阅读说明：本技术 滤波器及其制备方法、双工器 (Filter, preparation method thereof and duplexer ) 是由 吴明 王家友 王矿伟 杨清华 唐兆云 赖志国 李合景 于 2021-07-29 设计创作，主要内容包括：本发明实施例公开了一种滤波器及其制备方法、双工器,各谐振器层在衬底的一侧沿衬底厚度方向堆叠设置,各谐振器层形成垂直结构而非平铺结构,使得滤波器所占用平面的面积减小,提高滤波器的集成度,进而有利于实现包括本实施例的滤波器的通信系统的小型化。并且,本发明实施例的滤波器仅包括一个晶圆,进而使得滤波器中所需晶圆数量减少,有利于节约成本；且相邻谐振器层直接接触,因此直接在一谐振器层的一侧进行相邻谐振器层的沉积即可,无需采用键合工艺,使得滤波器的制备工艺也较为简化。(The embodiment of the invention discloses a filter, a preparation method thereof and a duplexer, wherein all resonator layers are stacked on one side of a substrate along the thickness direction of the substrate, and all the resonator layers form a vertical structure instead of a tiled structure, so that the area of a plane occupied by the filter is reduced, the integration level of the filter is improved, and the miniaturization of a communication system comprising the filter of the embodiment is further facilitated. In addition, the filter of the embodiment of the invention only comprises one wafer, so that the number of wafers required in the filter is reduced, and the cost is saved; and adjacent resonator layers are in direct contact, so that the deposition of the adjacent resonator layers is directly carried out on one side of one resonator layer without adopting a bonding process, and the preparation process of the filter is simplified.)

1. A filter, comprising:

a substrate;

the resonator layers are stacked on one side of the substrate along the thickness direction of the substrate and are in direct contact with the adjacent resonator layers.

2. The filter according to claim 1, wherein the resonator layers include a lower electrode layer, a piezoelectric layer, an upper electrode layer, and a cap layer, which are stacked, the lower electrode layer of the same resonator layer is located on a side of the upper electrode layer close to the substrate, and thicknesses of corresponding setting film layers of at least two resonator layers are different, and the setting film layer is at least one of the lower electrode layer, the upper electrode layer, and the piezoelectric layer.

3. The filter of claim 2,

a cavity is formed between the cap layer and the upper electrode layer of the same resonator layer;

the resonator layer comprises a plurality of resonators, each resonator comprises a lower electrode positioned on the lower electrode layer, a piezoelectric unit positioned on the piezoelectric layer and an upper electrode positioned on the upper electrode layer, and at least parts of the lower electrode, the piezoelectric unit and the upper electrode of each resonator are positioned in the cavity.

4. The filter of claim 3, wherein the cap layer is formed by deposition.

5. The filter of claim 3, wherein each resonator layer is provided with an acoustically reflective structure on a side thereof adjacent to the substrate, the acoustically reflective structure being located on the substrate or on the cap layer.

6. The filter of claim 2, wherein the same film layers of at least two of the resonators in the same resonator layer have different thicknesses.

7. A filter according to claim 3, characterised in that the thickness of the same film layer is the same for each resonator of the same resonator layer.

8. The filter of claim 3, further comprising conductive leads for connecting resonators located on different layers of the resonator; the conductive lead penetrates through at least one capping layer in the thickness direction of the filter.

9. A method of making a filter, comprising:

providing a substrate;

forming at least two resonator layers on one side of the substrate;

when an adjacent resonator layer is formed on one side, far away from the substrate, of one resonator layer, a film layer of the adjacent resonator layer is directly deposited on one side, far away from the substrate, of the one resonator layer, so that at least two resonator layers are stacked on one side of the substrate in the thickness direction of the substrate and are in direct contact with the adjacent resonator layers.

10. The method of claim 8, wherein forming at least two resonator layers on one side of the substrate comprises:

forming at least two resonator layers stacked in the thickness direction of the substrate on one side of the substrate layer by layer;

wherein forming any of the at least two resonator layers comprises:

sequentially forming a lower electrode layer, a piezoelectric layer and an upper electrode layer on one side of a set substrate;

depositing a sacrificial material on a side of the upper electrode layer away from the defined substrate;

patterning the sacrificial material to leave sacrificial material corresponding to locations where resonators are formed;

forming a cap layer on one side of the sacrificial material far away from the setting substrate;

patterning the cap layer to release the sacrificial material;

wherein the setting base is the substrate or the cap layer.

11. The method for manufacturing a filter according to claim 10, further comprising, before forming the lower electrode layer, the piezoelectric layer, and the upper electrode layer in this order on one side of the setting substrate:

and arranging an acoustic reflection structure in the setting substrate or on the surface of the setting substrate, wherein the lower electrode layer at least partially covers the acoustic reflection structure.

12. A duplexer comprising a transmit filter and a receive filter, the transmit filter and/or the receive filter being a filter according to any one of claims 1 to 8.

13. The duplexer of claim 12, wherein the transmit filter and the receive filter are bonded in a thickness direction of the substrate.

14. The duplexer of claim 13, further comprising a sealing ring located between the transmit filter and the receive filter, the transmit filter and the receive filter being bonded by the sealing ring.

