This lower limit ensures the smooth flow of low-loss channels. The feature size of the discrete pattern 131 is greater than or equal to 0.01 micrometers. This parameter is determined by the minimum resolvable feature size of the photolithography and the anisotropic control capability of the etching, ensuring that the pattern can be clearly defined and transferred. The thickness of the temperature compensation layer 130 ranges from 0.1 nanometers to 1000 nanometers, allowing the physical thickness of the temperature compensation layer to be minimized while meeting the compensation requirements. A thinner heterostructure means that the path required for sound waves to traverse it is shorter, thereby minimizing the acoustic energy loss introduced by the bulk material itself.

[0072] Optionally, after the step of forming the temperature compensation layer 130, the method further includes: depositing an insulating material on the temperature compensation layer 130 to form a filler layer; and performing chemical mechanical polishing on the filler layer until the upper surface of the plurality of discrete patterns 131 of the temperature compensation layer 130 is exposed to form a planarized surface.

[0073] In this embodiment, an insulating dielectric material, such as silicon oxide or silicon nitride, is deposited conformally or non-conformally above the etched patterned temperature compensation layer. The insulating dielectric material flows into and completely fills all gaps between the temperature compensation patterns, covering the entire area to form a continuous thin film layer. Using chemical mechanical polishing (CMP), the excessively thick filler material deposited in the previous step is uniformly removed through the combined action of chemical etching and mechanical grinding until the upper surfaces of the multiple discrete patterns 131 of the temperature compensation layer 130 are exposed, forming a planarized surface. This eliminates surface height differences and topological undulations caused by the patterned structure, allowing the subsequently deposited piezoelectric layer 122, electrodes, or other functional thin films to grow continuously with optimal crystal quality under completely uniform stress.

[0074] In some examples, combined Figure 13 As shown, the manufacturing process of the temperature-compensated patterned bulk acoustic resonator 1 is as follows: S901, on the carrier wafer 170, sequentially deposited and patterned to form the electrical structure layers of the resonator: bottom electrode, piezoelectric layer 122, and top electrode, as shown in the figure. Figure 14 As shown.

[0075] S902, a temperature compensation material thin film is deposited above the bottom electrode, and then the thin film is patterned using photolithography and etching processes to form a patterned structure with multiple discrete patterns 131, such as... Figure 15 As shown.

[0076] S903, a boundary definition layer film is deposited above the patterned temperature compensation layer 130, followed by chemical mechanical polishing to form a planarized surface, such as... Figure 16 As shown.

[0077] S904, the aforementioned planarized boundary definition layer is etched to define the region boundary of the subsequent sacrificial layer 140, as follows: Figure 17 As shown.

[0078] S905, deposited phosphosilicate glass as the sacrificial layer 140, and etched onto it to initially form the prototype structure of cavity 190, such as... Figure 18 As shown.

[0079] In S906, a layer of polysilicon is deposited on the sacrificial layer 140 to form a cutoff boundary layer 150, which serves as a support and transition layer for subsequent processes, such as... Figure 19 As shown.

[0080] S907, deposit an undoped silicon dioxide layer, and then perform chemical mechanical polishing again to form an extremely flat and strong bonded contact layer 160, such as Figure 20 As shown.

[0081] S908, the processed device wafer and carrier wafer 180 are bonded together through their planarized surfaces, as follows: Figure 21 As shown.

[0082] S909, through techniques such as grinding and etching, completely removes the original carrier wafer 170, exposing the bottom electrode side of the device structure, such as... Figure 22 As shown.

[0083] S910 etches the exposed top electrode metal layer to achieve electrical isolation, such as... Figure 23 As shown.

[0084] S911, the piezoelectric layer 122 is etched to define the boundary of the active region of the resonator. At the same time, a release hole is etched to create a channel for the subsequent removal of the sacrificial layer 140.

[0085] S912, combined with Figure 24 The metal layer is deposited, and an external electrical pad connected to the top / bottom electrode is formed by a stripping process.

[0086] S913, through the release hole, uses vapor phase or wet etching techniques to completely remove the internal phosphosilicate glass sacrificial layer 140, thereby forming the final suspended structure, namely the critical cavity 190 for resonator operation, such as... Figure 25 As shown.

[0087] In some embodiments, a bulk acoustic wave filter is provided, including: a bulk acoustic wave resonator 1 as described in any of the above embodiments; or, a bulk acoustic wave resonator 1 manufactured using the manufacturing method of the bulk acoustic wave resonator 1 as described in any of the above embodiments.

[0088] The bulk acoustic wave filter provided in this disclosure includes a bulk acoustic wave resonator 1 as described in any of the above embodiments; or, a bulk acoustic wave resonator 1 manufactured using the manufacturing method of the bulk acoustic wave resonator 1 as described in any of the above embodiments. Therefore, it has all the beneficial effects of the bulk acoustic wave resonator 1 or the bulk acoustic wave resonator 1 manufactured using the manufacturing method of the bulk acoustic wave resonator 1, which will not be repeated here.

[0089] In some embodiments, an in-vehicle device is provided, including: a bulk acoustic wave resonator 1 as described in any of the above embodiments; or, a bulk acoustic wave resonator 1 manufactured using the manufacturing method of the bulk acoustic wave resonator 1 as described in any of the above embodiments.

[0090] The vehicle-mounted device provided in this disclosure includes a bulk acoustic wave resonator 1 as described in any of the above embodiments; or a bulk acoustic wave resonator 1 manufactured using the manufacturing method of the bulk acoustic wave resonator 1 as described in any of the above embodiments. Therefore, it has all the beneficial effects of the bulk acoustic wave resonator 1 or the bulk acoustic wave resonator 1 manufactured using the manufacturing method of the bulk acoustic wave resonator 1, which will not be repeated here.

