This present disclosure claims the priority to Chinese patent application No. 202210027314.5, entitled “Single crystal film bulk acoustic resonator, manufacturing method for single crystal film bulk acoustic resonator, and filter”, and filed on Jan. 11, 2022 in China, which is hereby incorporated by reference in its entirety.
The present disclosure relates to the technical field of filters, in particular to a single crystal film bulk acoustic resonator, a manufacturing method for a single crystal film bulk acoustic resonator, and a filter.
A film bulk acoustic resonator generates resonance by using a piezoelectric effect of a piezoelectric crystal. Since the resonance is generated by a mechanical wave, rather than taking an electromagnetic wave as a source, the wavelength of the mechanical wave is much shorter than that of electromagnetic wave. Therefore, the size of the film bulk acoustic resonator is greatly reduced compared with the size of a conventional electromagnetic filter. In one aspect, the crystal orientation growth of the piezoelectric crystal can be well controlled at present, so the loss of the resonator is extremely low, the quality factor is high, which can meet the complex design requirements such as steep transition band, low insertion loss, and the like. Since the film bulk acoustic resonator has the characteristics of small size, high roll-off, low insertion loss, and the like, filters based on this core have been widely used in communication systems.
The existing single crystal film bulk acoustic resonator will adopt a bonding process during manufacturing. However, in the actual bonding process, it is difficult to effectively control the bonding area, which is easy to reduce the bonding reliability.
A purpose of the present disclosure is to provide a single crystal film bulk acoustic resonator, a manufacturing method for a single crystal film bulk acoustic resonator, and a filter in view of the abovementioned shortcomings in the related art, which can control the bonding area and improve the bonding reliability.
In order to achieve the abovementioned purpose, the embodiments of the present disclosure adopt the following technical solutions.
In one aspect of the embodiments of the present disclosure, a manufacturing method for a single crystal film bulk acoustic resonator, a manufacturing method for a single crystal film bulk acoustic resonator, and a filter are provided. The method includes that: a temporary base substrate is provided; a buffer layer, a piezoelectric layer, and a first electrode that are stacked on a temporary base substrate are sequentially formed; a first bonding layer is formed on the first electrode; a substrate is provided; the substrate is etched to form a plurality of first bumps on a surface of the substrate; a second bonding layer covering top surfaces of the plurality of first bumps is formed on the surface of the substrate; the second bonding layer located at the top surfaces of the plurality of first bumps is bonded to the first bonding layer; the temporary base substrate is removed; the buffer layer is etched to form a first groove that exposes the piezoelectric layer; and a second electrode that is in contact with the piezoelectric layer is formed through the first groove.
Optionally, after the first bonding layer is formed on the first electrode, the method further includes that: the first bonding layer is patterned to form a plurality of second bumps for bonding with second bonding layer located at the top surfaces of the first bumps.
Optionally, after the temporary base substrate is removed, the method further includes that: the buffer layer and the piezoelectric layer are etched sequentially to form a second groove that exposes the first electrode; and an extraction electrode connected to the first electrode is formed through the second groove.
Optionally, a plurality of first bumps include a first sub-bump and a second sub-bump. A third groove corresponding to a position of the first groove is formed between the first sub-bump and the second sub-bump.
Optionally, both a first bonding layer and a second bonding layer are metal layers.
Optionally, both the first bonding layer and the second bonding layer are metal layers.
Optionally, a sacrificial layer is deposited on the first electrode, and a support layer and the first bonding layer are deposited on the first electrode and the sacrificial layer.
Optionally, a compressed height of the first bonding layer and the second bonding layer after being bonded is not greater than a height of the first bump.
Optionally, the compressed height of the first bonding layer and the second bonding layer after being bonded is equal to the height of the first bump.
Optionally, the bonding pressure applied to the first bonding layer and the second bonding layer is positively related to an area of the top surface of the first bump.
Optionally, a release hole is formed in the substrate, and the sacrificial layer is removed through the release hole to form a cavity.