15. The duplexer of claim 14, wherein the seal ring is disposed on a side of the transmit filter farthest from the resonator layer of the substrate of the transmit filter and on a side of the receive filter farthest from the resonator layer of the substrate of the receive filter, and wherein the resonator layer of the transmit filter farthest from the substrate of the transmit filter, the resonator layer of the receive filter farthest from the substrate of the receive filter, and the seal ring form a sealed structure.

Technical Field

The embodiment of the invention relates to the technical field of communication filters, in particular to a filter, a preparation method of the filter and a duplexer.

Background

With the development of communication technology, miniaturization of communication systems has become a major trend.

The application of the filter in a communication system is very wide, the existing filter generally includes a plurality of resonators, the distribution of the plurality of resonators in the existing filter includes two types, fig. 1 is a schematic structural diagram of a filter in the prior art, and referring to fig. 1, one of the distribution is that the plurality of resonators 30 are respectively disposed at different positions on the surface of the same substrate 10, that is, each resonator 30 is tiled on the surface of the substrate. The surface of the substrate 10 comprises a resonator layer 20, the resonator layer 20 comprises a lower electrode layer 21, a piezoelectric layer 22 and an upper electrode layer 23, wherein the upper electrode layer 23 comprises a plurality of upper electrodes 31, each resonator 30 can comprise at least one upper electrode 31, and the control of the mass loading layer thickness of the resonator is realized by arranging the upper electrodes 31 of different resonators to have different thicknesses, specifically, the part of the upper electrode 31 in the resonator with the upper electrode 31 with thicker thickness is thicker than the part of the upper electrode 31 in the resonator with the upper electrode 31 with thinner thickness is used as the mass loading layer of the resonator with thicker thickness. To realize different thicknesses of the upper electrodes 31 of different resonators, there are generally two ways to prepare the upper electrode layer 23, wherein one way is to deposit the material of the upper electrode layer 23 in multiple times, and the example is described with the upper electrodes 31 having three different thicknesses of all the resonators included in the filter. Specifically, a layer of upper electrode material having a first thickness may be deposited first on the side of the piezoelectric layer 22 away from the substrate 10, and the resonator having the thinnest upper electrode 31 in the filter may have the upper electrode 31 having the first thickness as its own upper electrode 31; then, continuously depositing an upper electrode material at a part of the first-thickness upper electrode material layer far away from the substrate 10 to form an upper electrode material layer with a second thickness, wherein the resonator of the filter with the upper electrode 31 with the middle thickness can use the upper electrode 31 with the second thickness as the upper electrode 31 of the resonator; then, the deposition of the upper electrode material is continued at the position of the upper electrode material layer with the second thickness far away from the substrate 10, so as to form an upper electrode material layer with a third thickness, and the resonator with the thickest upper electrode 31 in the filter can use the upper electrode 31 with the third thickness as the upper electrode 31 of the resonator. Another way to prepare the upper electrode layer 23 may be a way of depositing once and etching multiple times, specifically, a layer of an upper electrode material with a third thickness may be deposited first, and the resonator having the thickest upper electrode 31 in the filter may use the upper electrode 31 with the third thickness as its own upper electrode 31; then, etching a part of the upper electrode material layer with the third thickness to enable the upper electrode layer 23 material layer at the part of the filter to have a second thickness, wherein the resonator of the upper electrode 31 with the middle thickness in the filter can use the upper electrode 31 with the second thickness as the upper electrode 31 of the resonator; by etching the partial position of the upper electrode material layer with the second thickness, so that the upper electrode material layer with the partial position in the filter has the first thickness, the resonator with the thinnest upper electrode 31 in the filter can use the upper electrode 31 with the first thickness as the upper electrode 31 of the resonator. As can be seen from the above process of preparing the upper electrode layer 23, the prior art method for implementing the resonator in the filter to have the upper electrodes 31 with different thicknesses is complicated, and the mass loading layer formed by the above preparation method is equivalent to the mass loading layer connected to the upper electrode layer 23, and it is difficult to accurately measure the thickness of the mass loading layer. In addition, the distributed manner in which the resonators are tiled on the surface of the substrate 10 in the conventional filter makes the filter larger in size, which is not favorable for realizing miniaturization of a communication system.

Fig. 2 is a schematic structural diagram of another filter in the prior art, and referring to fig. 2, another way of distributing a part of the filter on one wafer (substrate 10) and a part of the filter on another wafer, and the two wafers are connected by bonding, and fig. 2 schematically shows two wafers, each wafer having one filter disposed thereon. Then, the above two wafer bonding method requires a large number of wafers, which results in high cost and complex process.

Disclosure of Invention

The invention provides a filter, a preparation method thereof and a duplexer, which are used for solving at least one problem in the prior art.

In a first aspect, an embodiment of the present invention provides a filter, including:

a substrate;

the resonator comprises at least two resonator layers, wherein each resonator layer is stacked on one side of the substrate along the thickness direction of the substrate, and adjacent resonator layers are in direct contact.

Optionally, the resonator layer includes a lower electrode layer, a piezoelectric layer, an upper electrode layer, and a cap layer, which are stacked, the lower electrode layer of the same resonator layer is located on one side of the upper electrode layer close to the substrate, thicknesses of corresponding setting film layers in at least two resonator layers are different, and the setting film layer is at least one of the lower electrode layer, the upper electrode layer, and the piezoelectric layer.

