CN115714587A - Filter and preparation method thereof - Google Patents

Abstract

The application provides a filter and a preparation method of the filter. The filter includes: a substrate, at least one resonator and at least one connection point located on the substrate; the resonator comprises a lamination of a lower electrode, a piezoelectric layer and an upper electrode, and at least one resonator further comprises an adjusting structure, wherein the adjusting structure is positioned on one side of the lower electrode of the resonator, which is far away from the substrate; the connecting point comprises a first conducting layer and a conducting structure, the conducting structure comprises at least one of a second conducting layer and a third conducting layer, the piezoelectric layer comprises a first through groove, and the first through groove is used for exposing the first conducting layer; the first conducting layer and the lower electrode are located on the same layer, the second conducting layer and the upper electrode are located on the same layer, and the third conducting layer and the adjusting structure are located on the same layer. The technical scheme provided by the application reduces the etching difficulty of the piezoelectric layer, increases the series resistance of the connecting points, and avoids the waste of materials caused by removing the part covering the connecting points in the patterning process of the conductive film layer of the resonator.

Description

Filter and preparation method thereof

Technical Field

The present disclosure relates to the field of semiconductor technologies, and in particular, to a filter and a method for manufacturing the filter.

Background

The filter formed by the film bulk acoustic resonator has the advantages of small size, high resonant frequency, high quality factor and the like, and is more and more widely applied in the field of communication.

Factors influencing the quality factor of the resonance point in the resonator (referred to as the Qs value of the resonance point) include the elastic loss of the piezoelectric layer, the elastic loss of the electrodes, the series resistance of the electrodes, and the like, and factors influencing the quality factor of the anti-resonance point in the resonator (referred to as the Qp value of the anti-resonance point) include the elastic loss of the piezoelectric layer, the elastic loss of the electrodes, the conductance of the substrate, the dielectric loss of the piezoelectric layer, and the like, wherein the series resistance of the lower electrode greatly influences the quality factor.

Referring to fig. 1, fig. 1 is a schematic structural diagram of a filter in the prior art, the filter includes a substrate 1, and a resonator 2 and a connection point 3 located on a surface of the substrate 1, the resonator 2 includes a stack of a lower electrode 20, a piezoelectric layer 21, and an upper electrode 22, the connection point 3 includes a first conductive layer 30, the first conductive layer 30 and the lower electrode 20 are located on the same layer, and the meaning that the first conductive layer 30 and the lower electrode 20 are located on the same layer is: the first conductive layer 30 and the lower electrode 20 are prepared by patterning the same conductive film layer. The piezoelectric layer 21 is provided with a first through groove 210 exposing the connection point 3, and the conductive bonding layer 4 covers the connection point 3, thereby leading out an electrical signal of the resonator 2. Wherein the resonator 2 includes a left resonator 2a and a right resonator 2b, the left resonator 2a further includes an adjusting structure 23, the adjusting structure 23 includes a mass loading layer 230 and a microstructure 231, and the microstructure 231 is a convex structure in this example. The right-hand resonator 2b comprises only a stack of a lower electrode 20, a piezoelectric layer 21 and an upper electrode 22. The cavity structure 1a of the substrate 1 in fig. 1 is made by adding an etching solution to the release holes after etching the sacrificial layer in the cavity structure 1a.

Since the connection point 3 only comprises the first conductive layer 30 at the same level as the lower electrode 20, the prior art has the following drawbacks: in the first aspect, in the process of etching the piezoelectric layer 21 to expose the connection point 3, the first conductive layer 30 is easily over-etched, which causes an increase in the series resistance of the connection point 3, resulting in deterioration of the value of the resonance point Qs. In the second aspect, when the frequency of the resonator is 5ghz or more, if the film thickness of the lower electrode is 100nm or less, the film thickness of the first conductive layer 30 is also 100nm or less, so that the thickness of the connection point 3 is relatively small, and the series resistance of the connection point 3 is too large, further causing deterioration of the value of the resonance point Qs. In the third aspect, the other conductive film layers in the resonator 2 are removed from the portion (e.g. the upper electrode 22 and the adjustment structure 23 in the left resonator 2a or the upper electrode 22 in the right resonator 2 a) covering the connection point 3 during the patterning process, resulting in a waste of material.

Disclosure of Invention

The application provides a filter and a preparation method of the filter, so that the etching difficulty of a piezoelectric layer is reduced, the series resistance of a connection point is increased, and the waste of materials caused by removing a part covering the connection point in the patterning process of a conductive film layer of a resonator is avoided.

The application provides a filter, including:

a substrate;

at least one resonator and at least one connection point located on the substrate;

the resonator comprises a lamination of a lower electrode, a piezoelectric layer and an upper electrode, and at least one of the resonators further comprises an adjusting structure, wherein the adjusting structure is positioned on one side, away from the substrate, of the lower electrode of the resonator;

the connection point comprises a first conductive layer and a conductive structure, the conductive structure comprises at least one of a second conductive layer and a third conductive layer, the piezoelectric layer comprises a first through groove, the first through groove is used for exposing the first conductive layer, and the conductive structure is arranged in the first through groove; the first conducting layer and the lower electrode are located on the same layer, an orthographic projection of the first conducting layer on the substrate covers an orthographic projection of the first through groove on the substrate, the second conducting layer and the upper electrode are located on the same layer, the third conducting layer and the adjusting structure are located on the same layer, the connecting point is connected with the upper electrode or the lower electrode, and the connecting point is used for leading out an electric signal of the resonator.

