WO2021253757A1 - Thin-film acoustic wave filter and manufacturing method therefor - Google Patents

Abstract

The present invention provides a thin-film acoustic wave filter and a manufacturing method therefor. The thin-film acoustic wave filter comprises: a first substrate comprising a first surface and a second surface disposed opposite to each other, the first surface being provided with a first cavity; an acoustic wave resonator unit disposed on the first substrate, covering the first cavity, and comprising a first electrode, a piezoelectric layer and a second electrode, wherein the first electrode and the second electrode are respectively disposed on two opposite surfaces of the piezoelectric layer, or the first electrode and the second electrode are both arranged on a side of the piezoelectric layer facing the first cavity and are disposed opposite to each other; a first through-hole passing through the first substrate and extending to the first electrode; a second through-hole passing through the first substrate and extending to the second electrode; a conductive layer covering inner walls of the first through-hole and the second through-hole and the second surface of the first substrate; and an inductor and/or a capacitor disposed on a side of the second surface of the first substrate.

Description

Thin film acoustic wave filter and manufacturing method thereof Technical field

The invention relates to the field of semiconductor device manufacturing, in particular to a thin-film acoustic wave filter and a manufacturing method thereof.

Background technique

With the continuous development of wireless communication technology, in order to meet the multi-functional requirements of various wireless communication terminals, terminal equipment needs to be able to use different carrier frequency spectrums to transmit data. At the same time, in order to support sufficient data transmission rates within a limited bandwidth, The radio frequency system also puts forward strict performance requirements. The radio frequency filter is an important part of the radio frequency system. It can filter out the interference and noise outside the communication spectrum to meet the signal-to-noise ratio requirements of the radio frequency system and the communication protocol. Taking a mobile phone as an example, since each frequency band needs a corresponding filter, dozens of filters may need to be set in a mobile phone.

Generally, the film bulk acoustic wave resonator includes two film electrodes, and a piezoelectric film layer is arranged between the two film electrodes. Its working principle is to use the piezoelectric film layer to generate vibration under an alternating electric field. The bulk acoustic wave propagating in the thickness direction of the electric film layer is transmitted to the interface between the upper and lower electrodes and the air to be reflected back, and then reflected back and forth inside the film to form an oscillation. When the sound wave propagates in the piezoelectric film layer exactly an odd multiple of the half wavelength, a standing wave oscillation is formed.

technical problem

However, the traditionally produced thin-film acoustic wave filter needs to be soldered with the PCB board after the basic structure is manufactured before it can be supplied to customers, because the filter needs to be matched with the capacitor and inductance designed inside the PCB board. According to the number of metal layers, the thickness of the PCB board ranges from 200um to 700um, It takes up space very much. Therefore, how to reduce the overall volume of the device and reduce the packaging cost is a problem currently faced.

Technical solutions

The invention discloses a thin film acoustic wave filter and a manufacturing method thereof, which can solve the problem of large volume of the thin film acoustic wave filter.

In order to solve the above technical problems, the present invention provides a thin film acoustic wave filter, including:

A first substrate, the first substrate including a first surface and a second surface opposed to each other;

The first surface is provided with a first cavity;

The acoustic wave resonator unit is arranged on the first substrate and covers the first cavity. The acoustic wave resonator unit includes a first electrode, a piezoelectric layer, and a second electrode; wherein the first electrode and the The second electrodes are respectively disposed on two opposite surfaces of the piezoelectric layer; or, the first electrode and the second electrode are both disposed on the side of the piezoelectric layer facing the first cavity, And relatively set;

A first through hole penetrates the first substrate and extends to the first electrode;

A second through hole penetrates the first substrate and extends to the second electrode;

A conductive layer covering the inner walls of the first through hole and the second through hole and the second surface of the first substrate;

The inductor and/or the capacitor are located on the second surface side of the first substrate.

The present invention also provides a method for manufacturing a thin-film acoustic wave filter, including:

Forming an acoustic wave resonator unit, the acoustic wave resonator unit including a piezoelectric layer, and a resonant electrode on the surface of the piezoelectric layer;

Forming a first substrate with a first cavity on the surface of the piezoelectric layer, the first cavity is open on one side, and the opening faces the resonance electrode;

Under a preset temperature and pressure: forming a through hole penetrating the first substrate on the periphery of the first cavity, the through hole extending to the resonance electrode;

Forming a metal plating layer to cover the inner wall of the through hole and the surface of the first substrate;

The metal plating layer is patterned to form a conductive layer and an inductor and/or a capacitor.

Beneficial effect

The beneficial effects of the present invention are: the production of matching capacitors and inductors on devices with cavities and functional units on the cavities through an electroplating process at a preset temperature, the production of capacitors and inductors is compatible with the thin film acoustic wave filter Production process, and use the conductive layer process required for TSV through-hole connection to form all or part of the capacitor/inductance, so that the interconnection distance between the capacitor inductance and the thin film acoustic wave filter is short, and the performance is better; no additional process is required to realize the function Integration simplifies the procedure of making capacitors/inductors separately, saves the high cost of the packaging process, and reduces the thickness of the device.

Description of the drawings

By describing the exemplary embodiments of the present invention in more detail with reference to the accompanying drawings, the above and other objectives, features, and advantages of the present invention will become more apparent. In the exemplary embodiments of the present invention, the same reference numerals generally represent the same components. .

Fig. 1 shows a schematic structural diagram of a thin-film acoustic wave filter according to Embodiment 1 of the present invention.