A cavity is formed between the cap layer and the upper electrode layer of the same resonator layer;

the resonator layer includes a plurality of resonators including a lower electrode on the lower electrode layer, a piezoelectric element on the piezoelectric layer, and an upper electrode on the upper electrode layer, at least portions of the lower electrode, the piezoelectric element, and the upper electrode of the resonators being located within the cavity.

Optionally, the cap layer is formed by deposition.

Optionally, one side of each resonator layer close to the substrate is provided with an acoustic reflection structure, and the acoustic reflection structure is located on the substrate or the cap layer.

Optionally, the thicknesses of the same film layers of at least two resonators in the same resonator layer are different.

Optionally, the thickness of the same film layer of each resonator of the same resonator layer is the same.

Optionally, the filter further includes a conductive lead for connecting resonators located in different resonator layers; the conductive lead penetrates through the at least one capping layer in the thickness direction of the filter.

In a second aspect, an embodiment of the present invention further provides a method for manufacturing a filter, including:

providing a substrate;

forming at least two resonator layers on one side of a substrate;

when the adjacent resonator layers are formed on one side, far away from the substrate, of one resonator layer, the film layers of the adjacent resonator layers are directly deposited on one side, far away from the substrate, of the one resonator layer, so that at least two resonator layers are stacked on one side of the substrate in the thickness direction of the substrate and are in direct contact with the adjacent resonator layers.

Optionally, forming at least two resonator layers on one side of the substrate includes:

forming at least two resonator layers stacked in the thickness direction of the substrate on one side of the substrate layer by layer;

wherein forming any one of at least two resonator layers comprises:

sequentially forming a lower electrode layer, a piezoelectric layer and an upper electrode layer on one side of a set substrate;

depositing a sacrificial material on one side of the upper electrode layer away from the setting substrate;

patterning the sacrificial material to leave sacrificial material corresponding to locations where the resonators are formed;

forming a cap layer on one side of the sacrificial material far away from the setting substrate;

patterning the cap layer to release the sacrificial material;

wherein the base is set as a substrate or a cap layer.

Optionally, before forming the lower electrode layer, the piezoelectric layer, and the upper electrode layer in sequence on one side of the setting substrate, the method further includes:

an acoustic reflection structure is arranged in the inner part or on the surface of the setting substrate, and the lower electrode layer at least partially covers the acoustic reflection structure.

In a third aspect, an embodiment of the present invention further provides a duplexer, including a transmit filter and a receive filter, where the transmit filter and/or the receive filter are/is the filter of the first aspect.

Optionally, the transmitting filter and the receiving filter are bonded in the thickness direction of the substrate.

Optionally, the duplexer further includes a sealing ring, the sealing ring is located between the transmitting filter and the receiving filter, and the transmitting filter and the receiving filter are connected by bonding the sealing ring.

Optionally, the sealing ring is disposed on a side of the substrate of the transmitting filter farthest from the substrate of the transmitting filter, and is disposed on a side of the substrate of the receiving filter farthest from the substrate of the receiving filter, and the resonator layer of the substrate of the transmitting filter farthest from the substrate of the transmitting filter, the resonator layer of the substrate of the receiving filter farthest from the substrate of the receiving filter, and the sealing ring form a sealing structure.

According to the filter, the preparation method thereof and the duplexer provided by the embodiment of the invention, the resonator layers are stacked on one side of the substrate along the thickness direction of the substrate, and the resonator layers form a vertical structure instead of a tiled structure, so that the area of a plane occupied by the filter is reduced, the integration level of the filter is improved, and the miniaturization of a communication system comprising the filter of the embodiment is further facilitated. In addition, the filter of the embodiment of the invention only comprises one wafer, so that the number of wafers required in the filter is reduced, and the cost is saved; and adjacent resonator layers are in direct contact, so that the deposition of the adjacent resonator layers is directly carried out on one side of one resonator layer without adopting a bonding process, and the preparation process of the filter is simplified.

Drawings

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

FIG. 2 is a schematic diagram of another prior art filter configuration;

fig. 3 is a schematic structural diagram of a filter according to an embodiment of the present invention;

FIG. 4 is a schematic diagram of another filter according to an embodiment of the present invention;

fig. 5 is a flowchart of a method for manufacturing a filter according to an embodiment of the present invention;

FIG. 6 is a flow chart of forming any of the resonator layers provided by embodiments of the present invention;

FIG. 7 is a schematic structural diagram of a substrate with an acoustic reflection structure formed on a surface of the substrate according to an embodiment of the present invention;

fig. 8 is a schematic structural diagram of a substrate provided in an embodiment of the present invention after sequentially forming a lower electrode layer, a piezoelectric layer, and an upper electrode layer on a surface of the substrate;

FIG. 9 is a schematic structural diagram of the structure after the sacrificial material between the upper electrode layer and the cap layer is released;

fig. 10 is a schematic structural diagram of a duplexer provided in an embodiment of the present invention;

fig. 11 is a schematic structural diagram of another duplexer provided in the embodiment of the present invention.

Detailed Description

The present invention will be described in further detail with reference to the accompanying drawings and examples. It is to be understood that the specific embodiments described herein are merely illustrative of the invention and are not limiting of the invention. It should be further noted that, for the convenience of description, only some of the structures related to the present invention are shown in the drawings, not all of the structures.