Optionally, the tuning structure comprises at least one of a microstructure and a mass-loading layer;

the third conductive layer comprises at least one of a first conductive sublayer and a second conductive sublayer, the first conductive sublayer and the microstructure are located on the same layer, and the second conductive sublayer and the mass loading layer are located on the same layer.

Optionally, the resonator includes an effective resonance region, the at least one resonator includes a first resonator, an upper electrode of the first resonator includes an electrical connection side and a non-electrical connection side, the electrical connection side is connected with the connection point, and the non-electrical connection side is insulated from the connection point;

the non-electrical connection side is located within the effective resonance region in an orthographic projection of the substrate.

Optionally, an included angle between the side surface and the bottom surface of the first through groove is greater than 90 °.

Optionally, the at least one connection point comprises a first connection point, a second connection point, and a third connection point;

the at least one resonator comprises a second resonator, a third resonator and a fourth resonator;

the first connection point is connected with a lower electrode of the second resonator;

the second connecting point is connected with an upper electrode of the second resonator, and the second connecting point is connected with a lower electrode of the third resonator;

the third connection point is connected to an upper electrode of the fourth resonator.

Optionally, the filter further comprises an electrically conductive bonding layer and a cover plate;

the conductive bonding layer covers the first connection point and the third connection point; or the conductive bonding layer covers the first connection point, the second connection point and the third connection point;

the cover plate is positioned on one side, far away from the substrate, of the conductive bonding layer, a conductive connection structure is arranged on one side, far away from the substrate, of the cover plate, and the conductive connection structure is connected with the conductive bonding layer through a conductive through hole structure positioned on the cover plate.

Optionally, the filter further comprises a sealing structure located between the substrate and the cover plate, disposed around the resonator and the connection point.

Optionally, the sealing structure includes a first sealing portion and a second sealing portion, the first sealing portion includes a first sealing sublayer and a sealing substructure, the sealing substructure includes at least one of a second sealing sublayer and a third sealing sublayer, the piezoelectric layer further includes a second through groove, the second through groove is used for exposing the first sealing sublayer, and the sealing substructure is disposed in the second through groove; the first sealing sublayer and the lower electrode are located on the same layer, an orthographic projection of the first sealing sublayer on the substrate covers an orthographic projection of the second through groove on the substrate, the second sealing sublayer and the upper electrode are located on the same layer, and the third sealing sublayer and the adjusting structure are located on the same layer; the second sealing part and the conductive bonding layer are located on the same layer.

The application also provides a preparation method of the filter, which comprises the following steps:

providing a substrate;

forming at least one resonator and at least one connection point on the substrate;

the resonator comprises a lamination of a lower electrode, a piezoelectric layer and an upper electrode, and at least one resonator further comprises an adjusting structure, wherein the adjusting structure is positioned on one side, away from the substrate, of the lower electrode of the resonator;

the connection point comprises a first conducting layer and a conducting structure, the conducting structure comprises at least one of a second conducting layer and a third conducting layer, the piezoelectric layer comprises a first through groove, the first through groove is used for exposing the first conducting layer, and the conducting structure is arranged in the first through groove; the first conducting layer and the lower electrode are located on the same layer, an orthographic projection of the first conducting layer on the substrate covers an orthographic projection of the first through groove on the substrate, the second conducting layer and the upper electrode are located on the same layer, the third conducting layer and the adjusting structure are located on the same layer, the connecting point is connected with the upper electrode or the lower electrode, and the connecting point is used for leading out an electric signal of the resonator.

Optionally, forming at least one resonator and at least one connection point on a surface of the substrate comprises:

forming a lower electrode and a first conducting layer on the surface of the substrate, wherein the lower electrode and the first conducting layer are positioned on the same layer;

forming a piezoelectric layer on a side of the lower electrode away from the substrate;

forming a first through groove in the piezoelectric layer, wherein the first through groove is used for exposing the first conducting layer, and an orthographic projection of the first conducting layer on the substrate covers the orthographic projection of the first through groove on the substrate;

forming an upper electrode on one side of the piezoelectric layer, which is far away from the lower electrode, forming a second conducting layer in the first through groove, wherein the upper electrode and the second conducting layer are positioned on the same layer;

and forming an adjusting structure on one side of the lower electrode, which is far away from the substrate, and forming a third conducting layer on the first through groove.

The technical scheme that this application provided, when graphical piezoelectric layer, expose first logical groove in the piezoelectric layer formation to the realization utilizes first logical groove to be used for injecing the shared space of tie point. The resonator includes the lamination of bottom electrode, piezoelectric layer and top electrode, and in a plurality of resonators, at least one resonator still includes the adjustment structure, and the connecting point includes first conducting layer (being located the same layer with the bottom electrode) and conducting structure, and conducting structure includes at least one in second conducting layer (being located the same layer with the top electrode) and third conducting layer (being located the same layer with the adjustment structure), and the connecting point still includes at least one in second conducting layer and third conducting layer in addition to including first conducting layer, compares prior art scheme, and the film number and the overall thickness of the conducting layer of this application's connecting point have been increased to the technical scheme of this application, adopt the advantage of this scheme to lie in:

in the first aspect, the number of the film layers of the conductive layers of the connecting points and the total thickness are increased, the series resistance of the connecting points can be reduced, the piezoelectric layer can be etched to form a first through groove, compensation is made for the increase of the series resistance of the connecting points due to the over-etching of the piezoelectric layer, the performance of a resonator cannot be affected even if the over-etching of the piezoelectric layer is carried out, the etching difficulty of the piezoelectric layer is reduced, meanwhile, the deterioration of the Qs value of the resonance point due to the increase of the series resistance of the connecting points is avoided, and the Qs value of the resonance point is improved.