Fig. 2 shows a schematic structural diagram of a thin-film acoustic wave filter according to another embodiment of the present invention.

Fig. 3 shows a schematic structural diagram of a thin-film acoustic wave filter according to another embodiment of the present invention.

4 to 10 show schematic structural diagrams corresponding to different steps of a method for manufacturing a thin-film acoustic wave filter of Embodiment 2.

FIG. 11 shows a schematic diagram of the structure corresponding to different steps of a method for manufacturing a thin-film acoustic wave filter of Embodiment 3.

FIG. 12 shows a schematic diagram of the structure corresponding to different steps of a method of manufacturing a thin-film acoustic wave filter of Embodiment 4

Description of reference signs:

10-first substrate; 20-second base; 100-first substrate; 200-capping layer; 200A-first semiconductor layer; 200B-first device layer; 300-second substrate; 101-bonding layer 102-support layer; 103-first electrode; 103A-first interdigital transducer; 105A-second interdigital transducer; 104-piezoelectric layer; 105-second electrode; 106-adhesive layer; 107-inductance; 108-capacitance; 1081-insulating layer; 109-conductive layer; 110a-first cavity; 110b-second cavity; 120-conductive interconnection structure; 160-insulating layer; 140-via; 160 -Passivation layer; 130a-first trench; 130b-second trench.

Embodiments of the present invention

Hereinafter, the present invention will be further described in detail with reference to the accompanying drawings and specific embodiments. According to the following description and drawings, the advantages and features of the present invention will be clearer. However, it should be noted that the concept of the technical solution of the present invention can be implemented in many different forms and is not limited to the specific implementation set forth herein. example. The drawings all adopt a very simplified form and all use imprecise proportions, which are only used to conveniently and clearly assist in explaining the purpose of the embodiments of the present invention.

It should be understood that when an element or layer is referred to as being "on", "adjacent to", "connected to" or "coupled to" other elements or layers, it can be directly on the other elements or layers. On a layer, adjacent to, connected to, or coupled to other elements or layers, or intervening elements or layers may be present. In contrast, when an element is referred to as being "directly on", "directly adjacent to", "directly connected to" or "directly coupled to" other elements or layers, there are no intervening elements or layers. Floor. It should be understood that although the terms first, second, third, etc. may be used to describe various elements, components, regions, layers and/or sections, these elements, components, regions, layers and/or sections should not be limited by these terms. These terms are only used to distinguish one element, component, region, layer or section from another element, component, region, layer or section. Therefore, without departing from the teachings of the present invention, the first element, component, region, layer or section discussed below may be represented as a second element, component, region, layer or section.

Spatial relation terms such as "under", "below", "below", "below", "above", "above", etc., in It can be used here for the convenience of description to describe the relationship between one element or feature shown in the figure and other elements or features. It should be understood that, in addition to the orientations shown in the figures, the spatial relationship terms are intended to include different orientations of devices in use and operation. For example, if the device in the drawing is turned over, then elements or features described as "under" or "under" or "under" other elements will be oriented "on" the other elements or features. Therefore, the exemplary terms "below" and "below" can include both an orientation of above and below. The device can be otherwise oriented (rotated by 90 degrees or other orientations) and the spatial descriptors used here are interpreted accordingly.

The purpose of the terms used here is only to describe specific embodiments and not as a limitation of the present invention. When used herein, the singular forms "a", "an" and "the/the" are also intended to include plural forms, unless the context clearly dictates otherwise. It should also be understood that the terms "composition" and/or "including", when used in this specification, determine the existence of the described features, integers, steps, operations, elements and/or components, but do not exclude one or more other The existence or addition of features, integers, steps, operations, elements, components, and/or groups. As used herein, the term "and/or" includes any and all combinations of related listed items.

If the method herein includes a series of steps, and the order of these steps presented herein is not necessarily the only order in which these steps can be performed, and some steps may be omitted and/or some other steps not described herein may be added to this method. If the components in a certain drawing are the same as those in other drawings, although these components can be easily identified in all the drawings, in order to make the description of the drawings more clear, this specification will not describe all the same components. The reference numbers are shown in each figure.

Example 1

Embodiment 1 of the present invention provides a thin film acoustic wave filter. FIG. 1 shows a schematic structural diagram of a thin film acoustic wave filter according to Embodiment 1. Please refer to FIG. 1. The thin film acoustic wave filter includes:

A first substrate 10, which includes a first surface and a second surface opposite to each other;

The first surface is provided with a first cavity 110a;

The acoustic wave resonator unit is disposed on the first substrate and covers the first cavity 110a, and the acoustic wave resonator unit includes a first electrode 103, a piezoelectric layer 104, and a second electrode 105;

The first electrode 103 and the second electrode 105 are respectively disposed on two opposite surfaces of the piezoelectric layer 104;

The first through hole 140 is disposed outside the first cavity 110a, penetrates the first substrate 10, and extends to the first electrode 103;

The first through hole 150 is disposed outside the first cavity 110a, penetrates the first substrate 10, and extends to the second electrode 105;

The conductive layer 109 covers the inner walls of the first through hole 140 and the second through hole 150 and the second surface of the first substrate;

The inductor 107 and/or the capacitor 108 are located on the second surface side of the first substrate 10.