An embodiment of the present invention provides a filter, and fig. 3 is a schematic structural diagram of the filter provided in the embodiment of the present invention, and referring to fig. 3, the filter includes:

a substrate 110;

at least two resonator layers 120, each resonator layer 120 is stacked along the thickness direction y of the substrate 110 on one side of the substrate 110, and adjacent resonator layers 120 are in direct contact.

The material of the substrate 110 may be silicon, gallium arsenide, silicon carbide, gallium nitride, or a mixture of at least two of the above materials, which is not limited in this embodiment.

Referring to fig. 3, the filter further includes at least two resonator layers 120, and the resonator layers 120 are stacked on one side of the substrate 110 in a thickness direction y of the substrate 110. Optionally, it is required that each resonator layer 120 is stacked on one side of the substrate 110 in the thickness direction y of the substrate 110, and the vertical projections of each resonator layer 120 on the substrate 110 are at least partially overlapped; alternatively, the perpendicular projections of the resonator layers 120 onto the substrate 110 are completely coincident.

Compared with the structure that each resonator is tiled at one side of the substrate 110 in the prior art, in the embodiment, each resonator layer 120 is stacked at one side of the substrate 110 along the thickness direction y of the substrate 110, and each resonator layer 120 forms a vertical structure instead of a tiled structure, so that the area of the plane occupied by the filter is reduced, the integration level of the filter is improved, and further the miniaturization of the communication system including the filter of the embodiment is facilitated.

Compared with the filter structure in which the resonators are respectively arranged on the two wafers and the two wafers are bonded and connected in the prior art, the filter of the embodiment only includes one wafer (i.e., the substrate 110 in the embodiment), so that the number of wafers required in the filter is reduced, and cost saving is facilitated. In addition, when the resonator layers 120 are prepared on the substrate 110 in this embodiment, the resonator layers 120 may be formed by one layer on one side of the substrate 110 along the thickness direction y of the substrate 110, specifically, a first resonator layer is formed on one side of the substrate 110, a second resonator layer is formed on one side of the first resonator layer away from the substrate 110, and a third resonator layer is formed on one side of the second resonator layer away from the substrate 110; the multilayer resonator layer 120 may be formed as described above according to the number of resonator layers 120 that need to be included in the filter. Therefore, a bonding process is not needed, and the preparation process of the filter is simplified. In addition, in this embodiment, the resonator layers 120 are stacked on one side of the substrate 110 along the thickness direction y of the substrate 110, so that each layer of resonator layer 120 can be independently and precisely frequency-modified when being formed, and interference between different resonators in the frequency modification process can be avoided.

When any one of the resonator layers 120 is formed, the film layer structure included in the resonator layer 120 may be formed in a manner known in the art. Optionally, the resonator layer 120 includes a lower electrode layer, a piezoelectric layer, and an upper electrode layer, and when the lower electrode layer is formed, the lower electrode layer may be formed by depositing an entire layer of a lower electrode layer material, and then patterning the entire layer of the lower electrode material; when the piezoelectric layer is formed, the piezoelectric layer deposition is directly carried out on the side of the lower electrode layer far away from the substrate 110; when forming the upper electrode layer, an entire upper electrode material layer may be first deposited on the side of the piezoelectric layer away from the substrate 110, and then the entire upper electrode material layer may be patterned to form the upper electrode layer.

In this embodiment, adjacent resonator layers are in direct contact, that is, the adjacent resonator layers are not provided with a bonding structure, and the adjacent resonator layers are not required to be connected by bonding. When the filter is prepared, the deposition of the adjacent resonators can be directly carried out on one side of one resonator layer, which is far away from the substrate.

In the filter provided by the embodiment, the resonator layers are stacked on one side of the substrate along the thickness direction of the substrate, and the resonator layers form a vertical structure instead of a tiled structure, so that the area of a plane occupied by the filter is reduced, the integration level of the filter is improved, and the miniaturization of a communication system comprising the filter of the embodiment is facilitated. In addition, the filter of the embodiment only comprises one wafer, so that the number of wafers required in the filter is reduced, and the cost is saved; and adjacent resonator layers are in direct contact, so that the deposition of the adjacent resonator layers is directly carried out on one side of one resonator layer without adopting a bonding process, and the preparation process of the filter is simplified.

The technical solution in the embodiment of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiment of the present invention. All other embodiments obtained by a person of ordinary skill in the art based on the embodiments of the present invention without any creative work belong to the protection scope of the present invention.

Fig. 4 is a schematic structural diagram of another filter provided in an embodiment of the present invention, referring to fig. 4, optionally, the resonator layer 120 includes a lower electrode layer 121, a piezoelectric layer 122, an upper electrode layer 123, and a capping layer, which are stacked, where the lower electrode layer 121 of the same resonator layer 120 is located on one side of the upper electrode layer 123 close to the substrate 110, and thicknesses of corresponding setting film layers in at least two resonator layers 120 are different, and the setting film layer is at least one of the lower electrode layer 121, the upper electrode layer 123, and the piezoelectric layer 122.

