CN115483902A

CN115483902A - Resonator, resonator assembly, filter, and electronic device

Info

Publication number: CN115483902A
Application number: CN202110668062.XA
Authority: CN
Inventors: 李葱葱; 郝龙
Original assignee: ROFS Microsystem Tianjin Co Ltd
Current assignee: ROFS Microsystem Tianjin Co Ltd
Priority date: 2021-06-16
Filing date: 2021-06-16
Publication date: 2022-12-16

Abstract

The invention provides a resonator, a resonator assembly, a filter and an electronic device. The resonator includes a substrate; an acoustic mirror; a seed layer; a bottom electrode formed on the seed layer; a piezoelectric layer; and a top electrode; the overlapping parts of the acoustic mirror, the bottom electrode, the piezoelectric layer and the top electrode together form an effective area of the resonator; the area of the seed layer covering the active area in the transverse direction of the resonator is smaller than that of the active area, so that the effective electromechanical coupling coefficient of the resonator is adjusted by changing the area of the seed layer covering the active area. The invention can adjust parameters such as effective electromechanical coupling coefficient of the resonator by changing the area of the seed layer covering the effective area.

Description

Resonator, resonator assembly, filter, and electronic device

Technical Field

The present invention relates to the field of semiconductor technologies, and in particular, to a resonator, a resonator assembly, a filter, and an electronic device.

Background

With the development of modern wireless communication technology toward high frequency and high speed, filter devices such as filters and duplexers based on resonators, for example, film Bulk Acoustic Resonators (FBARs), are becoming more popular in the market.

The current filter generally includes a plurality of film bulk acoustic resonators. Each resonator includes a substrate, and film layers such as an acoustic mirror, a seed layer, a lower electrode, a piezoelectric layer, and an upper electrode, which are sequentially stacked on the substrate. The thickness ratios of the upper electrode, the lower electrode and the piezoelectric layer in the resonators determine the parameters of the resonators, and in the filter, each resonator may need to have different performance parameters.

However, in the conventional film bulk acoustic resonator, it is difficult to freely set and adjust the effective electromechanical coupling coefficient Kt without changing the thickness of each film layer in the resonator.

Disclosure of Invention

In view of the above problems, embodiments of the present application provide a resonator, a resonator assembly, a filter, and an electronic device, which are capable of adjusting an effective electromechanical coupling coefficient of the resonator.

In order to achieve the above object, a first aspect of the present application provides a resonator including a substrate; an acoustic mirror; a seed layer; a bottom electrode formed on the seed layer; a piezoelectric layer; and a top electrode; the overlapping parts of the acoustic mirror, the bottom electrode, the piezoelectric layer and the top electrode together form an effective area of the resonator; wherein the area of the seed layer covering the active area in the transverse direction of the resonator is smaller than the area of the active area, so as to adjust the effective electromechanical coupling coefficient of the resonator by changing the area of the seed layer covering the active area.

In an alternative embodiment, the seed layer covers at least a portion of the acoustic mirror; and the seed layer covers a part of the active area in the lateral direction of the resonator.

In an alternative embodiment, the ratio of the portion of the seed layer overlying the active area to the area of the active area is between 0.1 and 0.9.

In an alternative embodiment, the portion of the seed layer covering the active area is continuous.

In an alternative embodiment, the seed layer is in the shape of a hollow ring.

In an alternative embodiment the seed layer comprises at least two covers, with a spacing between different covers in the lateral direction of the resonator, and the covers and the active area have an overlap in the lateral direction of the resonator.

In an alternative embodiment, the cover and the active area partially overlap in the lateral direction of the resonator; alternatively, the cover is located entirely within the active area in the lateral direction of the resonator.

In an alternative embodiment, the different covers are all of uniform thickness in the transverse direction of the resonator.

In an alternative embodiment, the at least two cover portions comprise a first cover portion and a second cover portion, the second cover portion is in the shape of a hollow ring, the first cover portion is located in a region surrounded by the second cover portion, and the first cover portion is spaced from the inner side of the second cover portion.

In an alternative embodiment, the active area passes through the first cover part in the center of the resonator in the lateral direction.

In an alternative embodiment, the acoustic mirror comprises an air cavity.

