Patent Description:
Film Bulk Acoustic Resonators have a sandwiched structure including an electrode, a piezoelectric film and an electrode, where a layer of piezoelectric material is sandwiched between two metallic electrode layers. With an electrical signal being inputted between the two electrode layers, the input electrical signal is converted into a mechanical resonant wave through the piezoelectric film by using an inverse piezoelectric effect, and the mechanical resonant wave is converted into an electrical signal by using a piezoelectric effect to be outputted. For most of resonators, the acoustic wave is limited in a piezoelectric oscillation stack by using a cavity structure.

In the conventional technology, any one or more layers of a piezoelectric layer and a lower electrode are required to be etched to form a release hole for the sacrificial material to be released. However, etching causes damage to the piezoelectric layer and the lower electrode, and in a case that the sacrificial material is released, the damaged piezoelectric layer and the lower electrode easily collapse due to stress, thereby affecting the performance of the resonator. Patent document with publication No. <CIT> discloses a frame layer disposed over the release hole over filling an opening of the release hole. Patent document with publication No. <CIT> discloses a supporting layer which braces the lower electrode around the release hole. Patent publication <CIT> discloses a protection layer wrapping the whole resonant structure.

An acoustic resonator with a reinforcing structure and a method for manufacturing the same are provided according to the present disclosure, in order to solve the above technical problem that a piezoelectric oscillation stack above an edge of a cavity easily collapses and deforms with a poor mechanical strength.

An acoustic resonator with a reinforcing structure is provided according to a first aspect of the present disclosure. The acoustic resonator includes a substrate and a resonant functional layer formed above the substrate. The resonant functional layer includes a lower electrode, an upper electrode and a piezoelectric layer, where a cavity is formed between the lower electrode and the substrate; the upper electrode is arranged above the lower electrode; and the piezoelectric layer is arranged between the lower electrode and the upper electrode, where an opening passing through the piezoelectric layer is formed in a peripheral area of the piezoelectric layer, and part of the opening is in communication with the cavity. The reinforcing structure includes a reinforcing layer, and part of the reinforcing layer is formed on an upper surface and a side surface of the piezoelectric layer at an edge of the opening and is in contact with the edge of the opening to reinforce the resonant functional layer near the edge of the opening.

Moreover, an edge of the lower electrode is exposed in the opening and the reinforcing layer is in contact with part of the lower electrode exposed in the opening.

With the above technical solution, since the reinforcing structure includes the reinforcing layer, and part of the reinforcing layer is formed at the edge of the opening with being fitted to the edge, the reinforcing layer reinforces the piezoelectric layer and the lower electrode near the edge of the opening, which can reduce a change in stress of the piezoelectric layer and the lower electrode near the edge of the opening after the cavity is released, so that the piezoelectric layer and the lower electrode do not easily collapse due to stress, thereby improving the uniformity and yield of the acoustic resonator and ensuring the designed performance of a device.

With the above technical solution, since the edge of the lower electrode is exposed in the opening, and the reinforcing layer is in contact with part of the lower electrode exposed in the opening, the reinforcing layer and the lower electrode form an integrated structure to support the lower electrode.

The reinforcing layer extends onto an upper surface of the piezoelectric layer from the edge of the opening.

With the above technical solution, the reinforcing layer is further extended onto the upper surface of the piezoelectric layer, thereby forming a structure arranged on the piezoelectric layer, which further ensures the reinforcing effect of the reinforcing layer on the resonant functional layer near the opening.

In an embodiment, an extended part of the reinforcing layer is spanned on the piezoelectric layer on at least two sides of the opening.

With the above technical solution, since the extended part of the reinforcing layer is spanned on the piezoelectric layer on two sides of the opening, the reinforcing layer is supported on the piezoelectric layer on two sides of the opening, and then the reinforcing layer can better support the resonant functional layer near the edge of the opening.

In an embodiment, an extended part of the reinforcing layer extends, towards a center of the resonator, onto the piezoelectric layer from the edge of the opening.