Specifically, in this embodiment, an air-gap thin-film piezoelectric acoustic wave filter is taken as an example for description. The first substrate 10 is the lower substrate of the filter and serves as a carrier for forming the filter (located in the lower part of the entire filter). The first substrate 10 may have a single-layer structure or a double-layer structure. The first substrate 10 of this embodiment has a double-layer structure and includes a first substrate 100 and a support layer 102 provided on the first substrate.

The support layer 102 is disposed on the first surface of the first substrate 10, and the support layer 102 encloses the first cavity 110a. The first cavity 110a may be formed by etching the support layer 102 through an etching process. The first substrate 100 and the supporting layer 102 may be bonded together by a bonding layer, and the material of the bonding layer includes silicon oxide or silicon nitride. The supporting layer 102 may also be formed on the first substrate 100 by deposition. In this embodiment, the first cavity 110a is a closed cavity, and the shape of the bottom surface is rectangular. However, in other embodiments of the present invention, the shape of the first cavity 110a on the bottom surface of the first electrode 103 may also be circular. , Ellipse or polygons other than rectangles, such as pentagons, hexagons, etc.

The material of the first substrate 100 includes silicon (Si), germanium (Ge), silicon germanium (SiGe), silicon carbon (SiC), silicon germanium carbon (SiGeC), indium arsenide (InAs), gallium arsenide (GaAs) , Indium Phosphide (InP) or other III/V compound semiconductors, etc. The material of the support layer 102 includes one or more combinations of silicon dioxide, silicon nitride, aluminum oxide, and aluminum nitride. When the first substrate 10 has a single-layer structure, the reference of the first substrate 10 may refer to the material of the first substrate 100.

An acoustic wave resonator unit is provided above the first substrate 10, and the acoustic wave resonator unit covers the first cavity 110a. The acoustic wave resonator unit includes a first electrode 103, a piezoelectric layer 104, and a second electrode 105 from bottom to top. The first electrode 103 is located on the supporting layer 102, the piezoelectric layer 104 is located on the first electrode 103, and the second electrode 105 is located on the piezoelectric layer 104. In this embodiment, it further includes a first trench 130a and a second trench 130b. The first trench 130a is located on the lower surface of the piezoelectric laminate structure on the side where the first cavity 110a is located, and penetrates the first electrode. 103. The second trench 130 b is located on the upper surface of the piezoelectric laminate structure and penetrates the second electrode 105. The two ends of the first groove 130a and the two ends of the second groove 130b are arranged opposite to each other, so that the projection of the first groove 130a and the second groove 130b on the first substrate 10 The two junctions meet or have a gap. In this embodiment, the projections of the first groove 130a and the second groove 130b on the first substrate 10 are closed patterns, which constitute the effective resonance region of the resonator. The first electrode 103, the piezoelectric layer 104, and the second electrode 105 in the effective resonance region are superimposed on each other in a direction perpendicular to the first substrate 10, and the boundary of the effective resonance region is located in the first cavity 110a. within the area. The shape of the effective resonance area is an irregular polygon, such as a pentagon or hexagon without parallel opposite sides.

A first through hole 140 and a second through hole 150 are provided outside the first cavity 110a. The first through hole 140 penetrates the first substrate 10 and extends to the first electrode 103, and the second through hole 150 penetrates through the first electrode 103. A substrate 10 extends to the second electrode 105.

The conductive layer 109 covers the inner walls of the first through hole 140 and the second through hole 150 and the second surface of the first substrate 10. The conductive layer 109 covers the inner walls of the first through holes 140 and the second through holes 150. There are two cases. One is that the conductive layer 109 only covers the inner walls of the through holes 140 and the second through holes 150, and the other is the first The through hole 140 and the second through hole 150 are filled with a conductive layer. A capacitor 108 and/or an inductor 107 are provided on the second surface side of the first substrate 10. In this embodiment, the two ends of the inductor 107 and/or the capacitor 108 are electrically connected to the first electrode 103 and the second electrode 105 through the conductive layer 109, respectively. In another embodiment, the inductor and/or capacitor and the conductive layer are formed by the same layer of conductive material. The inductor may be a spiral inductor on the plane of the conductive material formed by the same layer of conductive material. In other embodiments, the inductor may include a spiral sub-inductor on the plane of the conductive material, and also include other spiral inductors on the plane parallel to the conductive material. The spiral sub-inductor, that is, the inductor includes a multi-layer spiral sub-inductor. Or one layer of conductive material, for example, a spiral-shaped first sub-inductor is provided on the metal seed layer, a spiral-shaped second sub-inductor is provided on the electroplating material layer, and an insulating material is arranged between the sub-inductors at the position of the inductance.

The capacitor 108 includes a first electrode plate and a second electrode plate. The first electrode plate and the second electrode plate are perpendicular to the surface of the first substrate 10 or parallel to the surface of the first substrate 10. An insulating layer is provided between the first electrode plate and the second electrode plate. In this embodiment, the first electrode plate and the second electrode plate of the capacitor 108 are both arranged parallel to the first substrate 100. The material of the conductive layer 109 is a metal material, such as copper, tungsten, and the like. In this embodiment, a passivation layer 160 is further provided on the surface of the conductive layer 109, and the passivation layer 160 is used to protect the conductive layer 109 from outside air pollution, such as moisture and dust.

In this embodiment, the inductor 107 and/or the capacitor 108 are disposed in the peripheral area of the first cavity 110a. In order to reduce the influence of the magnetic field formed after the capacitor or the inductor is energized on the acoustic wave resonator unit. When a plurality of first cavities are formed on the first substrate, the inductor and/or the capacitor may be arranged between two adjacent first cavities, as far away as possible from the acoustic wave resonator unit.