In an alternative embodiment, the air cavities are formed by inward recessing of the substrate surface.

In an alternative embodiment, the air cavity is located on the side of the substrate surface facing the bottom electrode;

the resonator further comprises an interlayer electrode, the interlayer electrode is arranged on the substrate, the interlayer electrode and the seed layer are enclosed outside the air cavity together, and the interlayer electrode and the bottom electrode are mutually connected and conducted.

In an optional implementation manner, the air cavity further comprises an etching barrier layer, and the etching barrier layer is arranged on the interlayer electrode and is located in the air cavity.

In an alternative embodiment, the material of the seed layer includes at least one of aluminum nitride, zinc oxide, and lead zirconate titanate.

A second aspect of the application provides a resonator assembly comprising at least one resonator as described above, the seed layer in different resonators covering the active area in a different ratio of the area of the active area to the area of the active area in the lateral direction of the resonator.

A third aspect of the present application provides a filter comprising a resonator or resonator assembly as described above.

A fourth aspect of the present application provides an electronic device comprising the above-described filter.

The invention provides a resonator, a resonator assembly, a filter and an electronic device. The resonator includes a substrate; an acoustic mirror; a seed layer; a bottom electrode formed on the seed layer; a piezoelectric layer; and a top electrode; the overlapping parts of the acoustic mirror, the bottom electrode, the piezoelectric layer and the top electrode together form an effective area of the resonator; wherein the area of the seed layer covering the active area in the lateral direction of the resonator is smaller than the area of the active area, so as to adjust the effective electromechanical coupling coefficient Kt of the resonator by changing the area of the seed layer covering the active area. In the above solution, the area of the seed layer covering the active area in the lateral direction of the resonator is smaller than the area of the active area, so that in the active area of the resonator, a seed layer is formed in a part of the area, the bottom electrode in the part of the area can be deposited on the seed layer, and the crystal orientation is better; the bottom electrode in the other part of the area is directly deposited on the substrate, the crystal orientation is poor, so that the proportion of the better crystal orientation in the whole effective area is adjustable in the range of less than 1, and the resonator has an adjustable effective electromechanical coupling coefficient Kt so as to be beneficial to adjusting the performance of the filter. In other words, different Kt can be obtained by adjusting the area ratio of the portion of the seed layer covering the active region to the active region, and the degree of freedom of Kt can be selected. Therefore, the selection of the Kt freedom degree in the resonator is realized, the process is simple and easy to realize, and the effective area of the resonator is not required to be changed. The selectable range is wider, and the flexibility is higher.

The construction of the present invention and other objects and advantages thereof will be more apparent from the following description of the preferred embodiments taken in conjunction with the accompanying drawings.

Drawings

Fig. 1 is a schematic top view of a resonator provided in an embodiment of the present application;

FIG. 2 is A cross-sectional view taken along line A-O-A' of FIG. 1;

FIG. 3 is a comparison diagram of effective electromechanical coupling coefficients of a resonator without a seed layer and a resonator with a seed layer in the embodiment of the present application;

fig. 4 is a graph showing a relation between an area ratio of a seed layer occupying an effective region and an effective electromechanical coupling coefficient in a resonator according to an embodiment of the present application;

FIG. 5 is a schematic diagram of another structure of a resonator provided in an embodiment of the present application;

fig. 6 is a schematic diagram of still another structure of a resonator provided in an embodiment of the present application;

fig. 7 is a schematic diagram of another structure of a resonator provided in an embodiment of the present application;

FIG. 8 is a diagram illustrating another structure of a resonator according to an embodiment of the present application;

fig. 9 is a schematic diagram of another structure of a resonator according to an embodiment of the present application.

Description of reference numerals:

1-a substrate; 2. 2' -air cavity; 3-a bottom electrode; 4-a piezoelectric layer; 5-a top electrode; 6-a passivation layer; 7-sandwich electrodes; 10-etching the barrier layer; 8. 9-seed layer; 80. 90-a cover; 81. 91-a first cover; 82. 92-a second cover; 100. 100' -resonator.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all embodiments of the present invention. All other embodiments, which can be obtained by a person skilled in the art without making any creative effort based on the embodiments in the present invention, belong to the protection scope of the present invention.