With the above technical solution, since the extended part of the reinforcing layer extends, toward the center of the resonator, onto the piezoelectric layer from the edge of the opening, the piezoelectric layer in the central region of the resonator serves as a support area of the reinforcing layer, and then the reinforcing layer supports the resonant functional layer near the edge of the opening, so that the resonant functional layer does not easily collapse due to stress.

In an embodiment, the reinforcing layer covers the part of the lower electrode exposed in the opening.

With the above technical solution, since the reinforcing layer covers the part of the lower electrode exposed in the opening, the reinforcing layer reinforces the exposed part of the lower electrode, and then the lower electrode does not easily collapse due to stress.

In an embodiment, the reinforcing layer is made of a metallic material or a non-metallic material.

With the above technical solution, since the reinforcing layer mainly acts to reinforce, the reinforcing layer made of the metallic material can be better connected with the lower electrode, to form an integrated structure to a certain extent.

In an embodiment, the reinforcing layer is made of one or more of tungsten, iridium, molybdenum, titanium, chromium, copper, magnesium, silver, aluminium, gold or ruthenium.

With the above technical solution, the reinforcing layer made of the above single metal or alloy has high hardness, which allows the reinforcing layer to have a superior reinforcing effect, and the above material is preferably a material for the electrode. If the material of the reinforcing layer is the same as that of the electrode, the reinforcing layer and the upper electrode may be manufactured simultaneously in the same process step, to save costs.

In an embodiment, the reinforcing layer and the upper electrode are separated from each other without electrical connection between the reinforcing layer and the upper electrode.

With the above technical solution, in a case that the reinforcing layer is in contact with the lower electrode and there exists an electrical connection between the reinforcing layer and the upper electrode, the upper electrode and the lower electrode are directly connected, thereby rendering the acoustic resonator disabled.

In an embodiment, a gap at least greater than <NUM> microns exists between the reinforcing layer and an edge of the upper electrode.

With the above technical solution, the gap of <NUM> microns or more is provided between the piezoelectric layer and the upper electrode, which allows the upper electrode and the reinforcing layer to be separated completely, thereby not affecting the performance of the resonator.

In an embodiment, the reinforcing layer has a polygonal shape in cross-section in a direction parallel to a surface of the substrate.

With the above technical solution, since the reinforcing layer has a polygonal shape in the cross-section in the direction parallel to the surface of the substrate, the strength of overall mechanical structure of the resonant functional layer near the edge of the opening is further enhanced.

In an embodiment, at least one side of the cavity is provided with a release channel in communication with the cavity, a release hole is formed where the opening is in communication with the release channel, and the reinforcing layer surrounds the release hole.

With the above technical solution, the strength of overall mechanical structure around the release hole and the release channel is further reinforced by the reinforcing layer surrounding an aperture of the release hole.

In an embodiment, the reinforcing layer includes a laminated double-layered structure.

With the above technical solution, the reinforcing layer is formed in a laminated double-layered structure, which enhances the stability of the reinforcing layer, thereby improving the stability of the resonator.

In an embodiment, at least one layer of the double-layered structure is made of a material with high hardness.

With the above technical solution, one or both of the layers of the double-layered structure are made of the material with high hardness, which further enhances the stabilizing and supporting effects of the reinforcing layer.

In an embodiment, a passivation layer is covered on the reinforcing layer and the upper electrode, and the passivation layer covers a gap between the reinforcing layer and the upper electrode.

With the above technical solution, the reinforcing layer and the upper electrode may be protected by adding the passivation layer on the reinforcing layer.

In an embodiment, a projection of at least one corner of the release channel in a direction perpendicular to a surface of the substrate is obtuse or arc-shaped.

With the above technical solution, some or all of the corners of the release channel are obtuse or arc-shaped, which can reduce additional stresses generated in the corners, thereby reducing the effect of a change in stress of the corners on a change in stress of the piezoelectric layer.

A method for manufacturing an acoustic device with a reinforcing structure is further provided according to a second aspect of the present disclosure. The method includes:.