In another aspect of the embodiments of the present disclosure, a single crystal film bulk acoustic resonator is provided, which includes: a substrate. A surface of the substrate has a plurality of the first bumps. A second bonding layer covering top surfaces of a plurality of first bumps is formed on the surface of the substrate. A first bonding layer is bonded on the second bonding layer. A first electrode, a piezoelectric layer, and a buffer layer that are stacked are sequentially formed on the first bonding layer. A first groove that exposes the piezoelectric layer is formed in the buffer layer. A second electrode that is in contact with the piezoelectric layer is formed on the first groove.
Optionally, both the first bonding layer and the second bonding layer are metal layers.
Optionally, the first bonding layer and the second bonding layer are of same materials. In yet another aspect of the embodiments of the present disclosure, a filter is provided, which includes a plurality of single crystal film bulk acoustic resonators of any one of the above. a plurality of single crystal film bulk acoustic resonators share a same substrate. a plurality of single crystal film bulk acoustic resonators are connected in series and/or in parallel. A first annular sealing structure surrounding the plurality of single crystal film bulk acoustic resonators is formed on the substrate. The first annular sealing structure includes a first sealing ring and a second sealing ring that are stacked on the substrate and are bonded mutually.
Optionally, a second annular sealing structure is also formed on the periphery of the single crystal film bulk acoustic resonators. The second annular sealing structure includes a third sealing ring and a fourth sealing ring that are stacked on the substrate and are bonded mutually.
Optionally, the filter further includes a sealing wall structure. Two adjacent second annular sealing structures are connected through the sealing wall structure.
Optionally, the sealing wall structure includes a fifth sealing ring and a sixth sealing ring that are stacked on the substrate and are bonded mutually.
Optionally, a side wall of the sealing wall structure forms an inclination angle.
Optionally, the angle of the inclination angle is less than 70°.
The present disclosure has the following beneficial effects.
The present disclosure provides a single crystal film bulk acoustic resonator, a manufacturing method for a single crystal film bulk acoustic resonator, and a filter. The method includes: a buffer layer, a piezoelectric layer, and a first electrode that are stacked are sequentially formed on a temporary base substrate; a first bonding layer is formed on the first electrode; a substrate is provided; the substrate is etched to form a plurality of first bumps on a surface of the substrate; a second bonding layer covering top surfaces of the plurality of first bumps is formed on the surface of the substrate; and the second bonding layer located at the top surfaces of the plurality of first bumps are bonded to the first bonding layer. During bonding, the area of the top surfaces of the first bumps can be controlled by etched grooves, so the area of the second bonding layer located at the top surfaces of the first bumps can be controlled, thereby realizing the control of a bonding area. Through the flexible adjustment of the bonding area, a hierarchical structure on the temporary base substrate and a hierarchical structure on the substrate are prevented from being difficult to apply in mass production due to excessive bonding area, high bonding requirement, and high preparation cost on the basis of meeting the requirements of the bonding reliability. In other words, the present disclosure realizes the balance between the bonding requirement and the bonding reliability by controlling the bonding area.
To describe the technical solutions in the embodiments of the present disclosure more clearly, the following briefly introduces the drawings required for describing the embodiments of the present disclosure. It should be understood that the following drawings only show some embodiments of the present disclosure, thus should not be considered as limitation to a scope. Those of ordinary skill in the art may still derive other relevant drawings from these drawings without creative efforts.
Reference signs: 101—temporary base substrate; 102—buffer layer; 103—piezoelectric layer; 204—first electrode; 305—second bump; 401—substrate; 406—etched groove; 507—second bonding layer; 808—second groove; 809—first groove; 910—second electrode; 911—extraction electrode; 912—third groove; 1002—single crystal film bulk acoustic resonator; 1003—first annular sealing structure; 1103—second annular sealing structure; 1104—sealing wall structure; and 307—first bonding layer.
The embodiments stated below represent the information necessary for those skilled in the art to practice the embodiments, and show the best mode to practice the embodiments. After reading the following description with reference to the drawings, those skilled in the art will understand the concepts of the present disclosure, and will recognize the application of these concepts not specifically proposed herein. It is to be understood that these concepts and applications fall within the scope of the present disclosure and the attached claims.