In a second aspect, when the frequency of the resonator is greater than or equal to 5GHz, the film thickness of the lower electrode is less than or equal to 100nm, the film thickness of the first conductive layer is also less than or equal to 100nm, and the number of the film layers of the conductive layers of the connection point and the total thickness are increased, so that the series resistance of the connection point can be reduced, and the problem that the series resistance of the connection point is too large due to the fact that the film thickness of the first conductive layer is too thin, and the value of the resonance point Qs is deteriorated is solved.

In the third aspect, the connecting points are covered with the second conducting layer which is positioned on the same layer as the upper electrode and at least one layer of the third conducting layer which is positioned on the same layer as the adjusting structure, so that the problem that materials of the film layer at the connecting points are completely removed in the patterning process is avoided, and the material waste problem does not exist.

It should be understood that the statements in this section do not necessarily identify key or critical features of the embodiments of the present application, nor do they limit the scope of the present application. Other features of the present application will become apparent from the following description.

Drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed to be used in the description of the embodiments are briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present application, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without creative efforts.

FIG. 1 is a schematic diagram of a filter in the prior art;

fig. 2 is a schematic structural diagram of a filter provided in the present application;

FIG. 3 is a schematic diagram of another filter structure provided in the present application;

FIG. 4 is a top view of a filter provided herein;

fig. 5 is a schematic flow chart of a method for manufacturing a filter provided in the present application;

fig. 6 is a schematic structural diagram corresponding to S110 in fig. 5;

FIG. 7 is a schematic flow chart of S120 in FIG. 5

Fig. 8-14 are schematic structural diagrams corresponding to steps S120 in fig. 7.

Detailed Description

In order to make the technical solutions better understood by those skilled in the art, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are only partial embodiments of the present application, but not all embodiments. All other embodiments obtained by a person of ordinary skill in the art based on the embodiments in the present application without making any creative effort shall fall within the protection scope of the present application.

It should be noted that the terms "first," "second," and the like in the description and claims of this application and in the drawings described above are used for distinguishing between similar elements and not necessarily for describing a particular sequential or chronological order. It should be understood that the data so used may be interchanged under appropriate circumstances such that embodiments of the application described herein may be implemented in sequences other than those illustrated or described herein. Moreover, the terms "comprises," "comprising," and any other variation 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 acts is not necessarily limited to those steps or acts explicitly listed, but may include other steps or acts not expressly listed or inherent to such process, method, article, or apparatus.

In order to reduce the etching difficulty of the piezoelectric layer, increase the series resistance of the connection point and avoid the waste of materials caused by removing the part covering the connection point in the patterning process of the conductive film layer of the resonator, the application provides a new technical scheme, and the following detailed description is carried out.

Referring to fig. 2, fig. 2 is a schematic structural diagram of a filter provided in the present application, where the filter includes: a substrate 1 and at least one resonator 2 and at least one connection point 3 located at the surface of the substrate 1.

The resonator 2 comprises a stack of a lower electrode 20, a piezoelectric layer 21 and an upper electrode 22, and at least one of the resonators 2 further comprises an adjustment structure 23, the adjustment structure 23 being located on a side of the lower electrode 20 remote from the substrate 1.

The connection point 3 comprises a first conductive layer 30 and a conductive structure comprising at least one of a second conductive layer 31 and a third conductive layer 32. The piezoelectric layer 21 includes a first through groove 210, the first through groove 210 is used to expose the first conductive layer 30, and the conductive structure (i.e., at least one of the second conductive layer 31 and the third conductive layer 32) is disposed in the first through groove 210; the first conductive layer 30 and the lower electrode 20 are located on the same layer, an orthographic projection of the first conductive layer 30 on the substrate 1 covers an orthographic projection of the first through groove 210 on the substrate 1, the second conductive layer 31 and the upper electrode 22 are located on the same layer, the third conductive layer 32 and the adjusting structure 23 are located on the same layer, the connection point 3 is connected with the upper electrode 22 or the lower electrode 20, and the connection point 3 is used for leading out an electric signal of the resonator 2.

It should be noted that fig. 2 exemplarily shows two resonators 2, namely a left-side resonator 2c and a right-side resonator 2d, and the left-side resonator 2c includes a lower electrode 20, a piezoelectric layer 21, an upper electrode 22 and an adjustment structure 23. The right resonator 2d includes a lower electrode 20, a piezoelectric layer 21, and an upper electrode 22. In the design of the filter structure, it can be determined whether the adjustment structure 23 is provided in the resonator 2 or not, depending on the specific application needs. Further, the connection point 3 includes a first conductive layer 30, a second conductive layer 31, and a third conductive layer 32; the first conductive layer 30 and the lower electrode 20 are located at the same layer; the second conductive layer 31 and the upper electrode 22 are located on the same layer; the third conductive layer 32 and the adjustment structure 23 are located in the same layer.