In this embodiment, the resonator satisfies at least one of the following conditions: 1) the thicknesses of the upper electrode layers 123 in the at least two resonator layers 120 are different; 2) the thicknesses of the lower electrode layers 121 in the at least two resonator layers 120 are different; 3) the thickness of the piezoelectric layer 122 is different in at least two resonator layers 120. Among the two resonator layers 120 with different thicknesses of the upper electrode layer 123, due to the thickness difference of the upper electrode layer 123, the part of the resonator layer 120 with the thicker upper electrode layer 123, which is thicker than the upper electrode layer 123 of the resonator layer 120 with the thinner upper electrode layer 123, can be used as the mass loading layer of the resonator layer 120 with the thicker upper electrode layer 123; in the two resonator layers 120 with different thicknesses of the lower electrode layer 121, due to the thickness difference of the lower electrode layer 121, the part of the resonator layer 120 with the thicker lower electrode layer 121, which is thicker than the lower electrode layer 121 of the resonator layer 120 with the thinner lower electrode layer 121, can be used as the mass loading layer of the resonator layer 120 with the thicker lower electrode layer 121; in the two resonator layers 120 having different thicknesses of the piezoelectric layer 122, due to the difference in thickness of the piezoelectric layer 122, a portion of the resonator layer 120 having the piezoelectric layer 122 with a thicker thickness than the piezoelectric layer 122 of the resonator layer 120 having the piezoelectric layer 122 with a thinner thickness can be used as a mass loading layer of the resonator layer 120 having the piezoelectric layer 122 with a thicker thickness. In the filter of this embodiment, compared with the scheme in the prior art shown in fig. 3 and 4 in which only one resonator layer is disposed on the same substrate and the mass loading layer is prepared by controlling the thicknesses of the upper electrodes of the resonators in the same resonator layer, the thickness of the mass loading layer can be controlled by controlling at least one of the thickness difference of the upper electrode layers 123 in different resonator layers 120, the thickness difference of the lower electrode layers 121 in different resonator layers 120, and the thickness difference of the different resonator layers 122, specifically, the thickness of the mass loading layer can be controlled by controlling the thickness of at least one of the upper electrode layers 123, the lower electrode layers 121, and the piezoelectric layers 122 deposited in different resonator layers 120. That is, in the filter structure in the prior art, the mass loading layer is formed by a scheme that upper electrodes of different resonators in the same resonator layer have different thicknesses, and the mass loading layer and the upper electrode layer are equivalently connected together, so that the thickness of the mass loading layer is difficult to control and measure. In this embodiment, the thickness of the mass loading layer can be controlled by controlling the thickness of the set film layer deposited on different resonator layers by setting different thicknesses of the set film layers (at least one of the upper electrode layer 123, the lower electrode layer 121, and the piezoelectric layer 122) in at least two resonator layers, and the thickness of the mass loading layer can be measured by measuring the thickness of the set film layers on different resonator layers to calculate the thickness difference, so that the thickness of the mass loading layer can be accurately controlled and measured, which is beneficial to the accurate frequency modulation of the resonator layer 120.

Optionally, the material of the upper electrode layer 123 and the material of the lower electrode layer 121 may be at least one of metals such as molybdenum, aluminum, tungsten, or other alloy materials, or may be non-metal materials such as doped polysilicon. Alternatively, the deposited material of the piezoelectric layer 122 may be at least one of aluminum nitride, silicon oxide, and piezoelectric ceramic.

With continued reference to fig. 4, optionally, a cavity 125 is formed between the cap layer 124 and the upper electrode layer 123 of the same resonator layer, the resonator layer 120 includes a plurality of resonators, the resonators include a lower electrode 1211 located on the lower electrode layer 121, piezoelectric units (the case where each piezoelectric unit is continuous is schematically shown in fig. 3) located on the piezoelectric layer 122, and an upper electrode 1231 located on the upper electrode layer 123, and at least a portion of the lower electrode 1211, the piezoelectric units, and the upper electrode 1231 of the resonators are located in the cavity 125. Specifically, a cavity 125 is formed between the cap layer 124 and the upper electrode layer 123 of the same resonator layer, and at least part of the lower electrode 1211, at least part of the piezoelectric unit, and at least part of the upper electrode 1231 of the resonator layer are located in the cavity 125, so that at least part of the upper electrode layer 123, the piezoelectric unit 122, and the lower electrode layer 121 in the resonator layer 120 can be located in the sealed cavity 125, and the upper electrode layer 123, the piezoelectric layer 122, and the lower electrode layer 121 are protected from being corroded by water, oxygen, and the like.

On the basis of the above technical solution, optionally, the cap layer 124 is formed by deposition.

Alternatively, the material of the cap layer 124 may be amorphous silicon, polysilicon, silicon nitride, aluminum oxide, or the like. In this embodiment, the cap layer 124 of each resonator layer 120 in the filter is formed by deposition, and the process is simple. In addition, compared with a structure that two wafers are bonded together in the prior art, only one wafer (the substrate 110) is needed, and the cost is low.

With continued reference to fig. 4, optionally, one side of each resonator layer 120 proximate to the substrate 110 is provided with an acoustically reflective structure 111, with the acoustically reflective structure 111 being located on the substrate 110 or on the cap layer 124.

The acoustic reflection structure 111 may be a cavity on the side of the resonator layer 120 close to the substrate 110 shown in fig. 4, or may also be a bragg reflection layer, and the embodiment is not limited in this embodiment.