With the above technical solution, by manufacturing the upper electrode and the reinforcing layer above the piezoelectric layer and making the reinforcing layer cover the part of the lower electrode exposed in the opening, the reinforcing layer reinforces the piezoelectric layer and the lower electrode near the edge of the opening, which can reduce a change in stress of the piezoelectric layer and the lower electrode near the edge of the opening after the cavity is released, such that the piezoelectric layer and the lower electrode do not easily collapse due to stress, which improves the uniformity and yield of the acoustic resonator. With the manufacturing method, the upper electrode and the reinforcing layer are formed in an integrated structure, the manufactured reinforcing layer not only has an effect that the piezoelectric layer and the lower electrode do not easily collapse due to stress, but also has an effect that the reinforcing layer is manufactured in a simple and efficient way.

Part of an edge of the lower electrode is exposed in the opening and the reinforcing layer covers the edge of the lower electrode.

With the above technical solution, the reinforcing layer and the lower electrode form an integrated structure to support the lower electrode.

Part of the reinforcing layer further covers part of the piezoelectric layer.

With the above technical solution, the reinforcing layer may be further extended to cover the piezoelectric layer, thereby forming a structure arranged on the piezoelectric layer, which further ensures the reinforcing effect of the reinforcing layer on the resonant functional layer near the opening.

In an embodiment, the reinforcing layer and the upper electrode are formed simultaneously using a metallic material, and the reinforcing layer and the upper electrode are separated from each other.

With the above technical solution, since the reinforcing layer and the upper electrode are formed simultaneously, the reinforcing layer may be manufactured simultaneously while the upper electrode is manufactured for the acoustic resonator, thereby allowing the manufacturing process of the reinforcing layer to be simple and efficient.

An acoustic resonator with a reinforcing structure is provided according to the present disclosure. The reinforcing structure includes a reinforcing layer, part of the reinforcing layer is formed at the edge of the opening with being fitted to the edge, to reinforce the piezoelectric layer and the lower electrode near the edge of the opening, which can reduce a change in stress of the piezoelectric layer and the lower electrode near the edge of the opening after the cavity is released, so that the piezoelectric layer and the lower electrode do not easily collapse due to stress, thereby improving the uniformity and yield of the acoustic resonator and ensuring the designed performance of the device. A method for manufacturing an acoustic device with a reinforcing structure is further provided according to the present disclosure. With the method, the upper electrode and the reinforcing layer are formed simultaneously, and the manufactured reinforcing layer not only has an effect that the piezoelectric layer and the lower electrode do not easily collapse due to stress, but also has an effect that the reinforcing layer is manufactured in a simple and efficient way.

The accompanying drawings are included to provide a further understanding of the embodiments and are incorporated into and constitute a part of this specification. The drawings are used to illustrate embodiments and explain the principles of the present disclosure together with the description. In this way, many expected advantages of other embodiments and this embodiment may be easily recognized, since they may be better understood by referring to the following detailed description. The elements of the drawings are not necessarily to scale to each other. The same reference numerals refer to corresponding similar parts.

Description of reference numerals:
<NUM> substrate; <NUM> sacrificial layer; <NUM> lower electrode; <NUM> piezoelectric layer; <NUM> upper electrode; <NUM> reinforcing layer; <NUM> passivation layer; <NUM> release hole; <NUM> release channel; <NUM> cavity.

In order to enable objects, technical solutions and advantages of the present disclosure to be more clear, the present disclosure is further described in detailed below in conjunction with the drawings.

In the conventional technology, for a resonator structure as shown in <FIG>, a lower electrode <NUM> is raised upwards to form a cavity <NUM>, a piezoelectric layer <NUM> is etched to form a release hole <NUM>, and a release channel <NUM> extends outwards from the inside of the cavity <NUM>. In an area C shown in a dashed box, the electrode above the release channel <NUM> is completely suspended and unsupported, and an oscillation stack above the release channel <NUM> easily collapses and deforms with a poor mechanical strength, and the area C then affects the performance of an adjacent effective region, i.e. a region D, resulting in the damage to the uniformity of the performance of the piezoelectric film in the effective region. The acoustic resonator and the method for manufacturing the same are improved in the present disclosure.