In the present application, the meaning of being on the same layer is: the two film layers on the same layer are prepared by patterning the same conductive film layer. That is, the first conductive layer 30 and the lower electrode 20 are prepared by patterning the same conductive film layer, and the preparation of the first conductive layer 30 is completed while the lower electrode 20 is prepared. The second conductive layer 31 and the upper electrode 22 are prepared by patterning the same conductive film layer, and the preparation of the second conductive layer 31 is completed while the upper electrode 22 is prepared. The third conductive layer 32 and the adjustment structure 23 are prepared by patterning the same conductive film layer, and the preparation of the third conductive layer 32 is completed while the adjustment structure 23 is prepared.

According to the technical scheme, when the piezoelectric layer 21 is patterned, the first through groove 210 is exposed on the piezoelectric layer 21, so that the space occupied by the connecting point 3 is limited by the first through groove 210. The resonator 2 comprises a stack of a lower electrode 20, a piezoelectric layer 21 and an upper electrode 22, and among the plurality of resonators 2, at least one resonator 2 further comprises an adjustment structure 23, the connection point 3 comprises a first conductive layer 30 (located on the same layer as the lower electrode 20) and a conductive structure comprising at least one of a second conductive layer 31 (located on the same layer as the upper electrode 22) and a third conductive layer 32 (located on the same layer as the adjustment structure 23), i.e. the connection point 3 comprises at least one of the second conductive layer 31 and the third conductive layer 32 in addition to the first conductive layer 30, the technical solution of the present application increases the number of film layers and the overall thickness of the conductive layers of the connection point 3 compared to the prior art, and the advantage of the present solution is that:

in the first aspect, the number of the film layers of the conductive layer of the connection point 3 and the total thickness are increased, the series resistance of the connection point 3 can be reduced, compensation can be made for the increase of the series resistance of the connection point 3 caused by over-etching of the piezoelectric layer 21 in the process of etching the piezoelectric layer 21 into the first through groove 210, so that the performance of the resonator 2 cannot be affected even if the piezoelectric layer 21 is over-etched, the etching difficulty of the piezoelectric layer 21 is reduced, meanwhile, the deterioration of the value of the resonance point Qs caused by the increase of the series resistance of the connection point 3 is avoided, and the improvement of the value of the resonance point Qs is facilitated.

In a second aspect, when the frequency of the resonator is greater than or equal to 5GHz, the film thickness of the lower electrode 20 is less than or equal to 100nm, and the film thickness of the first conductive layer 30 is also less than or equal to 100nm, so that the number of the film layers of the conductive layer of the connection point 3 and the total thickness are increased, the series resistance of the connection point 3 can be reduced, and the problem of deterioration of the value of the resonance point Qs due to too large series resistance of the connection point 3 caused by too thin film thickness of the first conductive layer 30 is avoided.

In the third aspect, the connection point 3 is covered with at least one of the second conductive layer 31 and the third conductive layer 32, which are located in the same layer as the upper electrode 22 and the adjustment structure 23, so that the material of the film layer at the connection point 3 is completely removed in the patterning process, and the problem of material waste does not exist.

Optionally, on the basis of the above technical solution, as shown in fig. 2, the adjusting structure 23 includes at least one of a microstructure 231 and a mass loading layer 230, and the mass loading layer 230 is used for adjusting the frequency of the resonator; the microstructure 231 is used for inhibiting the leakage of the sound wave, and the microstructure 231 is provided with a convex structure and/or a concave structure; the third conductive layer 32 includes at least one of a first conductive sublayer 320 and a second conductive sublayer 321, the first conductive sublayer 320 and the microstructure 231 are located at the same layer, and the second conductive sublayer 321 and the mass loading layer 230 are located at the same layer.

Note that fig. 2 only shows a case where the microstructure 231 is provided with a projection structure. In other embodiments, the microstructures 231 may further include a concave structure, or the microstructures 231 includes both a convex structure and a concave structure, and the specific structure of the microstructures 231 may be set according to actual requirements.

In the present application, the adjusting structure 23 includes at least one of a microstructure 231 and a mass loading layer 230, the microstructure 231 is used to reduce the loss of the acoustic wave of the resonator 2, so as to improve the quality factor of the resonator 2, and the setting of the mass loading layer 230 is used to adjust the frequency of the resonator 2, so that the frequency of the resonator 2 meets a preset standard, which is set according to specific application requirements, such as: may be about 2496 Mhz. Moreover, the connection point 3 includes at least one of the first conductive sublayer 320 (and the microstructure 231 in the same layer) and the second conductive sublayer 321 (and the mass loading layer 230 in the same layer), which further increases the number of film layers and the overall thickness of the conductive layer of the connection point 3, thereby reducing the difficulty in etching the piezoelectric layer 21 and the series resistance of the connection point 3, and further avoiding the problem of material waste in the patterning process of at least one of the conductive film layer where the upper electrode 22 is located and the conductive film layer where the adjustment structure 23 is located.

Alternatively, on the basis of the above technical solution, as shown in fig. 2, the resonator 2 includes an effective resonance area, and the effective resonance area of the resonator 2 is an area where the lower electrode 20, the piezoelectric layer 21, the upper electrode 22 and the cavity structure 1a overlap in an orthographic projection of the substrate 1. The resonator 2 includes a first resonator, the upper electrode 22 of which includes an electrical connection side connected to the connection point 3 and a non-electrical connection side provided insulated from the connection point 3; the non-electrical connection side is located within the effective resonance region in the orthographic projection of the substrate 1.