In other alternative embodiments of the present invention, a seed layer (not shown in fig. 4) may be further included between the lower electrode layer 121 and the substrate 110.

Optionally, the thicknesses of the upper electrode layers 123 of the respective resonator layers 120 are different, and/or the thicknesses of the lower electrode layers 121 of the respective resonator layers 120 are different.

Specifically, the thicknesses of the lower electrode layers 121 of the resonator layers 120 are the same, and the thicknesses of the upper electrode layers 123 of the resonator layers 120 are different from each other, so that the resonator layer 120 with the thicker upper electrode layer 123 forms a mass loading layer (a portion of the resonator layer 120 with the thicker upper electrode layer 123, which is thicker than the portion of the resonator layer 120 with the thinner upper electrode layer 123, of the upper electrode layer 123 forms a mass loading layer with respect to the resonator layer 120 with the thinner upper electrode layer 123) in any two resonator layers 120, and thus the mass loading layers of different resonator layers 120 have different thicknesses, and accordingly, different resonator layers 120 can have different resonance frequencies.

The thicknesses of the upper electrode layers 123 of the resonator layers 120 are the same, and the thicknesses of the lower electrode layers 121 of the resonator layers 120 are different from each other, so that a mass loading layer can be formed on the resonator layer 120 with the thicker lower electrode layer 121 relative to the resonator layer 120 with the thinner lower electrode layer 121 in any two resonator layers 120 (the part, thicker than the part, of the lower electrode layer 121, of the resonator layer 120 with the thicker lower electrode layer 121, of the lower electrode layer 121 is used as the mass loading layer in the resonator layer 120 with the thinner lower electrode layer 121), and thus the mass loading layers of different resonator layers 120 can have different thicknesses, and accordingly, different resonator layers 120 can have different resonant frequencies.

The thicknesses of the upper electrode layers 123 of the resonator layers 120 are the same, the thicknesses of the lower electrode layers 123 of the resonator layers 120 are the same, and the thicknesses of the piezoelectric layers 122 of the resonator layers 120 are different from each other, so that in any two resonator layers 120, the resonator layer 120 with the thicker piezoelectric layer 122 forms a mass loading layer relative to the resonator layer 120 with the thinner piezoelectric layer 122 (the part, in the resonator layer 120 with the thicker piezoelectric layer 122, of the piezoelectric layer 122 is thicker than the part, in the resonator layer 120 with the thinner piezoelectric layer 122, of the piezoelectric layer 122 serves as the mass loading layer), and thus the mass loading layers of different resonator layers 120 have different thicknesses, and accordingly, different resonator layers 120 can have different resonant frequencies.

Similarly, for the filter structure in which the thicknesses of the upper electrode layers 123 of the resonator layers 120 are different, the thicknesses of the lower electrode layers 121 of the resonator layers 120 are different, and the thicknesses of the piezoelectric layers 122 of the resonator layers 120 are different, the mass loading layers of different resonator layers 120 may have different thicknesses, and accordingly, different resonator layers 120 may have different resonant frequencies.

On the basis of the above technical solution, optionally, the thicknesses of the same film layers of the resonators of the same resonator layer 120 are the same.

Specifically, the upper electrodes of the resonators in the same resonator layer 120 have the same thickness, the lower electrodes of the resonators in the same resonator layer 120 have the same thickness, and the piezoelectric elements of the resonators in the same resonator layer 120 have the same thickness. The same film layer thickness of each resonator of the same resonator layer 120 is the same, compared with the prior art in which a plurality of resonators are tiled and arranged on one side of the substrate 110, and the structure with the same film layer thickness in the plurality of resonators is different, when one resonator layer 120 is prepared, only one deposition is performed on one film layer (which may be the upper electrode layer 123, the lower electrode layer 121 or the piezoelectric layer 122) in the resonator layer 120, and the same film layer structure with different thicknesses is formed without performing multiple depositions and/or multiple etchings in the prior art, so that the process is simplified.

In other alternative embodiments of the present invention, the thicknesses of the same film layers of at least two resonators in the same resonator layer may also be different, and the present invention is not specifically limited herein.

With continued reference to fig. 4, optionally, the filter further includes conductive leads 126, the conductive leads 126 for connecting resonators located in different resonator layers 120; the conductive leads 126 extend through at least one capping layer 124 in the thickness direction y of the filter.

Specifically, in the filter, the resonators of each resonator layer 120 are connected in series or in parallel to form the filter, and the conductive leads 126 penetrating the cap layer 124 of at least one of the layers may be used to connect the resonators located in different resonator layers 120. The resonators in the same resonator layer 120 may be connected by wires provided in the same resonator layer 120.

This embodiment also provides a method for manufacturing a filter, where the method for manufacturing a filter is used to manufacture a filter provided in any of the above embodiments of the present invention, fig. 5 is a flowchart of a method for manufacturing a filter provided in an embodiment of the present invention, and referring to fig. 5, the method for manufacturing a filter includes:

step 210, providing a substrate;

step 220, forming at least two resonator layers on one side of the substrate; when the adjacent resonator layers are formed on one side, far away from the substrate, of one resonator layer, the film layers of the adjacent resonator layers are directly deposited on one side, far away from the substrate, of the one resonator layer, so that at least two resonator layers are stacked on one side of the substrate in the thickness direction of the substrate and are in direct contact with the adjacent resonator layers.