<FIG> is a top view of an acoustic resonator with a reinforcing structure according to an embodiment of the present disclosure, and <FIG> is a cross-sectional view of an acoustic resonator along an A-A' direction in <FIG>. With reference to <FIG> in combination, the acoustic resonator specifically includes a substrate <NUM> and a resonant functional layer formed above the substrate <NUM>.

The resonant functional layer includes a lower electrode <NUM>, an upper electrode <NUM> and a piezoelectric layer <NUM>, where a cavity <NUM> is formed between the lower electrode <NUM> and the substrate <NUM>, the upper electrode <NUM> is arranged above the lower electrode <NUM>, the piezoelectric layer <NUM> is arranged between the lower electrode <NUM> and the upper electrode <NUM>, and openings <NUM> and <NUM> passing through the piezoelectric layer <NUM> are formed in a peripheral area of the piezoelectric layer <NUM>, and part of the opening is in communication with the cavity <NUM>. It can be seen part of the opening is in communication with the outside to form a release hole <NUM>. The acoustic resonator is further provided with a release channel <NUM>, and the release hole <NUM> is in communication with the cavity <NUM> through the release channel <NUM> to facilitate the release of a sacrificial material in the cavity <NUM>.

Part of a reinforcing layer <NUM> is formed at an edge of the opening <NUM> with being fitted to the edge, to reinforce the resonant functional layer near the edge of the opening <NUM>. In an specific example, the reinforcing layer <NUM> reinforces the piezoelectric layer <NUM> and the lower electrode <NUM> near the edge of the opening <NUM>, which can reduce a change in stress of the piezoelectric layer <NUM> and the lower electrode <NUM> near the edge of the opening <NUM> after the cavity <NUM> is released, so that the piezoelectric layer <NUM> and the lower electrode <NUM> do not easily collapse due to stress, thereby improving the uniformity and yield of the acoustic resonator.

An edge of the lower electrode <NUM> is exposed in the opening <NUM> and the reinforcing layer <NUM> is in contact with part of the lower electrode <NUM> exposed in the opening <NUM>. Furthermore, the reinforcing layer <NUM> covers the part, exposed in the opening <NUM>, of the lower electrode <NUM>. Since the edge of the lower electrode <NUM> is exposed in the opening <NUM> and the reinforcing layer <NUM> is in contact with the part of the lower electrode <NUM> exposed in the opening <NUM>, the reinforcing layer <NUM> and the lower electrode <NUM> form an integrated structure to support the lower electrode <NUM>. Furthermore, since the reinforcing layer <NUM> covers the part, exposed in the opening <NUM>, of the lower electrode <NUM>, the reinforcing layer <NUM> reinforces the part of the lower electrode <NUM> exposed in the opening <NUM>, such that the lower electrode <NUM> does not easily collapse due to stress.

In addition, as can be seen in <FIG>, part of the reinforcing layer <NUM> (together with the lower electrode <NUM>) substantially forms an upper surface of the release channel <NUM>. As a result, an opening of an edge of an effective resonant region of each of the lower electrode <NUM> and the piezoelectric layer <NUM> is reinforced by the reinforcing layer <NUM>, thereby significantly reducing the risk of collapse.

The reinforcing layer <NUM> and the upper electrode <NUM> are separated from each other without an electrical connection therebetween. In a case that the reinforcing layer <NUM> is in contact with the lower electrode <NUM> and there exists an electrical connection between the reinforcing layer <NUM> and the upper electrode <NUM>, the upper electrode <NUM> and the lower electrode <NUM> are directly connected, thereby rendering the acoustic resonator disabled. In a specific example, a gap greater than <NUM> microns exists between the reinforcing layer <NUM> and an edge of the upper electrode <NUM>, which allows the upper electrode <NUM> and the reinforcing layer <NUM> to be separated completely, thereby not affecting the performance of the resonator.