Further, as shown in fig. 2, the resonator 2 includes a left side resonator 2c and a right side resonator 2d, both the left side resonator 2c and the right side resonator 2d can be used as first resonators, one side of the left side resonator 2c and the right side resonator 2d, where the upper electrode 22 is insulated from the connection point 3, is a non-electrical connection side, the non-electrical connection side is located in an effective resonance area in the orthographic projection of the substrate 1, and air is located outside the effective resonance area, so that the acoustic wave can be reflected back to the effective resonance area of the resonator 2, and further, the loss of the acoustic wave can be avoided, and thus, the quality factor of the resonator 2 is improved.

Optionally, on the basis of the above technical solution, as shown in fig. 2, an included angle between the side surface and the bottom surface of the first through groove 210 is greater than 90 °, that is, the first through groove 210 has a structure with a large top and a small bottom.

In this application, the side of first logical groove 210 is greater than 90 with the contained angle of bottom surface, compares the side of first logical groove 210 and the contained angle of bottom surface and is less than or equal to 90 the condition, and this scheme of adoption is convenient for the deposit of at least one deck in second conducting layer 31 and third conducting layer 32 in first logical groove 210 side, has improved the yield of the at least one deck in second conducting layer 31 and the third conducting layer 32 to the yield of tie point 3 has been improved.

Optionally, on the basis of the above technical solution, as shown in fig. 2, the connection point 3 includes a first connection point 3a, a second connection point 3b, and a third connection point 3c; the at least one resonator 2 includes a second resonator, a third resonator, and a fourth resonator; the first connection point 3a is connected to the lower electrode 20 of the second resonator; the second connection point 3b is connected to the upper electrode 22 of the second resonator, and the second connection point 3b is connected to the lower electrode 20 of the third resonator; the third connection point 3c is connected to the upper electrode 22 of the fourth resonator.

As shown in fig. 2, the resonator 2 includes a left-side resonator 2c and a right-side resonator 2d, the left-side resonator 2c serves as a second resonator, and the lower electrode 20 of the left-side resonator 2c is connected to the first conductive layer 30 of the first connection point 3a so that the first connection point 3a can lead out an electrical signal of the lower electrode 20 of the left-side resonator 2 c.

Further, the right resonator 2d functions as a third resonator, the second conductive layer 31 of the second connection point 3b is connected to the upper electrode 22 of the left resonator 2c, and the first conductive layer 30 of the second connection point 3b is connected to the lower electrode 20 of the right resonator 2c, so that the left resonator 2c and the right resonator 2d are connected in series through the second connection point 3 b. The second conductive layer 31 of the third connection point 3c is connected to the upper electrode 22 of the right resonator 2d so that the third connection point 3c can lead out the electrical signal of the upper electrode 22 of the right resonator 2 d.

Optionally, on the basis of the above technical solution, referring to fig. 3, fig. 3 is a schematic structural diagram of another filter provided in the present application, where the filter is similar to the embodiment shown in fig. 2, and the description of this embodiment for the same technical features is omitted here.

The filter further comprises an electrically conductive bonding layer 4 and a cover plate 5; the conductive bonding layer 4 covers the first connection point 3a and the third connection point 3c; alternatively, the conductive bonding layer 4 covers the first connection point 3a, the second connection point 3b and the third connection point 3c. The cover plate 5 is located on one side, far away from the substrate 1, of the conductive bonding layer 4, the conductive connection structure 6 is arranged on one side, far away from the substrate 1, of the cover plate 5, and the conductive connection structure 6 is connected with the conductive bonding layer 4 through the conductive through hole structure 7 located on the cover plate 5.

As shown in fig. 3, the connection point 3, the conductive bonding layer 4, the conductive via structure 7, and the conductive connection structure 6 lead out an electrical signal of the resonator 2 to the surface side of the lid plate 5 away from the substrate 1. The conductive bonding layer 4 in fig. 3 covers the first connection point 3a and the third connection point 3c. In other embodiments, the conductive bonding layer 4 may also cover the first connection point 3a, the second connection point 3b and the third connection point 3c. The specific position of the conductive bonding layer 4 can be set according to actual requirements.

Optionally, on the basis of the above technical solution, as shown in fig. 3, the filter further includes a sealing structure 8, where the sealing structure 8 is located between the substrate 1 and the cover plate 5, and the sealing structure 8 is disposed around the resonator 2 and the connection point 3. Optionally, the sealing structure includes a first sealing portion 80 and a second sealing portion 81, the first sealing portion 80 includes a first sealing sublayer 801 and a sealing substructure, the sealing substructure includes at least one of a second sealing sublayer 802 and a third sealing sublayer 803, the piezoelectric layer 21 further includes a second through groove 220, the second through groove 220 is used for exposing the first sealing sublayer 801, and the sealing substructure is disposed in the second through groove 220; the first sealing sublayer 801 and the lower electrode 20 are located on the same layer, an orthographic projection of the first sealing sublayer 801 on the substrate 1 covers an orthographic projection of the second through groove 220 on the substrate 1, the second sealing sublayer 802 and the upper electrode 22 are located on the same layer, and the third sealing sublayer 803 and the adjusting structure 23 are located on the same layer; the second sealing portion 81 and the conductive bonding layer 4 are located at the same layer.

Further, when the adjusting structure 23 includes at least one of the microstructure 231 and the mass loading layer 230, the third seal sublayer 803 includes at least one of a first portion of the third seal sublayer 8031 and a second portion of the third seal sublayer 8032, the first portion of the third seal sublayer 8031 and the microstructure 231 are located in the same layer, and the second portion of the third seal sublayer 8032 and the mass loading layer 230 are located in the same layer.