The resonator is a common electronic device constituting a filter device such as a filter. The present resonator may include a thin film bulk acoustic resonator or the like. Taking a commonly used film bulk acoustic resonator as an example, it is specifically formed of a multilayer laminated structure. The multilayer laminated structure includes two oppositely disposed plate electrodes and a piezoelectric material disposed between the two plate electrodes. When voltage is applied to the plate electrode, the piezoelectric material can generate sound waves, and resonance is further formed.

However, parameters such as the effective electromechanical coupling coefficient kt of the film bulk acoustic resonator are determined by the thickness ratio of the electrode and the piezoelectric layer, so that kt between different resonators in the same filter design is difficult to freely adjust and set.

In the application, the area of the seed layer covering the effective region in the transverse direction of the resonator is smaller than that of the effective region, so that different effective electromechanical coupling coefficients Kt can be obtained by changing the area of the seed layer covering the effective region, the freedom degree of the resonator Kt is selected, and the performance of the filter is adjustable.

The resonator 100, the filter, and the electronic device according to the embodiment of the present application will be described below with reference to the drawings.

First, materials of respective layers in the resonator 100 appearing in the present application will be explained.

The material of the substrate 1 may be: the piezoelectric substrate 1 may be one of single crystal silicon, gallium nitride, gallium arsenide, sapphire, quartz, silicon carbide, and diamond, or may be a single crystal piezoelectric substrate 1 such as lithium niobate, lithium tantalate, or potassium niobate.

The acoustic mirror can be an air cavity, and a Bragg reflection layer and other equivalent forms can also be adopted.

The material of seed layer 8 may be: at least one of materials such as aluminum nitride (AlN), zinc oxide (ZnO), and single crystal lead zirconate titanate (PZT), or a rare earth element-doped material containing the above materials at a predetermined atomic ratio.

And the piezoelectric layer 4 may be: aluminum nitride, zinc oxide, single crystal lead zirconate titanate, and the like; the piezoelectric material may also be a rare earth element doped material containing a certain atomic ratio of the above materials.

The material of the top electrode 5 can be selected from molybdenum, ruthenium, gold, aluminum, magnesium, tungsten, copper, titanium, iridium, osmium, chromium or the compound of the above metals or the alloy thereof, etc.

The bottom electrode 3 may be made of the same material as the top electrode 5, and the material may be selected from molybdenum, ruthenium, gold, aluminum, magnesium, tungsten, copper, titanium, iridium, osmium, chromium, or a composite or alloy thereof of the above metals. The bottom electrode 3 and the top electrode 5 are typically the same material, but may be different.

The material of the interlayer electrode 7 can be selected from molybdenum, ruthenium, gold, aluminum, magnesium, tungsten, copper, titanium, iridium, osmium, chromium or the compound of the above metals or the alloy thereof, and the like.

The material of the passivation layer 6 may be silicon dioxide, aluminum nitride, silicon nitride or other kinds of dielectric materials.

The etching barrier layer 10 may be made of aluminum nitride, zinc oxide, single crystal lead zirconate titanate (PZT), or a rare earth element-doped material containing the above materials at a certain atomic ratio.

The specific structure and various possible implementations of the resonator are described in detail below with reference to specific embodiments. It should be noted that, in the present application, the vertical direction of the resonator refers to the stacking direction of the layers of the resonator, i.e., the thickness direction of the resonator, and the lateral direction of the resonator refers to a direction perpendicular to the vertical direction, e.g., the horizontal direction in fig. 2.

Fig. 1 is A schematic top view of A resonator provided in an embodiment of the present application, and fig. 2 is A cross-sectional view taken along A-O-A' in fig. 1.

Referring to fig. 1 and 2, the present invention provides a resonator 100 including a substrate 1, an acoustic mirror, a seed layer 8, a bottom electrode 3, a piezoelectric layer 4, and a top electrode 5. Wherein, optionally, the seed layer 8 may cover at least a part of the acoustic mirror; the bottom electrode 3 is formed on the seed layer 8. The overlapping parts of the acoustic mirror, the bottom electrode 3, the piezoelectric layer 4 and the top electrode 5 together form the active area of the resonator 100.