The step of forming at least two resonator layers on one side of the substrate may be to form a resonator layer closest to the substrate first, and when forming the resonator layer closest to the substrate, specifically, a lower electrode layer, a piezoelectric layer, and an upper electrode layer may be formed in sequence at least at positions corresponding to a groove on the substrate, and then release the sacrificial material in the groove. After the resonator layer closest to the substrate is formed, the resonator layer closest to the substrate may be formed by forming another resonator layer one by one on the side away from the substrate, and finally at least two resonator layers stacked in the thickness direction of the substrate may be formed.

According to the preparation method of the filter provided by the embodiment, at least two resonator layers are formed on one side of the substrate, the at least two resonator layers are stacked on one side of the substrate along the thickness direction of the substrate, and each resonator layer forms a vertical structure rather than a tiled structure, so that the area of a plane occupied by the filter is reduced, the integration level of the filter is improved, and further the miniaturization of a communication system comprising the filter of the embodiment is facilitated. Moreover, the filter of the embodiment only includes one wafer (i.e., the substrate in the embodiment), so that the number of wafers required in the filter is reduced, which is beneficial to saving the cost; and adjacent resonator layers are in direct contact, so that the deposition of the adjacent resonator layers is directly carried out on one side of one resonator layer without adopting a bonding process, and the preparation process of the filter is simplified. On the basis of the above technical solution, optionally, at least two resonator layers are formed on one side of the substrate, including: at least two resonator layers stacked in a thickness direction of the substrate are formed layer by layer on one side of the substrate.

Fig. 6 is a flowchart of forming any resonator layer according to an embodiment of the present invention, and with reference to fig. 6, on the basis of the foregoing technical solution, optionally, forming any resonator layer of at least two resonator layers on one side of a substrate includes:

step 301, arranging an acoustic reflection structure inside or on the surface of the setting substrate.

When the acoustic reflection structure is arranged on the surface of the setting substrate, on which the resonator layer is arranged.

Fig. 7 is a schematic structural diagram of the acoustic reflection structure formed on the surface of the setting substrate according to the embodiment of the present invention, and referring to fig. 7, in the subsequent formation process of the resonator layer, a resonator may be correspondingly formed at a position corresponding to each acoustic reflection structure 111. The case of setting the base to the substrate 110 is schematically shown in fig. 7.

It should be noted that fig. 7 illustrates the acoustic reflection structure to be formed as a cavity structure, and the acoustic reflection structure may also be a bragg reflection layer, and when the acoustic reflection structure to be formed is a cavity structure, a sacrificial material may be filled in the cavity structure to be formed and released in a subsequent step.

Step 310, forming a lower electrode layer, a piezoelectric layer and an upper electrode layer on one side of a setting substrate in sequence; specifically, a lower electrode layer, a piezoelectric layer, and an upper electrode layer may be sequentially formed on a surface of a predetermined substrate on which an acoustic reflection structure is formed.

The forming of the lower electrode layer may include depositing the entire layer of lower electrode layer material, and patterning the entire layer of lower electrode layer material; similarly, the formation of the top electrode layer may include deposition of the entire layer of top electrode layer material and patterning of the entire layer of top electrode layer material. The forming of the piezoelectric layer may include the deposition of an entire layer of piezoelectric layer material, which may act as the piezoelectric layer; the piezoelectric layer can also be obtained by patterning the whole laminated piezoelectric layer material, and this embodiment is not limited in this respect.

In forming the lower electrode layer, it is necessary to ensure that the lower electrode layer at least partially covers the acoustic reflection structure. Also, when the acoustic reflection structure is a cavity structure, the sacrificial material in the cavity structure may be released after step 310.

Fig. 8 is a schematic structural diagram of a structure in which a lower electrode layer, a piezoelectric layer, and an upper electrode layer are sequentially formed on a surface of a predetermined substrate according to an embodiment of the present invention. Fig. 8 illustrates an example in which the substrate is set as the substrate 110, and the structure illustrated in fig. 8 illustrates a structure in which the lower electrode layer 121, the piezoelectric layer 122, and the upper electrode layer 123 in the resonator layer closest to the substrate 110 are formed.

Step 320, depositing a sacrificial material on one side of the upper electrode layer away from the setting substrate;

wherein the sacrificial material may be silicon oxide doped with phosphorus.

Step 330, patterning the sacrificial material to retain the sacrificial material corresponding to the location where the resonator is formed;

wherein the sacrificial material is retained in a position to form a cavity with the defined substrate.

Step 340, forming a cap layer on one side of the sacrificial material far away from the setting substrate;

step 350, patterning the cap layer to release the sacrificial material;

fig. 9 is a schematic structural diagram after releasing the sacrificial material between the upper electrode layer and the cap layer. In this step, the cap layer 124 is patterned to form a release hole for the sacrificial material, and the sacrificial material is released through the release hole, so as to form a cavity 125 between the cap layer and the set substrate. Also shown in fig. 9 are conductive leads 126 for connecting resonators in different resonator layers, wherein the conductive leads 126 may be formed in release holes in sacrificial material or separately etched to form vias through the capping layer of the conductive leads, which are then filled with conductive material to form the conductive leads.