In the embodiment shown in fig. 3, the first sealing sub-layer 801 and the lower electrode 20 are located on the same layer, the second sealing sub-layer 802 and the upper electrode 22 are located on the same layer, the third sealing sub-layer 803 and the adjusting structure 23 are located on the same layer, and the second sealing portion 81 and the conductive bonding layer 4 are located on the same layer, which further saves the material waste of the conductive film layer and the conductive bonding layer 4 in the resonator 2, simplifies the manufacturing process, and reduces the manufacturing cost. Meanwhile, the sealing structure 8 provides a closed space for the resonator 2, so that the loss of sound waves is reduced, and the quality factor is improved.

Optionally, on the basis of the above technical solution, the materials of the upper electrode 22, the lower electrode 20 and the adjustment structure 23 are the same, for example, molybdenum metal may be selected; because the materials of the three conductive film layers (i.e. the upper electrode 22, the lower electrode 20 and the adjusting structure 23) are the same, and the materials of the conductive film layers at the connecting point 3 are also the same, the structural stability and firmness between the conductive layers of the connecting point 3 are increased, the problem of layering is not easy to occur, and the yield of the connecting point 3 is further improved.

Optionally, on the basis of the above technical solution, referring to fig. 4, fig. 4 is a top view of a filter provided in the present application, where a distance between the release hole T0 and the resonator 2 is relatively long, for example: the distance between the release hole T0 and the resonator 2 may be set to be more than 3 micrometers, which may prevent the release hole T0 from damaging the resonator 2, and may help to improve the yield of the resonator 2. In fig. 4, the leftmost connection point 3 is connected to the bottom electrode of the adjacent resonator 2.

Optionally, on the basis of the above technical solution, as shown in fig. 3, the resonator 2 further includes a passivation layer 24, and the passivation layer 24 is disposed on the upper electrode 22 and plays a role in protecting the resonator 2; the substrate 1 and the lower electrode 20 further comprise a seed layer 9 therebetween, and the material of the seed layer 9 is the same as that of the piezoelectric layer 21.

Based on the filter in the above embodiment, the application also provides a preparation method of the filter. Referring to fig. 5, fig. 5 is a schematic flow chart of a method for manufacturing a filter provided in the present application, and the method for manufacturing a filter is specifically described by taking the structure of the filter shown in fig. 2 as an example, and includes the following steps:

s110: a substrate is provided.

Referring to fig. 6, a photoresist is formed on the upper surface of the substrate 1 through a paste process, and then a groove structure is formed on the substrate 1 through exposure, development and etching processes, and a sacrificial material is formed in the groove structure through a deposition process, and then processed through a grinding process, to form a sacrificial layer 1b as shown in fig. 6.

It should be noted that the sacrificial layer 1b is provided to reduce the acoustic loss of the resonator 2, and the cavity structure 1a in the above embodiment can be formed after the sacrificial layer 1b is removed by an etching solution in a subsequent step. It is understood that, in addition to the cavity structure 1a as an acoustic reflection structure for reducing the acoustic wave loss of the resonator 2, other structures may be adopted, such as: a reflective layer is used which is formed by alternating high and low acoustic impedance materials, or alternatively, cavities are etched in the back of the substrate 1.

S120: at least one resonator and at least one connection point are formed on a substrate.

Referring to fig. 6, at least one resonator 2 and at least one connection point 3 are formed on a surface of a substrate 1, and an adjustment structure 23 is formed within the at least one resonator 2.

The resonator 2 comprises a stack of a lower electrode 20, a piezoelectric layer 21 and an upper electrode 22, and at least one of the resonators 2 further comprises an adjustment structure 23, the adjustment structure 23 being located on a side of the lower electrode 20 remote from the substrate 1.

The connection point 3 comprises a first conductive layer 30 and a conductive structure comprising at least one of a second conductive layer 31 and a third conductive layer 32. The piezoelectric layer 21 includes a first through groove 210, the first through groove 210 is used to expose the first conductive layer 30, and the conductive structure (i.e., at least one of the second conductive layer 31 and the third conductive layer 32) is disposed in the first through groove 210; the first conductive layer 30 and the lower electrode 20 are located on the same layer, an orthographic projection of the first conductive layer 30 on the substrate 1 covers an orthographic projection of the first through groove 210 on the substrate 1, the second conductive layer 31 and the upper electrode 22 are located on the same layer, the third conductive layer 32 and the adjusting structure 23 are located on the same layer, the connection point 3 is connected with the upper electrode 22 or the lower electrode 20, and the connection point 3 is used for leading out an electric signal of the resonator 2.