In other embodiments, the resonator 100 further includes a passivation layer 6 formed on the top electrode 5, and the passivation layer 6 covers the top electrode 5 to protect the top electrode 5.

Optionally, the substrate 1, the acoustic mirror, the seed layer 8, the bottom electrode 3, the piezoelectric layer 4, the top electrode 5, and the passivation layer 6 are sequentially stacked. And the area of the seed layer 8 covering the active area in the lateral direction of the resonator is smaller than the area of the active area.

In other words, in a possible case, the seed layer 8 covers a part of the active region in the lateral direction of the resonator 100, and in this case, it can be understood that the ratio of the area of the seed layer 8 covering the active region to the area of the active region is less than 1 and greater than 0; in another possible case, the seed layer 8 does not cover the active area in the lateral direction of the resonator 100, in which case the area of the seed layer 8 covering the active area is also smaller than the area of the active area, and in which case the ratio of the area of the seed layer 8 covering the active area to the area of the active area is 0. Note that, the case where the seed layer 8 does not cover the effective region in the lateral direction of the resonator 100 is considered to correspond to the case where the seed layer 8 does not exist in the resonator 100, that is, the bottom electrode 3 is disposed directly above the acoustic mirror.

Since the area of the seed layer 8 covering the active region in the lateral direction of the resonator 100 is always smaller than the area of the active region itself, in the embodiment of the present application, the effective electromechanical coupling coefficient Kt of the resonator can be adjusted by changing the area of the seed layer 8 covering the active region.

In the above scheme, before forming the electrode film layers such as the bottom electrode 3, the seed layer 8 is formed on the substrate 1, and the seed layer 8 can induce the crystal orientation growth of the electrode film layers such as the bottom electrode 3 in the vertical direction, so that the electrode film layers such as the bottom electrode 3 form a good crystal orientation, thereby improving the effective electromechanical coupling coefficient Kt of the resonator 100 to optimize the performance of the resonator 100.

The seed layer 8 covers at least part of the acoustic mirror means that the seed layer 8 can cover all the acoustic mirror and can also cover part of the acoustic mirror.

Here, the seed layer 8 may be formed by sputtering by PVD, for example, the seed layer 8 may be formed by PVD ALN on the substrate 1, so that the bottom electrode 3 may be deposited on the seed layer 8 by inducing growth of a crystal orientation in the bottom electrode 3 in a vertical direction, so that a better crystal orientation may be formed in the bottom electrode 3. Which in turn induces a better crystal growth in the piezoelectric layer 4 deposited on the bottom electrode 3, raising the effective electromechanical coupling coefficient kt of the resonator 100.

Fig. 3 is a comparison diagram of effective electromechanical coupling coefficients of a resonator without a seed layer and a resonator with a seed layer in the embodiment of the present application.

As can be understood from fig. 3, in the case where there is no seed layer in the resonator 100, the effective electromechanical coupling coefficient Kt of the resonator 100 is 7.9%, and in the case where the seed layer 8 is formed in the resonator 100, the effective electromechanical coupling coefficient Kt of the resonator 100 is 11.3%. From this, it is understood that the effective electromechanical coupling coefficient of the resonator 100 is improved in the case where the seed layer 8 is formed on the substrate 1.

In the embodiment of the present application, the seed layer 8 covers a part of the active region in the lateral direction of the resonator 100, which means that the active region and the seed layer 8 are projected on the substrate 1, and the projection of the active region and the projection of the seed layer 8 have an overlapping region. And the seed layer 8 does not cover the active area in its entirety in the lateral direction of the resonator 100, but only a part of the active area.

In the example of fig. 2, the portion of the seed layer 8 covering the active area is continuous.

It will be appreciated that the size of the active area covered by the seed layer 8 in the lateral direction of the resonator 100 may determine the size of the effective electromechanical coupling coefficient of the resonator 100. This is because the seed layer 8 directly induces the growth of the crystal orientation in the bottom electrode 3, and therefore the size of the seed layer 8 covering the active region directly determines how much region of the active region the crystal orientation is induced.