In a specific embodiment, as shown in <FIG>, an extended part of the reinforcing layer <NUM> may extend, towards a center of the resonator, onto the piezoelectric layer <NUM> from the edge of the opening <NUM>, and the reinforcing layer <NUM> extends onto the upper surface of the piezoelectric layer <NUM> from the edge of the opening <NUM>, thereby forming a structure arranged on the piezoelectric layer <NUM>, which further ensures the reinforcing effect of the reinforcing layer <NUM> on the resonant functional layer near the opening. Since the stress on the upper surface of the piezoelectric layer <NUM> varies to a relatively large extent after the cavity <NUM> is released, the reinforcing layer <NUM> extends onto the upper surface of the piezoelectric layer <NUM> from the edge of the opening <NUM>, which further allows the piezoelectric layer <NUM> to not easily collapse due to stress.

In a specific embodiment, as shown in <FIG>, the extended part of the reinforcing layer <NUM> is spanned on the piezoelectric layer <NUM> on two sides of the opening <NUM>, so that the reinforcing layer <NUM> is supported on the piezoelectric layer <NUM> on two sides of the opening <NUM>, which further allows the reinforcing layer <NUM> to support the resonant functional layer near the edge of the opening <NUM> and further allows the resonant functional layer to not easily collapse due to stress.

In an example which is not part of the claimed invention, in a case that the extended part is spanned on the piezoelectric layer <NUM> on two sides of the opening <NUM> as shown in <FIG>, the reinforcing layer <NUM> may only be in contact with the lower electrode <NUM>, and not contact with the piezoelectric layer <NUM> at a part (i.e. a right-side long edge part of a grey area <NUM> shown in <FIG> or a part corresponding to the right side of the opening <NUM> shown in <FIG>) extending towards the center of the resonator (as shown in enlarged <FIG>). Alternatively, the reinforcing layer <NUM> may be in contact with the lower electrode <NUM> and fitted to the piezoelectric layer <NUM> at the part extending towards the center of the resonator (as shown in enlarged <FIG>).

In different embodiments, as shown in <FIG> and <FIG>, the reinforcing layer <NUM> may only be in contact with the piezoelectric layer <NUM> and the lower electrode <NUM> and is not spanned. In this case, the reinforcing layer <NUM> preferably creeps (extends) inwards onto the piezoelectric layer <NUM> in the effective resonant region, as shown in <FIG>.

In a further embodiment, the reinforcing layer <NUM> is made of a metallic material. Since the reinforcing layer <NUM> mainly acts to reinforce, the reinforcing layer <NUM> made of a metallic material has a better reinforcing effect. It is important that the metallic reinforcing layer <NUM> and the lower electrode <NUM> may be formed into an integrated structure, the electric field between the reinforcing layer <NUM> and the lower electrode <NUM> is equal and therefore there is no potential difference therebetween, and a piezoelectric effect is not produced in a part "sandwiching" the piezoelectric layer <NUM>, which ensures that the designs or structures of the reinforcing layer <NUM> do not introduce parasitic effects and spurious signals, thereby not affecting the performance of a resonator device.

In a further embodiment, the reinforcing layer <NUM> is made of one or more of tungsten, iridium, molybdenum, titanium, chromium, copper, magnesium, silver, aluminium, gold or ruthenium, and the reinforcing layer <NUM> made of the above single metal or alloy has high hardness, which allows the reinforcing layer <NUM> to have a superior reinforcing effect. The above material is preferably a material for the electrode. If the material of the reinforcing layer <NUM> is the same as that of the electrode, the reinforcing layer <NUM> and the upper electrode <NUM> may be manufactured simultaneously in the same process step, to save costs.

In a further embodiment, as shown in <FIG>, the reinforcing layer <NUM> has a polygonal shape in cross-section in a direction parallel to a surface of the substrate <NUM>. since the reinforcing layer <NUM> has a polygonal shape in the cross-section in the direction parallel to the surface of the substrate <NUM>, the strength of overall mechanical structure of the resonant functional layer near the edge of the opening <NUM> is further enhanced.