It should be noted that in other embodiments of the present invention, the sacrificial material deposited on all the film layers can be released after the cap layer is patterned in step 350, that is, when the acoustic reflection structure is a cavity structure, the sacrificial material in the cavity structure can also be released together in step 350.

Wherein the base is set as a substrate or a cap layer.

Specifically, when a resonator layer closest to a substrate in a filter is formed, a base is set as the substrate; when other resonator layers on the side, far away from the substrate, of the resonator layer closest to the substrate in the filter are formed, the base is set to be a cover cap layer, and the cover cap layer is the cover cap layer in the resonator layer adjacent to the resonator layer to be formed in the thickness direction of the substrate.

Fig. 10 is a schematic structural diagram of a duplexer provided in an embodiment of the present invention, and referring to fig. 10, the duplexer includes a transmitting filter 101 and a receiving filter 102, where the transmitting filter 101 and/or the receiving filter 102 are filters according to any of the above embodiments of the present invention.

The duplexer of this embodiment includes the filter according to any of the above embodiments of the present invention, and accordingly, has the beneficial effects of the filter according to any of the above embodiments of the present invention, and details are not described herein again.

With continued reference to fig. 10, the transmission filter 101 and the reception filter 102 are optionally bonded in the substrate thickness y direction.

Specifically, the transmitting filter 101 and the receiving filter 102 are bonded and connected in the thickness direction of the substrate, so that on the basis that the resonator layer in the filter forms a vertical structure, the transmitting filter 101 and the receiving filter 102 in the duplexer also form a vertical structure, and further the planar area occupied by the duplexer is further reduced, the integration level of the duplexer is improved, and the miniaturization of a communication system is more facilitated.

With continued reference to fig. 10, optionally, the duplexer further includes a sealing ring 200, the sealing ring 200 is located between the transmitting filter 101 and the receiving filter 102, and the transmitting filter 101 and the receiving filter 102 are bonded and connected through the sealing ring 200.

A sealed space is formed between the sealing ring 200 and the transmitting filter 101 and between the sealing ring and the receiving filter 102, so that the structure of the transmitting filter 101 and the structure of the receiving filter 102 in the sealed space are protected in a sealed manner, and good working performance of the transmitting filter 101 and the receiving filter 102 in the duplexer is ensured. Moreover, the seal ring 200 is a common structure in the duplexer, and the transmitting filter 101 and the receiving filter 102 are bonded through the seal ring 200, so that an additional bonding structure does not need to be arranged in the duplexer, and the integration level of the duplexer is further improved. When bonding the transmission filter 101 and the reception filter 102, the respective seal rings 200 may be provided on the sides of the transmission filter 101 and the reception filter 102, respectively, and the seal rings 200 of the transmission filter 101 and the reception filter 102 may be aligned in the substrate thickness direction, and then the seal rings 200 of the two may be bonded.

With continued reference to fig. 10, optionally, the sealing ring 200 is disposed on the side of the resonator layer of the substrate of the transmitting filter 101 farthest from the transmitting filter 101 and on the side of the resonator layer of the substrate of the receiving filter 102 farthest from the receiving filter 102, and the resonator layer of the substrate of the transmitting filter 101 farthest from the transmitting filter 101, the resonator layer of the substrate of the receiving filter 102 farthest from the receiving filter 102, and the sealing ring 200 form a sealed structure.

Specifically, since the resonator layer of the substrate of the transmission filter 101 farthest from the transmission filter 101, the resonator layer of the substrate of the reception filter 102 farthest from the reception filter 102, and the seal ring 200 form a sealed structure, the seal ring 200 and the resonator layer of the substrate of the transmission filter 101 farthest from the transmission filter 101 may not include a cap layer, that is, the structure of the substrate of the transmission filter 101 farthest from the transmission filter 101 is an upper electrode layer; the resonator layer of the substrate farthest from the receive filter 102 in the receive filter 102 may not include a cap layer, that is, the structure of the substrate farthest from the receive filter 102 in the receive filter 102 is an upper electrode layer, so that the cap layer of the resonator layer farthest from the substrate in the transmit filter 101 and the receive filter 102 is saved, and the cost of the duplexer is reduced.

Fig. 11 is a schematic structural diagram of another duplexer provided in an embodiment of the present invention, in which the transmit filter 101 and the receive filter 102 in the duplexer are tiled on the surface of the substrate 300, and the connection between the resonator layer and the circuit 400 on the surface of the substrate 300 is completed through a lead penetrating through the substrate 300, where the transmit filter 101 and the receive filter 102 included in the duplexer in the embodiment are filters provided in any of the above-mentioned embodiments of the present invention, and have the beneficial effects of the filters in any of the above-mentioned embodiments of the present invention.

Embodiments of the present invention further provide a multiplexer, where the multiplexer includes the duplexer provided in any of the above embodiments of the present invention.

It is to be noted that the foregoing is only illustrative of the preferred embodiments of the present invention and the technical principles employed. It will be understood by those skilled in the art that the present invention is not limited to the particular embodiments described herein, but is capable of various obvious changes, rearrangements and substitutions as will now become apparent to those skilled in the art without departing from the scope of the invention. Therefore, although the present invention has been described in greater detail by the above embodiments, the present invention is not limited to the above embodiments, and may include other equivalent embodiments without departing from the spirit of the present invention, and the scope of the present invention is determined by the scope of the appended claims.