In other words, in the resonator 100, the portion having the seed layer 8 induces the crystal orientation growth of the electrode layer, and a good crystal orientation is formed in the electrode layer such as the bottom electrode 3 in the partial region; without the seed layer 8, the quality of the electrode layer such as the bottom electrode 3 directly deposited on the surface of the substrate 1 is not good, and the crystal orientation of the piezoelectric layer 4 is also not good. As described above, in the active region of the same resonator 100, the seed layer 8 is formed in a part of the region, and the bottom electrode 3 is deposited on the seed layer 8; the bottom electrode 3 is directly deposited on the substrate 1 in the other part of the region, so that different effective electromechanical coupling coefficients Kt are corresponding to different regions of the resonator 100, different Kt can be obtained by adjusting the area ratio of the seed layer 8 to the effective region of the resonator 100, and the selection of the degree of freedom of Kt is realized.

In the embodiment of the present application, if the selection of the Kt degree of freedom in the resonator 100 is realized by adjusting the area ratio of the portion of the seed layer covering the active region to the active region, the process is simple and easy to implement, and the active region of the resonator 100 does not need to be changed. Namely, the selectable range of the effective electromechanical coupling coefficient Kt can be adjusted according to the area ratio of the seed layer 8 relative to the effective area, the selectable range is wide, and the flexibility is high.

The area ratio of the portion of the seed layer covering the active region to the active region refers to the area ratio of the projected area of the portion of the seed layer covering the active region to the projected area of the active region, which is obtained by projecting the seed layer 8 and the active region on the substrate 1.

Optionally, the ratio of the area of the part of the seed layer covering the active region to the active region is between 0.1 and 0.9.

Fig. 4 is a graph showing a relationship between an area ratio of the seed layer occupying the active region and an effective electromechanical coupling coefficient in the resonator according to the embodiment of the present application. Referring to fig. 4, exemplarily, when the thicknesses of the top electrode 5, the bottom electrode 3 and the piezoelectric layer 4 are preset values, the effective electromechanical coupling coefficient Kt to the area ratio P of the seed layer occupying the effective area of the resonator follows the following formula:

the effective electromechanical coupling coefficient Kt =0.034 ×, the ratio P +0.079 of the area of the portion of the seed layer overlying the active region to the active region.

Experiments show that when the resonator 100 has no seed layer, that is, the area ratio of the seed layer to the effective area of the resonator 100 is 0, kt of the resonator 100 is the lowest; when the area ratio of the seed layer 8 to the active area of the resonator 100 is 1, the resonator 100 has the best performance, and Kt is the highest. When the area ratio of the seed layer 8 occupying the effective area of the resonator 100 is between 0 and 1, kt of the resonator 100 follows the above formula, whereby different Kt can be realized within the same resonator 100, and the desired Kt can be freely selected by the area ratio of the seed layer 8 occupying the effective area of the resonator 100.

Fig. 5 is a schematic diagram of another structure of a resonator provided in an embodiment of the present application, and fig. 6 is a schematic diagram of another structure of a resonator provided in an embodiment of the present application.

In the embodiment of the present application, the seed layer 8 may have a variety of different shapes, for example, the seed layer 8 may have a symmetric structure or an asymmetric structure, and the covering portion may also have a hollow or non-hollow structure.

Further, the seed layer 8 may be a single structure or a split structure composed of at least two separated portions. Fig. 5 illustrates another resonator cross-sectional structure when the seed layer 8 is a single structure, specifically, in some embodiments, the seed layer has a hollow ring shape, and the cross-section of the seed layer 8 has a discontinuous shape with a broken middle, as shown in fig. 5. It will be appreciated by those skilled in the art that seed layer 8 may take on other shapes than the seed layer 8 structure shown in fig. 1 and 5.

Referring to fig. 6, when the seed layer 8 has a split structure, at least two caps 80 may be included in the seed layer 8, different caps 80 having a spacing therebetween in the lateral direction of the resonator 100, and the caps 80 and the active region having an overlapping portion in the lateral direction of the resonator 100.

This includes both cases, one of which is that the cover 80 and the active area partly overlap in the lateral direction of the resonator 100, which means that at least part of the area on the cover 80 is outside the active area.