In this embodiment, an etch stop layer (not shown in the figure) is further provided between the support layer 102 and the first electrode 103, the material of which includes but is not limited to silicon nitride (Si3N4) and silicon oxynitride (SiON). On the one hand, the etch stop layer can be used to increase the structural stability of the finally manufactured thin film bulk acoustic wave resonator. On the other hand, the etch stop layer has a lower etching rate than the support layer 102, and can be used to etch the support The layer 102 prevents over-etching during the process of forming the first cavity 110a, and protects the surface of the first electrode 103 located thereunder from damage, thereby improving the performance and reliability of the device.

In this embodiment, it further includes a capping layer 200, which is arranged on the side of the acoustic wave resonator unit opposite to the first cavity 110a. The capping layer 200 and the acoustic wave resonator unit are connected by an adhesive layer 106. The laminate 106 encloses the second cavity 110b, and the capping layer 200 seals the second cavity 110b. The second cavity 110b exposes the surface of the acoustic wave resonator unit, and the second cavity 110b is located above the area enclosed by the first cavity 110a.

In this embodiment, the capping layer 200 is further provided with a first micro-device 2000. Specifically, the capping layer 200 includes a first semiconductor layer 200A and a first device layer 200B. The first device layer 200B is close to the side of the second cavity 110b, and the first micro device 2000 is at least partially formed In the first device layer 200B. The first micro-device 2000 includes: a diode, a triode, a MOS transistor, an electrostatic discharge protection device, a resistor, a capacitor, or an inductor. When the first micro-device 2000 is a resistor, a capacitor, or an inductor, the first micro-device 2000 may all be located in the device layer 200B. When the first micro-device 2000 is a triode or a MOS transistor, its source and drain levels It may be located in the first semiconductor layer 200A. It also includes an electrical connection structure, which is connected to the first micro-device 2000 to draw out the electrical properties of the first micro-device 2000. In this embodiment, the electrical connection structure is a conductive plug 2001, which extends from the bottom surface of the first substrate 10 to the first micro-device 2000.

The material of the first semiconductor layer 200A includes silicon (Si), germanium (Ge), silicon germanium (SiGe), silicon carbon (SiC), silicon germanium carbon (SiGeC), indium arsenide (InAs), gallium arsenide (GaAs) , Indium Phosphide (InP) or other III/V compound semiconductors, etc. The material of the first device layer 200B includes silicon oxide, silicon nitride, silicon oxynitride, and silicon carbonitride. The first device layer 200B and the adhesive layer 106 are combined by bonding. The material of the adhesion layer 106 can be any suitable dielectric material, including but not limited to silicon oxide, silicon nitride, silicon oxynitride, silicon carbonitride, or ethyl silicate. When the materials of the first device layer 200B and the adhesive layer 106 are the same, they can be directly bonded by using atomic bonding. When the materials of the first device layer 200B and the adhesion layer 106 are different, a bonding layer can be formed on the bonding surface of the two. The material of the bonding layer includes: silicon oxide, silicon nitride, polysilicon, and ethyl silicate. Ester or organic curing film. In this embodiment, the first device layer 200B and the adhesion layer 106 are both silicon oxide, and atomic bonds are used for bonding, the bonding structure is strong and the process flow is simple. When bonding is performed through a bonding layer, a bonding layer structure is formed between the adhesive layer 106 and the first device layer 200B. It can be seen from the materials of the adhesive layer and the bonding layer that the materials of the two may be the same or different.

It should be noted that, in this embodiment, the first through hole 140 and the second through hole 150 extend upward from below the filter and penetrate the first substrate 10. In another embodiment, the first through hole 140 and the second through hole 150 may also extend downward from above the filter and penetrate the capping layer and the adhesive layer. When the through hole extends downward from the top of the filter, the conductive layer is located on the surface of the capping layer. At this time, the "capping layer" is equivalent to the "first substrate", and the "adhesive layer" is equivalent to the "supporting layer".

Referring to FIG. 2, in another embodiment, the acoustic wave filter is a firmly installed bulk acoustic wave filter, and the first substrate 10 is the upper cover of the filter. The first electrode 103 is close to the first substrate 10, and the second electrode 105 is far away from the first substrate 10. A second substrate 300 is included below the second electrode 105, and the second substrate 300 is provided with a Bragg reflection layer (the Bragg reflection layer in the dashed line frame is formed by alternating high acoustic impedance layers and low acoustic impedance layers).

3, in another embodiment, the acoustic wave filter is a surface acoustic wave filter, and the first electrode 103 and the second electrode 105 are both disposed on the piezoelectric layer 104 facing the first cavity 110a , And set relative to each other. The first electrode 103 and the second electrode 105 are a first interdigital transducer and a second interdigital transducer. The first substrate 10 is the upper cover of the filter.

Example 2

Embodiment 2 of the present invention provides a method for manufacturing a thin-film acoustic wave filter, which includes the following steps:

S01: forming an acoustic wave resonator unit, the acoustic wave resonator unit including a piezoelectric layer, and a resonant electrode on the surface of the piezoelectric layer;

S02: forming a first substrate with a first cavity on the surface of the piezoelectric layer, the first cavity is open on one side, and the opening faces the resonance electrode;

S03: At a preset temperature and pressure: a through hole penetrating the first substrate is formed on the periphery of the first cavity, and the through hole extends to the resonance electrode;

S04: forming a metal plating layer to cover the inner wall of the through hole and the surface of the first substrate; patterning the metal plating layer to form a conductive layer and an inductor and/or a capacitor.