It is to be understood that, the terms first, second, etc. may be used for describing various elements in the present disclosure, but these element should not be limited to these terms. These terms are used only for distinguishing one element from another. For example, without departing from the scope of the present disclosure, a first element may be referred to as a second element, and similarly, the second element may also be referred to as the first element. As used herein, the term “and/or” used herein includes any and all combinations of one or more of the associated listed items.
It is to be understood that when an element (such as a layer, an area, or a substrate) is referred to as “being on another element” or “extending to another element”, it may be directly on another element or directly extend to another element, or there may be an element there between. On the contrary, when on element is referred to as “being directly on another element” or “directly extending to another element”, there is no element there between. Similarly, it is to be understood that when an element (such as a layer, an area, or a substrate) is referred to as “being on another element” or “extending on another element”, it may be directly on another element or directly extend on another element, or there may be an element there between. On the contrary, when an element is referred to as “being directly on another element” or “directly extending on another element”, there is no element there between. It is also understood that when an element is described as being “connected” or “coupled” to another element, it may be directly connected or coupled to another element, or there is an element there between. On the contrary, when an element is referred to as being “directly connected” or “directly coupled” to another element, there is no element there between.
Related terms such as “below” or “above” or “upper” or “lower” or “horizontal” or “vertical” can be used herein for describing the relationship between one element, layer, or area and another element, layer, or area, as shown in the drawings. It is to be understood that these terms and those discussed above are intended to cover different orientations of an apparatus other than those depicted in the drawings.
The terms used in the present disclosure are only used for the purpose of illustrating specific implementation modes, and are not intended to limit the present disclosure. As used herein, singular forms “a”, “an”, and “the” are also intended to include plural forms as well, unless the context explicitly otherwise. It is also to be understood that, when used herein, the term “including” indicates the existence of the features, integers, steps, operations, elements, and/or components, but does not exclude the existence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups of the foregoing.
Unless otherwise defined, all terms used herein (including technical terms and scientific terms) have the same meanings as those commonly understood by those of ordinary in the art of the present disclosure. It is also to be understood that the terms used herein shall be interpreted as having the same meaning as they have in the specification and related fields, and shall not be interpreted in an idealized or overly formal sense, unless they have been explicitly defined herein.
In an aspect of the embodiments of the present disclosure, a manufacturing method for a single crystal film bulk acoustic resonator is provided. As shown in
At S010: a temporary base substrate is provided.
As shown in
At S020: a buffer layer, a piezoelectric layer, and a first electrode that are stacked are formed on the temporary base substrate sequentially.
As shown in
At S030: a first bonding layer is formed on the first electrode.
As shown in
At S040: a substrate is provided.
As shown in
At S050: the substrate is etched to form a plurality of first bumps on a surface of the substrate.
As shown in
It is to be understood that a method for etching the substrate 401 to form the first bumps and the etched grooves 406 may be a method of etching through a mask. For example, a whole layer of dielectric layer may be deposited on the surface of substrate 401, the dielectric layer is coated with a photoresist layer, and the dielectric layer may be patterned by the processes such as exposure, development, and etching. Then, the exposed substrate 401 may be etched to form the etched grooves 406 while correspondingly forming the first bumps at the same time. For another example, the surface of the substrate 401 may be directly coated with the photoresist layer, and the photoresist layer may be patterned through the processes such as exposure and development. Then, the exposed substrate 401 may be etched to form the etched groove 406 while correspondingly forming the first bumps at the same time.
At S060: a second bonding layer covering top surfaces of the plurality of first bumps is formed on the surface of the substrate.
As shown in
S070: the second bonding layer located at the top surfaces of the plurality of first bumps is bonded to the first bonding layer.
As shown in
During bonding, the area of the top surface of the first bump may be controlled by the etched groove 406, so that the area of the second bonding layer 507 located at the top surface of the first bump can be controlled, thereby controlling the bonding area. Through the flexible adjustment of the bonding area, a hierarchical structure on the temporary base substrate 101 and a hierarchical structure on the substrate 401 are prevented from being difficult to apply in mass production due to excessive bonding area, high bonding requirement, and high preparation cost on the basis of meeting the requirements of the bonding reliability. In other words, the present disclosure realizes the balance between the bonding requirement and the bonding reliability by controlling the bonding area.