The other is that the cover 80 is located completely within the active area in the lateral direction of the resonator 100, which means that the projection of the cover 80 on the substrate 1 is located completely within the projection of the active area on the substrate 1.

It is noted that in some embodiments, the different covers 80 are of uniform thickness in the lateral direction of the resonator 100, for ease of deposition and to obtain a more stable effective electromechanical coupling coefficient. While in other embodiments the different covers 80 may also be of non-uniform thickness in the lateral direction of the resonator 100.

Alternatively, referring to fig. 6, the at least two covering parts 80 include a first covering part 81 and a second covering part 82, the second covering part 82 is in a hollow ring shape, the first covering part 81 is located in a region surrounded by the second covering part 82, and has a distance with the inner side of the second covering part 82. So that the first cover part 81 is in fact located in the area enclosed by the second cover part 82.

Alternatively, the center of the active area in the lateral direction of the resonator 100 passes through the first cover part 81. In this way, the effective electromechanical coupling coefficient Kt of the resonator 100 can be made higher with the same area ratio of the seed layer 8 to the effective region of the resonator 100.

In the embodiment of the present application, the acoustic mirror may include an air chamber 2. Here, the forming position of the air cavity 2 may be selected according to actual needs, and may be located in the substrate 1. As an alternative embodiment, referring to the resonator 100 shown in fig. 2, 5, and 6, the air cavity 2 is located in the substrate 1. The air cavities 2 are formed by inward depression of the surface of the substrate 1. In an actual process, the air cavity 2 may be formed by a sacrificial layer or the like.

The forming position of the air cavity 2 also includes the case of forming over the substrate 1, and fig. 7, 8, 9 are resonators 100 'in which the air cavity 2' is formed over the substrate 1. It should be noted that, regarding the resonator 100, the formation position of the resonator 100 'with respect to the air cavity' is improved, and a part of the film layer structure is added, and the rest part, for example, the seed layer covers a part of the active region in the lateral direction of the resonator, and the area ratio of the part of the seed layer covering the active region to the active region is between 0.1 and 0.9, which is the same as the resonator 100, and is not described herein again.

In the resonator 100', the degree of freedom kt in the resonator is also achieved by the ratio of the portion of the seed layer overlying the active region to the area of the active region. Moreover, the Chemical Mechanical Polishing (CMP) process is removed, so that the process can be optimized, the cost is saved, the impedance value of the resonator can be reduced, the effect of reducing the resistance of the high-frequency resonator is more obvious, and the performance of the resonator is effectively improved.

The structure of the resonator 100' is described in detail below.

Specifically, in the resonator 100', the air cavity 2' is located on the side of the surface of the substrate 1 facing the bottom electrode 3. And, resonator 100 'still includes intermediate layer electrode 7, and intermediate layer electrode 7 sets up on substrate 1, and intermediate layer electrode 7 and seed layer 9 enclose outside air cavity 2' jointly, and intermediate layer electrode 7 and bottom electrode 3 interconnect and conduct.

Optionally, the resonator 100 'further includes an etch stop layer 10, and the etch stop layer 10 may be disposed on the interlayer electrode 7 and located in the air cavity 2'. Wherein the etch stop layer 10 is used for the formation of the auxiliary air cavity 2'.

Specifically, referring to fig. 7, the seed layer 9 partially covers the air cavity 2', in this case, the seed layer 9 partially covers the active area, and the portion of the seed layer 9 covering the active area is continuous.

The seed layer 9 may be a single body or a separate body in the resonator 100' in accordance with various structures of the seed layer 8 in the resonator 100. Referring to fig. 8, as an alternative, the seed layer 9 has a hollow ring shape.

In another alternative, similar to the resonator 100, at least two covers 90 may be included in the seed layer 9, with a spacing between different covers 90 in the lateral direction of the resonator 100 'and with overlapping portions of the covers 90 and the active area in the lateral direction of the resonator 100'.

This includes both cases, one of which is that the cover 90 and the active area partly overlap in the lateral direction of the resonator 100', which means that at least part of the area on the cover 90 is located outside the active area.

The other is that the cover 90 is located completely within the active area in the lateral direction of the resonator 100', which means that the projection of the cover 90 onto the substrate 1 is located completely within the projection of the active area onto the substrate 1.