It should be noted that SON is not used to limit the sequence of steps. 4 to 9 show schematic diagrams of different stages of the manufacturing method of a thin-film acoustic wave filter according to Embodiment 2 of the present invention. Please refer to FIGS. 4 to 10 to describe each step in detail. To

In this embodiment, the resonance electrode includes a first electrode and a second electrode located on different sides of the piezoelectric layer, and forming an acoustic wave resonator unit includes:

4, a supporting substrate 400 is provided, on which the second electrode layer 105', the piezoelectric layer 104, and the first electrode layer 103' are sequentially formed.

The carrier substrate 400 may be at least one of the materials mentioned below: silicon (Si), germanium (Ge), silicon germanium (SiGe), silicon carbon (SiC), silicon germanium (SiGeC), indium arsenide ( InAs), gallium arsenide (GaAs), indium phosphide (InP) or other III/V compound semiconductors, ceramic substrates such as alumina, quartz or glass substrates can also be used.

The materials of the second electrode layer 105' and the first electrode layer 103' can use any suitable conductive material or semiconductor material well known to those skilled in the art, wherein the conductive material can be a metal material with conductive properties, for example, made of molybdenum ( Mo), aluminum (Al), copper (Cu), tungsten (W), tantalum (Ta), platinum (Pt), ruthenium (Ru), rhodium (Rh), iridium (Ir), chromium (Cr), titanium ( Ti), gold (Au), osmium (Os), rhenium (Re), palladium (Pd) and other metals or laminated layers of the above metals, semiconductor materials such as Si, Ge, SiGe, SiC, SiGeC, etc. The second electrode layer 105' and the first electrode layer 103' can be formed by physical vapor deposition or chemical vapor deposition methods such as magnetron sputtering, vapor deposition, or the like. The material of the piezoelectric layer 104 can be aluminum nitride (AlN), zinc oxide (ZnO), lead zirconate titanate (PZT), lithium niobate (LiNbO3), quartz (Quartz), potassium niobate (KNbO3) or tantalic acid Piezoelectric materials with wurtzite crystal structure such as lithium (LiTaO3) and their combinations. When the piezoelectric layer 104 includes aluminum nitride (AlN), the piezoelectric layer 104 may further include a rare earth metal, such as at least one of scandium (Sc), erbium (Er), yttrium (Y), and lanthanum (La). In addition, when the piezoelectric layer 104 includes aluminum nitride (AlN), the piezoelectric layer 104 may further include a transition metal, such as at least one of zirconium (Zr), titanium (Ti), manganese (Mn), and hafnium (Hf). kind. The piezoelectric layer 104 can be deposited and formed by any suitable method known to those skilled in the art, such as chemical vapor deposition, physical vapor deposition, or atomic layer deposition. Optionally, in this embodiment, the second electrode 105 and the first electrode 103 are made of metal molybdenum (Mo), and the piezoelectric layer 104 is made of aluminum nitride (AlN).

A first substrate with a first cavity is formed on the surface of the piezoelectric layer, the first cavity is opened on one side, and the opening faces the resonance electrode. The first substrate with the first cavity in this embodiment includes a support layer with the first cavity, and a first substrate on the support layer. The first cavity opening faces the first electrode in the resonance electrode. The first electrode is formed during the formation of the first substrate, and the second electrode is formed after the first electrode.

5, a support layer 102 is formed on the first electrode layer 103', and a first cavity 110a penetrating the support layer 102 is formed in the support layer 102. The support layer 102 is formed by physical vapor deposition or chemical vapor deposition. The material of the support layer 102 may be any suitable dielectric material, including but not limited to at least one of silicon oxide, silicon nitride, silicon oxynitride, silicon carbonitride, and the like.

Referring to FIG. 6, the support layer 102 is etched by an etching process to form a first cavity 110a, and the first electrode layer 103' at the bottom is exposed. The etching process may be wet etching or dry etching. Dry etching includes but is not limited to reactive ion etching (RIE), ion beam etching, and plasma etching. The depth and shape of the first cavity 110a depend on the depth and shape of the cavity required for the bulk acoustic wave resonator to be manufactured, that is, the depth of the first cavity 110a can be determined by forming the thickness of the support layer 102. The shape of the bottom surface of the first cavity 110a may be a rectangle or a polygon other than a rectangle, such as a pentagon, a hexagon, an octagon, etc., and may also be a circle or an ellipse.

In another embodiment, the method of forming the first substrate with the first cavity is: forming a first sacrificial layer to cover the first electrode layer; forming a first dielectric layer to cover the first sacrificial layer, The first electrode layer; the first sacrificial layer is removed to form a first cavity; the first substrate includes the first dielectric layer.

Referring to FIG. 7, the first electrode layer 103' is patterned to form the first electrode 103, and the first substrate 100 is bonded on the support layer 102. In this embodiment, the first substrate 100 and the supporting layer 102 are bonded together through a bonding layer, and the bonding layer includes silicon oxide, silicon nitride, polysilicon, ethyl silicate, or organic cured film. In this embodiment, the patterning of the first electrode layer 103' is to form a first trench 130a in the first electrode layer 103' by etching, and the first trench 130a penetrates the first electrode layer 103' and has a semi-annular shape. .