At S080: the temporary base substrate is removed.
As shown in
At S090: the buffer layer is etched to form a first groove that exposes the piezoelectric layer.
As shown in
S100: a second electrode that is in contact with the piezoelectric layer is formed through the first groove.
As shown in
Optionally, after the first bonding layer is formed on the first electrode 204 through S030, the method further includes that: as shown in
Optionally, as shown in
In some implementation modes, the extraction electrode 911 and the second electrode may be formed at one step. For example, as shown in
Optionally, as shown in
As shown in
As shown in
As shown in
As shown in
A release hole is formed in the substrate 401, and the sacrificial layer is removed through the release hole to form a cavity.
The substrate 401 is aligned with the temporary base substrate 101, and then is bonded in a vacuum environment at 260° C. to 400° C. By controlling the height of the first bump to be equal to the compressed height during bonding, after the bonding is ended, the third groove 907 is just filled by gold, so as to achieve an overall bonding effect. In this way, since there is cavity structure in the device, a laminated structure below the third groove 907 is directly supported by the filled first bonding layer 307. When the temporary base substrate 101 is etched, the device will not deform due to pressure difference between the third groove 907 and the external environment, which avoids the deterioration of the device performance that may be caused by deformation. In addition, the etched parts of the first groove 809 and the second groove 808 are also be supported by the first bonding layer in the grooves, so a cracking phenomenon during etching can be avoided, thereby improving the quality of etching.
In another aspect of the embodiments of the present disclosure, a single crystal film bulk acoustic resonator 1002 is provided, which includes single crystal film bulk acoustic resonators 1002 prepared by any of the abovementioned manufacturing method for a single crystal film bulk acoustic resonator 1002. Specifically, as shown in
During bonding, the area of the top surface of the first bump may be controlled by the etched groove 406, so that the area of the second bonding layer 507 located at the top surface of the first bump can be controlled, thereby controlling the bonding area. Through the flexible adjustment of the bonding area, a hierarchical structure on the temporary base substrate 101 and a hierarchical structure on the substrate 401 are prevented from being difficult to apply in mass production due to excessive bonding area, high bonding requirement, and high preparation cost on the basis of meeting the requirements of the bonding reliability. In other words, the present disclosure realizes the balance between the bonding requirement and the bonding reliability by controlling the bonding area.
Optionally, both the first bonding layer and the second bonding layer 507 are metal layers, for example, gold layers. Since both the first bonding layer and the second bonding layer 507 are metal layers, the parasitic capacitance of the part can be effectively avoided, and the performance of a device can be improved. Of course, the first bonding layer 307 and the second bonding layer 507 may also be made of the same material.
In yet another aspect of the embodiments of the present disclosure, a filter is provided, as shown in
In some implementation modes, the first sealing ring and the foregoing second bonding layer 507 may be formed at the same step (a reference conductive layer including an extraction electrode 911 and a second electrode 910). Similarly, the second sealing ring and the foregoing first bonding layer may be formed at the same step (the reference conductive layer including the extraction electrode 911 and the second electrode 910).
Optionally, as shown in
In some implementation modes, the first sealing ring and the third sealing ring may be formed at single crystal film bulk acoustic resonator step. Similarly, the second sealing ring and the fourth sealing ring may be formed at single crystal film bulk acoustic resonator step.
Optionally, as shown in
Referring to
As shown in
In some implementation modes, the first sealing ring and the fifth sealing ring may be formed at the same step. Similarly, the second sealing ring and the sixth sealing ring may be formed at the same step.
The above is only the preferred embodiments of the present disclosure, and is not intended to limit the present disclosure. For those skilled in the art, the present disclosure may have various changes and variations. Any modifications, equivalent replacements, improvements and the like made within the spirit and principle of the present disclosure shall fall within the scope of protection of the present disclosure.
Number | Date | Country | Kind |
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202210027314.5 | Jan 2022 | CN | national |