It is noted that for ease of deposition and to obtain a more stable effective electromechanical coupling coefficient, it is desirable to have the different covers 90 all have a uniform thickness in the lateral direction of the resonator 100'.

In the present application, the number of the covers 90 may be two or more, for example, and fig. 9 shows a case where the number of the covers 90 is two in the resonator 100.

Referring to fig. 9, as another alternative, the covering part 90 may include a first covering part 91 and a second covering part 92, the second covering part 92 has a hollow ring shape, the first covering part 91 is located in an area surrounded by the second covering part 92, and has a distance with the inner side of the second covering part 92. So that the first cover portion 91 is actually located in the area enclosed by the second cover portion 92.

Alternatively, the center of the active area in the lateral direction of the resonator 100' passes through the first cover part 91. Thus, the effective electromechanical coupling coefficient Kt of the resonator 100 'can be made higher with the same area ratio of the seed layer 8 to the effective region of the resonator 100'.

In an embodiment of the present application, a resonator includes a substrate; an acoustic mirror; a seed layer covering at least a portion of the acoustic mirror; a bottom electrode formed on the seed layer; a piezoelectric layer; a top electrode, and a passivation layer; the substrate, the acoustic mirror, the seed layer, the bottom electrode, the piezoelectric layer, the top electrode and the passivation layer are sequentially stacked, and the overlapped parts of the acoustic mirror, the bottom electrode, the piezoelectric layer and the top electrode form an effective area of the resonator together; wherein the seed layer covers a part of the active area in lateral directions of the resonator. In the scheme, different effective electromechanical coupling coefficients Kt can be obtained by adjusting the area ratio of the part of the seed layer covering the effective region to the effective region, and the selection of the degree of freedom Kt is realized. Therefore, the selection of the Kt freedom degree in the resonator is realized, the process is simple and easy to realize, and the effective area of the resonator is not required to be changed. The selectable range is wider, and the flexibility is higher.

It will be appreciated that the present application also provides a resonator assembly comprising at least one resonator as described in the above embodiments, the seed layer in the different resonators covering the active area in a different ratio to the area of the active area in the lateral direction of the resonator. Illustratively, the resonator assembly may include two resonators, and the seed layer in one resonator completely covers the active area, and the seed layer in the other resonator covers only a portion of the active area in the resonator lateral direction; alternatively, the resonator may also include two resonators, the seed layers of the two resonators both cover part of the active region, and the proportion of the area of the two resonators in which the seed layers cover the active region to the area of the corresponding active region is different. By analogy, the resonator component may further include more than two resonators, and the like, and the description of the case of more than two resonators is omitted here. It will be appreciated that the number of resonators in the resonator assembly, and the proportion of the area of the active area occupied by the seed layer in each resonator, may be set as desired.

As can be appreciated by those skilled in the art, the resonators 100, 100' according to the present invention may be used to form filters or electronic devices. Wherein the filter may be coupled or provided with other basic elements in addition to the resonators 100, 100' in the above-described embodiments. Specifically, the specific structure, function and main operation principle of the resonators 100 and 100' of the filter and the electronic device have been described in detail in the foregoing embodiments, and are not described herein again.

The electronic device comprises the filter, and the electronic device comprises but is not limited to intermediate products such as a radio frequency front end and a filtering amplification module, and terminal products such as a mobile phone, WIFI and an unmanned aerial vehicle.

In the present invention, the upper and lower are with respect to the bottom surface of the substrate of the resonator, and with respect to one component, the side thereof closer to the bottom surface is the lower side, and the side thereof farther from the bottom surface is the upper side.

In the present invention, the inner and outer are in the lateral or radial direction with respect to the center of the effective area of the resonator, the side or end of a component near the center being the inner or inner end, and the side or end of the component away from the center being the outer or outer end. For a reference position, inboard of the position means between the position and the center in the lateral or radial direction, and outboard of the position means farther from the center in the lateral or radial direction than the position.

In the description of the present invention, it should be noted that unless otherwise specifically stated or limited, the terms "mounted," "connected," and "connected" are to be construed broadly, e.g., as meaning a fixed connection, an indirect connection through intervening media, a connection between two elements, or an interaction between two elements. The specific meanings of the above terms in the present invention can be understood by those skilled in the art according to specific situations.