According to the technical scheme, when the piezoelectric layer 21 is patterned, the first through grooves 210 are exposed on the piezoelectric layer 21, so that the first through grooves 210 are used for limiting the space occupied by the connection points 3. The resonator 2 comprises a stack of a lower electrode 20, a piezoelectric layer 21 and an upper electrode 22, and of the plurality of resonators 2, at least one resonator 2 further comprises an adjustment structure 23, the connection point 3 comprises a first conductive layer 30 (on the same layer as the lower electrode 20) and a conductive structure comprising at least one of a second conductive layer 31 (on the same layer as the upper electrode 22) and a third conductive layer 32 (on the same layer as the adjustment structure 23), i.e. the connection point 3 comprises at least one of the second conductive layer 31 and the third conductive layer 32 in addition to the first conductive layer 30, which increases the number of film layers and the overall thickness of the conductive layers of the connection point 3 compared to the prior art, and the advantage of using this solution is that:

in the first aspect, the number of film layers of the conductive layer of the connection point 3 and the total thickness are increased, the series resistance of the connection point 3 can be reduced, compensation can be made for the increase of the series resistance of the connection point 3 caused by over-etching of the piezoelectric layer 21 in the process of etching the piezoelectric layer 21 into the first through groove 210, so that the performance of the resonator 2 cannot be affected even if the piezoelectric layer 21 is over-etched, the etching difficulty of the piezoelectric layer 21 is reduced, meanwhile, the deterioration of the Qs value of the resonance point caused by the increase of the series resistance of the connection point 3 is avoided, and the Qs value of the resonance point is improved.

In a second aspect, when the frequency of the resonator is greater than or equal to 5GHz, the film thickness of the lower electrode 20 is less than or equal to 100nm, and the film thickness of the first conductive layer 30 is also less than or equal to 100nm, so that the number of the conductive layers of the connection point 3 and the total thickness are increased, which can reduce the series resistance of the connection point 3, thereby avoiding the problem of deterioration of the value of the resonance point Qs due to too large series resistance of the connection point 3 caused by too thin film thickness of the first conductive layer 30.

In the third aspect, the connection point 3 is covered with at least one of the second conductive layer 31 and the third conductive layer 32, which are located in the same layer as the upper electrode 22 and the adjustment structure 23, so that the material of the film layer at the connection point 3 is prevented from being completely removed in the patterning process, and the problem of material waste is avoided.

In a specific embodiment, referring to fig. 7, fig. 7 is a schematic flow chart of step 120 in fig. 5, and based on the above technical solution, the step of forming at least one resonator and at least one connection point on the surface of the substrate includes:

s1201: a lower electrode and a first conductive layer are formed on a surface of a substrate.

Referring to fig. 8, a first conductive film layer is formed on the upper surface of the substrate 1 through a deposition process, a photoresist is formed on the surface of the first conductive film layer, and then the first conductive film layer is patterned through exposure, development and etching processes to form the lower electrode 20 and the first conductive layer 30, i.e., the lower electrode 20 and the first conductive layer 30 are located on the same layer.

S1202: a piezoelectric layer is formed on a side of the lower electrode away from the substrate.

Referring to fig. 9, a piezoelectric layer 21 is formed on the lower electrode 20 through a deposition process.

Further, in order to improve the film formation quality of the lower electrode 20 and the piezoelectric layer 21, the seed layer 9 is formed on the upper surface of the substrate 1 before the lower electrode 20 is formed, and the material of the seed layer 9 is the same as that of the piezoelectric layer 2.

S1203: a first through-trench is formed in the piezoelectric layer.

Referring to fig. 10, a photoresist is formed on an upper surface of the piezoelectric layer 21, and then a patterning process is performed on the piezoelectric layer 21 through an exposure, development and etching process to form first through grooves 210, the first through grooves 210 are used to expose the first conductive layer 30, and an orthographic projection of the first conductive layer 30 on the substrate 1 covers an orthographic projection of the first through grooves 210 on the substrate 1.

S1204: and forming an upper electrode on one side of the piezoelectric layer far away from the lower electrode, and forming a second conductive layer in the first through groove.

S1205: and forming an adjusting structure on one side of the lower electrode, which is far away from the substrate, and forming a third conductive layer on the first through groove.

Referring to fig. 11, a second conductive film layer is formed on a side of the lower electrode 20 away from the substrate 1, a photoresist is formed on an upper surface of the second conductive film layer, and then the second conductive film layer is patterned through exposure, development and etching processes to form a first conductive sublayer 320 and a microstructure 231, where the first conductive sublayer 320 and the microstructure 231 are located on the same layer.

Referring to fig. 12, a third conductive film layer is formed on a side of the piezoelectric layer 21 away from the lower electrode 20, a photoresist is formed on an upper surface of the third conductive film layer, and then the third conductive film layer is patterned through exposure, development and etching processes to form a second conductive layer 31 and an upper electrode 22 on the same layer, where the second conductive layer 31 is located above the first through groove 210.

Referring to fig. 13, a fourth conductive film layer is formed on a side of the upper electrode 22 away from the substrate 1, a photoresist is formed on an upper surface of the fourth conductive film layer, and then the fourth conductive film layer is patterned through exposure, development and etching processes to form a second conductive sublayer 321 and a mass loading layer 230 on the same layer.

Wherein the microstructure 231 and the mass loading layer 230 constitute the adjustment structure 23.

Referring to fig. 14, a passivation layer 24 is formed on the mass loading layer 230 and the upper electrode 22, and then an etching solution is applied into the release hole T0 shown in fig. 4, and the sacrificial layer 1b is etched away by the etching solution to form the cavity structure 1a shown in fig. 2.

It should be understood that various forms of the flows shown above, reordering, adding or deleting steps, may be used. For example, the steps described in the present application may be executed in parallel, sequentially, or in different orders, as long as the desired results of the technical solution of the present application can be achieved, and the present invention is not limited thereto.