Referring to FIG. 8, the carrier substrate is removed, the second electrode layer 105' is patterned, and the second electrode 105 is formed. The carrier substrate 400 may be removed by mechanical grinding. In this embodiment, the second electrode layer 105' is patterned to form a second trench 130b by etching in the second electrode layer 105', and the second trench 130b penetrates the second electrode layer 105' and has a semi-annular shape. . The projection of the first groove 130a and the second groove 130b in the direction of the piezoelectric layer is a closed ring. The inside of the ring is the effective resonance area of the resonator.

Referring to FIG. 9, this embodiment further includes: forming a capping layer 200 above the second electrode 105, and forming a second cavity 110 b between the capping layer 200 and the second electrode 105. The capping layer 200 is adhered to the second electrode 105 through the adhesive layer 106. The second cavity 110b is a sealed cavity. The capping layer serves as an effective support for the subsequent manufacturing process, ensuring the mechanical strength of the filter with a cavity structure, matching the process conditions of the grinding and etching processes, and maintaining the pressure balance of the first cavity and the second cavity.

Referring to FIG. 10, at a preset temperature and pressure: a first substrate is formed on the periphery of the first cavity 110a (the first substrate 100 and the support layer 102 in this embodiment jointly constitute the first substrate) Through holes, the through holes in this embodiment include a first through hole 140 and a second through hole 150. The first through hole 140 extends to the first electrode 103, and the second through hole 150 extends to the second through hole.极105。 Electrode 105.

In this embodiment, the preset temperature is less than or equal to 500°C, and the preset pressure is less than or equal to 2 standard atmospheric pressures, such as 0°C, 100°C, 200°C, 300°C, and 400°C. The method of forming the first through hole 140 and the second through hole 150 penetrating the first substrate 100 and the supporting layer 103 includes: using the capping layer 200 as a carrier to form the first substrate 100 and the second through hole 150. The first through hole 140 and the second through hole 150 of the support layer 102 are described. In a later process, a conductive material is formed in the first through hole 140 and the second through hole 150 to electrically connect the first electrode and the second electrode with external signals.

In this embodiment, before forming the first through hole 140 and the second through hole 150, a thinning process is performed on the second surface of the first substrate 100. The first substrate is thinned to 60 to 100 microns.

Continuing to refer to FIG. 10, a metal plating layer is formed to cover the inner walls of the first through holes 140 and the second through holes 150 and the second surface of the first substrate 100 (the side away from the first cavity); and the metal plating layer is patterned , A conductive layer 109, an inductor 107 and/or at least part of the capacitor 108 are formed. In this embodiment, both ends of the inductor 107 and/or the capacitor 108 are electrically connected to the first electrode 103 and the second electrode 105 through the conductive layer 109, respectively.

In this embodiment, the method of forming a metal plating layer includes: forming a metal seed layer on the inner wall of the first through hole 140 and the second through hole 150 and the second surface of the first substrate 100. Specifically, physical vapor deposition is used to form a titanium thin film with a thickness of 1000-3000 angstroms on the inner wall and second surface of the first through hole 140 and the second through hole 150, and 3000 to 3000 angstroms are formed on the surface of the titanium thin film by physical vapor deposition. -5000 Angstroms of copper metal film. The titanium film and the copper film together constitute the seed layer. Afterwards, an electroplating material layer is formed on the surface of the seed layer through an electroplating process. Wherein, the electroplating material layer in the first through hole 140 and the second through hole 150 can only cover the surface of the seed layer (preserving the shape of the through hole), and the electroplating material layer can also connect the first through hole 140 and the second through hole. The hole 150 is filled. The seed layer and the electroplating material layer together constitute the metal plating layer.

In another embodiment, the method of forming a metal plating layer includes forming a metal plating layer in the first through hole 140 and the second through hole 150 and on the second surface by using a low-temperature vapor deposition process. The inductor 107 can be formed by patterning the metal plating layer.

The capacitor includes a first electrode plate and a second electrode plate arranged in parallel. In one embodiment, the first electrode plate is perpendicular to the first substrate, and forming the capacitor includes: patterning the metal plating layer to form a through In the insulating trench of the metal plating layer, an insulating dielectric material is filled in the insulating trench to form the first electrode plate and the second electrode plate that are composed of the metal plating layer and are insulated from each other.

In another embodiment, the first electrode plate and the second electrode plate of the capacitor are parallel to the surface of the first substrate, and the method for forming the conductive layer and the inductor and/or the capacitor includes: forming a first metal plating layer, and filling the The first through hole and the second through hole cover the surface of the first substrate, the first metal plating layer is patterned, conductive plugs are formed in the first through hole and the second through hole, and The first plate of the capacitor; a dielectric layer exposing the conductive plug is formed on the first metal plating layer; a second metal plating layer is formed on the dielectric layer, and the second metal plating layer is patterned, The conductive layer connecting the conductive plug and the second electrode plate of the capacitor are formed, and the second metal plating layer is patterned to form the inductor.

In another embodiment, inductors are formed in both the first metal plating layer and the second metal plating layer, and the inductors in the first metal plating layer and the second metal plating layer may be independent inductors or a whole inductor.

In another embodiment, the metal plating layer includes a metal seed layer and an electroplating material layer. When the metal seed layer is made, the first electrode plate of the capacitor and/or the spiral first sub-inductor of the inductor are formed. Yes, to form the second plate of the capacitor and/or the spiral second sub-inductor of the inductor, an insulating material is provided between the metal seed layer and the electroplating material layer at the position of the capacitor and the inductor, and the first plate and the second There is an insulating material between the two pole plates, and there is an insulating material between the first sub-inductor and the second sub-inductor.