The terms "first," "second," "third," "fourth," and the like in the description and in the claims of the present application and in the drawings described above, if any, are used for distinguishing between similar elements and not necessarily for describing a particular sequential or chronological order. It is to be understood that the data so used is interchangeable under appropriate circumstances such that the embodiments of the application described herein are, for example, capable of operation in sequences other than those illustrated or otherwise described herein.

Furthermore, the terms "comprises," "comprising," and "having," and any variations thereof, are intended to cover a non-exclusive inclusion, such that a process, method, system, article, or apparatus that comprises a list of steps or elements is not necessarily limited to those steps or elements expressly listed, but may include other steps or elements not expressly listed or inherent to such process, method, article, or apparatus.

Finally, it should be noted that: the above embodiments are only used to illustrate the technical solution of the present invention, and not to limit the same; while the invention has been described in detail and with reference to the foregoing embodiments, it will be understood by those skilled in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some or all of the technical features may be equivalently replaced; and the modifications or the substitutions do not make the essence of the corresponding technical solutions depart from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A resonator, comprising:

a substrate;

an acoustic mirror;

a seed layer;

a bottom electrode formed on the seed layer;

a piezoelectric layer; and

a top electrode;

the overlapping portions of the acoustic mirror, the bottom electrode, the piezoelectric layer, and the top electrode collectively form an active area of the resonator;

the area of the seed layer covering the effective region in the transverse direction of the resonator is smaller than the area of the effective region, so that the effective electromechanical coupling coefficient of the resonator is adjusted by changing the area of the seed layer covering the effective region.

2. The resonator of claim 1, wherein the seed layer covers at least a portion of the acoustic mirror; and the seed layer covers part of the active area in the lateral direction of the resonator.

3. The resonator of claim 2, wherein a ratio of an area of a portion of the seed layer overlying the active area to the active area is between 0.1-0.9.

4. The resonator according to any of claims 1-3, characterized in that the part of the seed layer covering the active area is continuous.

5. The resonator of any of claims 1-3, wherein the seed layer is in the shape of a hollow ring.

6. A resonator according to any of claims 1-3, characterized in that the seed layer comprises at least two covers, with a distance between different covers in the transverse direction of the resonator, and that the covers and the active area have an overlapping part in the transverse direction of the resonator.

7. The resonator according to claim 6, characterized in that the cover and the active area partly overlap in a lateral direction of the resonator; alternatively, the cover is located entirely within the active area in a lateral direction of the resonator.

8. The resonator according to claim 6, characterized in that the different covers have a uniform thickness in the lateral direction of the resonator.

9. The resonator according to claim 6, wherein the at least two cover portions comprise a first cover portion and a second cover portion, the second cover portion being in the form of a hollow ring, the first cover portion being located in an area surrounded by the second cover portion and having a distance to an inner side of the second cover portion.

10. The resonator according to claim 9, characterized in that the active area passes the first cover part in the center of the resonator in the lateral direction.

11. The resonator of any of claims 1-3, wherein the acoustic mirror comprises an air cavity.

12. The resonator of claim 11, wherein the air cavities are formed by inward depression of the surface of the substrate.

13. The resonator of claim 11, wherein the air cavity is located on a side of the substrate surface facing the bottom electrode;

the resonator further comprises an interlayer electrode, the interlayer electrode is arranged on the substrate, the interlayer electrode and the seed layer surround the outer side of the air cavity together, and the interlayer electrode and the bottom electrode are mutually connected and conducted.

14. The resonator of claim 13, further comprising an etch stop layer disposed on the interlayer electrode and within the air cavity.

15. The resonator of claim 14, wherein the material of the seed layer comprises at least one of aluminum nitride, zinc oxide, and lead zirconate titanate.

16. A resonator assembly, characterized in that the resonator assembly comprises at least one resonator according to any of claims 1-15, and that the seed layer in different resonators has a different ratio of the area covering the active area to the area of the active area in the lateral direction of the resonator.

17. A filter comprising a resonator according to any of claims 1-15 or a resonator assembly according to claim 16.

18. An electronic device comprising the filter of claim 17.