The above-described embodiments should not be construed as limiting the scope of the present application. It should be understood by those skilled in the art that various modifications, combinations, sub-combinations and substitutions may be made in accordance with design requirements and other factors. Any modification, equivalent replacement, and improvement made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims (10)

1. A filter, comprising:

a substrate;

at least one resonator and at least one connection point located on the substrate;

the resonator comprises a lamination of a lower electrode, a piezoelectric layer and an upper electrode, and at least one of the resonators further comprises an adjusting structure, wherein the adjusting structure is positioned on one side, away from the substrate, of the lower electrode of the resonator;

the connection point comprises a first conducting layer and a conducting structure, the conducting structure comprises at least one of a second conducting layer and a third conducting layer, the piezoelectric layer comprises a first through groove, the first through groove is used for exposing the first conducting layer, and the conducting structure is arranged in the first through groove; the first conducting layer and the lower electrode are located on the same layer, an orthographic projection of the first conducting layer on the substrate covers an orthographic projection of the first through groove on the substrate, the second conducting layer and the upper electrode are located on the same layer, the third conducting layer and the adjusting structure are located on the same layer, the connecting point is connected with the upper electrode or the lower electrode, and the connecting point is used for leading out an electric signal of the resonator.

2. The filter of claim 1, wherein the tuning structure comprises at least one of a microstructure and a mass-loading layer;

the third conductive layer comprises at least one of a first conductive sublayer and a second conductive sublayer, the first conductive sublayer and the microstructure are located on the same layer, and the second conductive sublayer and the mass loading layer are located on the same layer.

3. The filter of claim 1, wherein the resonators include an effective resonance region, wherein the at least one resonator includes a first resonator, wherein an upper electrode of the first resonator includes an electrically connecting side and a non-electrically connecting side, wherein the electrically connecting side is connected to the connection point, and wherein the non-electrically connecting side is insulated from the connection point;

the non-electrical connection side is located within the effective resonance region in an orthographic projection of the substrate.

4. The filter of claim 1, wherein the side surfaces of the first through slot form an angle with the bottom surface greater than 90 °.

5. The filter of claim 1, wherein the at least one connection point comprises a first connection point, a second connection point, and a third connection point;

the at least one resonator comprises a second resonator, a third resonator and a fourth resonator;

the first connection point is connected with a lower electrode of the second resonator;

the second connection point is connected with the upper electrode of the second resonator, and the second connection point is connected with the lower electrode of the third resonator;

the third connection point is connected to an upper electrode of the fourth resonator.

6. The filter of claim 5, further comprising an electrically conductive bonding layer and a cover plate;

the conductive bonding layer covers the first connection point and the third connection point; or the conductive bonding layer covers the first connection point, the second connection point and the third connection point;

the cover plate is positioned on one side, far away from the substrate, of the conductive bonding layer, a conductive connection structure is arranged on one side, far away from the substrate, of the cover plate, and the conductive connection structure is connected with the conductive bonding layer through a conductive through hole structure positioned on the cover plate.

7. The filter of claim 6, further comprising an encapsulating structure positioned between the substrate and the cover plate, around the resonators and the connection points.

8. The filter of claim 7, wherein the sealing structure comprises a first sealing portion and a second sealing portion, the first sealing portion comprises a first sealing sublayer and a sealing substructure, the sealing substructure comprises at least one of a second sealing sublayer and a third sealing sublayer, the piezoelectric layer further comprises a second through slot, the second through slot is used for exposing the first sealing sublayer, and the sealing substructure is arranged in the second through slot; the first sealing sublayer and the lower electrode are located on the same layer, an orthographic projection of the first sealing sublayer on the substrate covers an orthographic projection of the second through groove on the substrate, the second sealing sublayer and the upper electrode are located on the same layer, and the third sealing sublayer and the adjusting structure are located on the same layer; the second sealing part and the conductive bonding layer are located on the same layer.

9. A method of making a filter, comprising:

providing a substrate;

forming at least one resonator and at least one connection point on the substrate;

the resonator comprises a lamination of a lower electrode, a piezoelectric layer and an upper electrode, and at least one of the resonators further comprises an adjusting structure, wherein the adjusting structure is positioned on one side, away from the substrate, of the lower electrode of the resonator;

the connection point comprises a first conducting layer and a conducting structure, the conducting structure comprises at least one of a second conducting layer and a third conducting layer, the piezoelectric layer comprises a first through groove, the first through groove is used for exposing the first conducting layer, and the conducting structure is arranged in the first through groove; the first conducting layer and the lower electrode are located on the same layer, an orthographic projection of the first conducting layer on the substrate covers an orthographic projection of the first through groove on the substrate, the second conducting layer and the upper electrode are located on the same layer, the third conducting layer and the adjusting structure are located on the same layer, the connecting point is connected with the upper electrode or the lower electrode, and the connecting point is used for leading out an electric signal of the resonator.

10. The method of claim 9, wherein forming at least one resonator and at least one connection point on a surface of the substrate comprises:

forming a lower electrode and a first conductive layer on the surface of the substrate, wherein the lower electrode and the first conductive layer are positioned on the same layer;

forming a piezoelectric layer on one side of the lower electrode far away from the substrate;

forming a first through groove in the piezoelectric layer, wherein the first through groove is used for exposing the first conducting layer, and the orthographic projection of the first conducting layer on the substrate covers the orthographic projection of the first through groove on the substrate;

forming an upper electrode on one side of the piezoelectric layer, which is far away from the lower electrode, forming a second conducting layer in the first through groove, wherein the upper electrode and the second conducting layer are located on the same layer;

and forming an adjusting structure on one side of the lower electrode, which is far away from the substrate, and forming a third conducting layer on the first through groove.

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