In this embodiment, the inductor or capacitor is formed in the outer area of the first cavity to prevent the magnetic field formed by the inductor or capacitor from affecting the resonator. When there are multiple first cavities, the inductor and the capacitor may be located in the area between the two first cavities, away from the effective resonance region of the resonator.

This embodiment protects the functional unit devices from damage by using the capping layer as a support at a preset low temperature, through low-temperature grinding, deposition, electroplating, photolithography, or etching, etc., to form a conductive layer on the first substrate. At the same time, the formation of inductors and/or capacitors does not require additional processes to achieve functional integration, eliminates the need for PCB boards, and also eliminates the high cost of packaging processes, and achieves a reduction in device thickness.

Example 3

The difference between this embodiment and the second embodiment is that the first through hole and the second through hole are formed on the side where the capping layer is located.

Referring to FIG. 11, in this embodiment, the steps before forming the capping layer 200 are the same as in Embodiment 2. Referring to FIG. 9, after the capping layer is formed, referring to FIG. And the first through hole 140 and the second through hole 150 of the adhesive layer 106, the first through hole 140 extends to the first electrode 103, and the second through hole 150 extends to the second electrode 105. The subsequent process is similar to that of the second embodiment. I won't repeat them here.

In another embodiment, after the first substrate 100 is formed on the supporting layer 102, before removing the supporting base 400 (refer to the structure of FIG. 7), the supporting base 400 is used as a carrier to form a penetrating first substrate. 100 and the first through hole and the second through hole of the support layer 102, the first through hole 140 extends to the first electrode 103, and the second through hole 150 extends to the second electrode 105. Refer to Example 2 for other steps.

Example 4

The thin film acoustic wave filter formed in this embodiment is a surface acoustic wave filter, and the resonant electrode includes a first interdigital transducer and a second interdigital transducer on the same side of the piezoelectric layer, forming an acoustic wave resonator unit The steps of and through holes include:

12, a second substrate 20 is provided, a piezoelectric layer 104 and a conductive material layer are sequentially formed on the second substrate 20, and the conductive material layer is patterned to form a first interdigital transducer 103A and a second fork Refers to the transducer 105A. A first substrate 10 with a first cavity 110a is formed above the first interdigital transducer 103A and the second interdigital transducer 105A, and a through hole penetrating the first substrate 10 is formed on the second substrate 20 as a carrier , The through hole includes a first through hole 140 and a second through hole 150, the first through hole 140 extends to the first interdigital transducer 103A, the second through hole 150 extends to the second interdigital transducer 105A, subsequent processes It is similar to Embodiment 2, and will not be repeated here.

The embodiment of the present invention overcomes the difficulty of manufacturing matching capacitors and inductors on a device with a cavity and a functional unit (acoustic resonator unit) on the cavity. The manufacturing of the capacitor and the inductor is compatible with the manufacturing of the thin-film acoustic wave filter Process, and use the conductive layer process required for TSV through-hole connection to form all or part of the capacitor/inductance. No additional process is required to achieve functional integration, eliminating the PCB board and the high cost of the packaging process, and Achieve reduction in device thickness.

It should be noted that the various embodiments in this specification are described in a related manner, and the same or similar parts between the various embodiments can be referred to each other. Each embodiment focuses on the differences from other embodiments. . In particular, for method embodiment 3, since it is basically similar to embodiment 2, the description is relatively simple, and for related parts, please refer to the part of the description of embodiment 2.

The foregoing description is only a description of the preferred embodiments of the present invention, and does not limit the scope of the present invention in any way. Any changes or modifications made by a person of ordinary skill in the field of the present invention based on the foregoing disclosure shall fall within the protection scope of the claims.

Claims (20)

1. A thin-film acoustic wave filter is characterized in that it comprises:

   A first substrate, the first substrate including a first surface and a second surface opposed to each other;

   The first surface is provided with a first cavity;

   The acoustic wave resonator unit is arranged on the first substrate and covers the first cavity. The acoustic wave resonator unit includes a first electrode, a piezoelectric layer, and a second electrode; wherein the first electrode and the The second electrodes are respectively disposed on two opposite surfaces of the piezoelectric layer; or, the first electrode and the second electrode are both disposed on the side of the piezoelectric layer facing the first cavity, And relatively set;

   A first through hole is provided outside the first cavity, penetrates the first substrate, and extends to the first electrode;

   A second through hole is provided outside the first cavity, penetrates the first substrate, and extends to the second electrode;

   A conductive layer covering the inner walls of the first through hole and the second through hole and the second surface of the first substrate;

   The inductor and/or the capacitor are located on the second surface side of the first substrate.
2. 8. The thin-film acoustic wave filter according to claim 1, wherein the inductor and/or the capacitor include part of the conductive layer.
3. The thin film acoustic wave filter of claim 1, wherein the first substrate comprises a first substrate and a supporting layer, and the first substrate and the supporting layer are bonded by a bonding layer, so The first cavity is provided in the support layer.
4. The thin-film acoustic wave filter according to claim 1, wherein the capacitor comprises a first electrode plate and a second electrode plate arranged oppositely, and the first electrode plate and the second electrode plate are perpendicular to the The surface of the first substrate is or is parallel to the surface of the first substrate, and an insulating layer is provided between the first electrode plate and the second electrode plate.
5. 8. The thin-film acoustic wave filter according to claim 1, wherein the inductor and/or capacitor are arranged in a peripheral area of the first cavity.
6. The thin film acoustic wave filter of claim 1, wherein the inductor comprises a single-layer inductor or a multilayer inductor.
7. The thin film acoustic wave filter according to claim 1, wherein the thin film acoustic wave filter further comprises a cover layer disposed on the side of the acoustic wave resonator unit opposite to the first cavity, and the A second cavity is formed between the capping layer and the acoustic wave resonator unit.
8. 8. The thin film acoustic wave filter according to claim 7, further comprising: a first micro device, the first micro device being located on the capping layer;