[0091] The foregoing description and accompanying drawings fully illustrate embodiments of this disclosure to enable those skilled in the art to practice them. Other embodiments may include structural, logical, electrical, procedural, and other changes. The embodiments represent only possible variations. Individual components and functions are optional unless explicitly required, and the order of operation may vary. Parts and features of some embodiments may be included in or replace parts and features of other embodiments. Moreover, the terminology used in this application is for describing embodiments only and is not intended to limit the technical solutions described herein. As used in the technical solutions described herein, the singular forms “a,” “an,” and “the” are intended to equally include the plural forms unless the context clearly indicates otherwise. Similarly, the term “and / or” as used herein refers to any and all possible combinations of one or more of the associated listed elements. Additionally, when used in this application, the term "comprise" and its variations "comprises" and / or "comprising" refer to the presence of stated features, integrals, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components, and / or groups thereof. Without further limitations, an element defined by the phrase "comprises a..." does not exclude the presence of other identical elements in the process, method, or apparatus that includes said element. In this document, each embodiment may focus on the differences from other embodiments, and similar or identical parts between embodiments can be referred to mutually. For methods, products, etc., disclosed in the embodiments, if they correspond to the method section disclosed in the embodiments, the relevant parts can be referred to the description of the method section.

Claims

1. A bulk acoustic resonator, characterized in that, include: carrier substrate; A piezoelectric resonant structure is disposed on a carrier substrate. The piezoelectric resonant structure includes a bottom electrode, a piezoelectric layer and a top electrode that are sequentially stacked on the carrier substrate. A temperature compensation layer is disposed within the piezoelectric resonant structure; The temperature compensation layer comprises a graphical structure of multiple discrete graphics.

2. The bulk acoustic resonator according to claim 1, characterized in that, Multiple discrete patterns are arranged in an array within the effective region of the piezoelectric resonant structure.

3. The bulk acoustic resonator according to claim 1, characterized in that, Multiple discrete figures include various different shapes; or, multiple discrete figures have the same shape. Discrete graphics include circles, ellipses, and / or polygons.

4. The bulk acoustic resonator according to any one of claims 1 to 3, characterized in that, The interval between two adjacent discrete graphics in a plurality of discrete graphics is greater than or equal to 0.01 micrometers; and / or, The feature dimensions of the discrete graphic are greater than or equal to 0.01 micrometers; and / or, The thickness of the temperature compensation layer ranges from 0.1 nanometers to 1000 nanometers.

5. The bulk acoustic resonator according to any one of claims 1 to 3, characterized in that, The temperature compensation layer is disposed in any one of the bottom electrode, piezoelectric layer, and top electrode; or, A temperature compensation layer is disposed between the top electrode and the piezoelectric layer; or, A temperature compensation layer is disposed between the bottom electrode and the piezoelectric layer.

6. The bulk acoustic resonator according to any one of claims 1 to 3, characterized in that, The temperature compensation layer consists of multiple layers, which are spaced apart along the thickness direction of the piezoelectric resonant structure.

7. The bulk acoustic resonator according to claim 6, characterized in that, The multilayer temperature compensation layer also includes a continuously distributed patterned structure; Among them, the temperature compensation layer with a continuously distributed patterned structure and the temperature compensation layer with multiple discrete patterned structures are staggered along the thickness direction of the piezoelectric resonant structure.

8. A method for manufacturing a bulk acoustic resonator, characterized in that, include: A piezoelectric resonant structure is formed on a carrier wafer. The piezoelectric resonant structure includes a bottom electrode, a piezoelectric layer, and a top electrode stacked sequentially. In the process of forming the piezoelectric resonant structure, an initial temperature compensation layer is deposited at the target location for forming the temperature compensation layer; The initial temperature compensation layer is processed using a graphical process to form a temperature compensation layer, which is a graphical structure comprising multiple discrete graphics.

9. The manufacturing method according to claim 8, characterized in that, The steps for forming a temperature compensation layer by processing the initial temperature compensation layer using a patterning process include: A patterned photoresist layer is formed on the initial temperature-compensated layer; Using a photoresist layer as a mask, the initial temperature compensation layer is etched to form a temperature compensation layer; Among these, the interval between two adjacent discrete graphics in a plurality of discrete graphics ranges from greater than or equal to 0.01 micrometers; and / or, The feature dimensions of the discrete graphic are greater than or equal to 0.01 micrometers; and / or, The thickness of the temperature compensation layer ranges from 0.1 nanometers to 1000 nanometers.

10. The manufacturing method according to claim 9, characterized in that, Following the step of forming the temperature compensation layer, the following steps are also included: An insulating material is deposited on the temperature compensation layer to form a filler layer; The filler layer is chemically and mechanically polished until the upper surface of multiple discrete patterns of the temperature compensation layer is exposed, forming a planarized surface.

11. A bulk acoustic wave filter, characterized in that, include: The bulk acoustic resonator as described in any one of claims 1 to 7; or, A bulk acoustic resonator manufactured using the manufacturing method of a bulk acoustic resonator as described in any one of claims 8 to 10.

12. A vehicle-mounted device, characterized in that, include: The bulk acoustic resonator as described in any one of claims 1 to 7; or, A bulk acoustic resonator manufactured using the manufacturing method of a bulk acoustic resonator as described in any one of claims 8 to 10.

Images