   The electrical connection structure connects the first micro-device and electrically leads the first micro-device.
9. The thin-film acoustic wave filter according to claim 1, wherein the thin-film acoustic wave filter further comprises a second substrate, and the acoustic wave resonator unit is disposed on the side opposite to the first cavity. On the second substrate, a Bragg reflective layer is provided in the second substrate.
10. The thin-film acoustic wave filter of claim 1, wherein the thin-film acoustic wave filter is a surface acoustic wave filter, and the first electrode and the second electrode are a first interdigital transducer and a second interdigital transducer. Interdigital transducer.
11. A method for manufacturing a thin-film acoustic wave filter, which is characterized in that it comprises:

    Forming an acoustic wave resonator unit, the acoustic wave resonator unit including a piezoelectric layer, and a resonant electrode on the surface of the piezoelectric layer;

    Forming a first substrate with a first cavity on the surface of the piezoelectric layer, the first cavity is open on one side, and the opening faces the resonance electrode;

    Under a preset temperature and pressure: forming a through hole penetrating the first substrate on the periphery of the first cavity, the through hole extending to the resonance electrode;

    Forming a metal plating layer to cover the inner wall of the through hole and the surface of the first substrate;

    The metal plating layer is patterned to form a conductive layer and an inductor and/or a capacitor.
12. 11. The method for manufacturing a thin-film acoustic wave filter according to claim 11, wherein both ends of the inductor and/or capacitor are electrically connected to the first electrode and the second electrode through the conductive layer, respectively.
13. The method for manufacturing a thin-film acoustic wave filter according to claim 11, wherein the capacitor comprises a first electrode plate and a second electrode plate arranged in parallel, and the first electrode plate is perpendicular to the first substrate, Forming the capacitor includes:

    The metal plating layer is patterned to form an insulating trench penetrating the metal plating layer, and an insulating dielectric material is filled in the insulating trench to form the first electrode plate and the insulating trench that are formed by the metal plating layer and are insulated from each other. The second plate.
14. The method for manufacturing a thin-film acoustic wave filter according to claim 11, wherein the preset temperature is ≤ 500° C., and/or the pressure is ≤ two standard atmospheric pressures.
15. 11. The method of manufacturing a thin-film acoustic wave filter according to claim 11, wherein the step of forming a conductive layer and an inductor and/or a capacitor comprises:

    A first metal plating layer is formed, filling the first through holes and the second through holes and covering the surface of the first substrate, patterning the first metal plating layer, in the first through holes and the second through holes A conductive plug is formed in the hole, and the first plate of the capacitor;

    Forming a dielectric layer exposing the conductive plug on the first metal plating layer;

    A second metal plating layer is formed on the dielectric layer, and the second metal plating layer is patterned to form the conductive layer connected to the conductive plug and the second electrode plate of the capacitor.
16. 15. The method for manufacturing a thin film acoustic wave filter according to claim 15, wherein forming the inductor comprises: patterning the second metal plating layer to form the inductor.
17. The method for manufacturing a thin-film acoustic wave filter according to claim 11, wherein forming the metal plating layer comprises: setting the first through hole and the second through hole under a preset temperature and pressure environment. A metal seed layer is formed on the inner wall and the surface of the first substrate, and an electroplating material layer is formed on the surface of the seed layer through an electroplating process, the metal plating layer includes the seed layer and the electroplating material layer; or,

    The metal plating layer is formed on the inner wall of the first through hole and the second through hole and the surface of the first substrate through a physical vapor deposition process.
18. The method for manufacturing a thin-film acoustic wave filter according to claim 11, wherein the resonant electrode includes a first electrode and a second electrode located on different sides of the piezoelectric layer, and the step of forming an acoustic wave resonator unit includes:

    Providing a supporting substrate, on which the second electrode layer, the piezoelectric layer, and the first electrode layer are sequentially formed;

    Forming a supporting layer on the first electrode layer, and forming a first cavity penetrating the supporting layer in the supporting layer;

    Patterning the first electrode layer to form a first electrode;

    Bonding a first substrate on the supporting layer, the first substrate including the first substrate and the supporting layer;

    The carrier substrate is removed, and the second electrode layer is patterned to form a second electrode.
19. 19. The method for manufacturing a thin film acoustic wave filter according to claim 18, wherein after forming the second electrode and before forming the through hole, the method further comprises:

    A capping layer is provided on the second electrode side, and a second cavity is formed between the capping layer and the second electrode.
20. The method of manufacturing a thin-film acoustic wave filter according to claim 11, wherein the resonant electrode includes a first interdigital transducer and a second interdigital transducer located on the same side of the piezoelectric layer, forming The steps of the acoustic wave resonator unit include:

    A second substrate is provided, a piezoelectric layer and a conductive material layer are sequentially formed on the second substrate, and the conductive material layer is patterned to form the first interdigital transducer and the second interdigital transducer.