In a further embodiment, as shown in <FIG>, a release hole <NUM> is formed where the opening <NUM> is in communication with the release channel <NUM> and the cavity <NUM>, and the reinforcing layer <NUM> may surround the release hole <NUM>. Specifically, a central part of the annular-shaped reinforcing layer <NUM> is provided with a hollow portion, which is arranged above the release hole <NUM>, and the reinforcing layer <NUM> surrounds an entire peripheral area of the release hole <NUM> to form an annular shape, thereby realizing the reinforcement of the reinforcing layer <NUM> in the entire peripheral area of the release hole <NUM>.

In a further embodiment, the reinforcing layer <NUM> includes a laminated double-layered structure and at least one layer of the double-layered structure is made of a material with high hardness. In a case that the reinforcing layer <NUM> is made of the same material as that of the electrodes, the reinforcing layer <NUM> is highly conductive. In a case that the reinforcing layer <NUM> does not have high hardness, a layer of structure made of a material with high hardness is added to further enhance the stabilizing and supporting effects of the reinforcing layer <NUM>. In a specific example, as shown in <FIG>, the reinforcing layer <NUM> includes a double-layered structure of high hardness material layer 106a and high conductivity material layer 106a' laminated each other, and the double-layered structure is made of different materials, where the material for the high hardness material layer 106a is preferably tungsten, iridium, molybdenum, titanium, chromium, copper, magnesium, silver, aluminium, gold or the above metals or alloys thereof, or the like. The material for the high conductivity material layer 106a' is preferably silver, copper, gold, aluminium, magnesium, molybdenum, iridium, tungsten, chromium, titanium, or the like, or an alloy thereof or the like. In other embodiments, the reinforcing layer <NUM> may be made of non-metallic materials, which are not particularly limited here.

In a further embodiment, as shown in <FIG>, a passivation layer <NUM> covers the reinforcing layer <NUM> and the upper electrode <NUM>, and the passivation layer <NUM> covers a gap between the reinforcing layer <NUM> and the upper electrode <NUM>. The passivation layer <NUM> protects a surface of the resonator from oxidation and increases the service life of the resonator. The addition of the passivation layer <NUM> on the reinforcing layer <NUM> also serves to enhance the stabilizing and supporting effects of the reinforcing layer <NUM>. In this case, there is no need to form other materials on the reinforcing layer <NUM>, saving process steps. The passivation layer <NUM> may be not added on the reinforcing layer <NUM> in a case that the reinforcing layer <NUM> has a good stabilizing and supporting effects.

In a further embodiment, with reference to <FIG>, corners of the release hole <NUM> are obtuse at the edge near the peripheral area of the resonator. With the corners of the release hole <NUM> at the edge near the peripheral area of the resonator being obtuse additional stress generated in the corners may be reduced, thereby reducing the effect of a change in stress of the corners on a change in stress of the piezoelectric layer <NUM>.

In a further embodiment, with reference to <FIG>, corners of the release channel <NUM> are arc-shaped at the edge near the peripheral area of the resonator. With the corners of the release channel <NUM> at the edge near the peripheral area of the resonator being arc-shaped, the additional stress generated in the corners may be reduced, thereby reducing the effect of a change in stress of the corners on a change in stress of the piezoelectric layer <NUM>.

The above embodiment also has the following effects. In the conventional technology, the release hole is generally arranged on the piezoelectric layer, and the release hole is etched when being released to be in communication with the sacrificial layer. As shown in <FIG>, a patent with a publication number <CIT> refers to that a distance S1 of a release hole <NUM> from a lower electrode is equal to about <NUM> micron to <NUM> microns, and since a dielectric constant of air is much lower than a dielectric constant of the piezoelectric material, a path of electrostatic breakdown is more likely to extend along the release hole <NUM>. That is, the cross-section of the piezoelectric layer is exposed after the piezoelectric layer is etched, and the exposed cross-section becomes a weakest point of the material susceptible to electrostatic breakdown since the etching causes the crystal structure of the material to be fractured at the cross-section. As a result, under certain circumstances, charges between the upper electrode and the lower electrode may be conducted through the air, causing the piezoelectric layer to be broken through by high voltage static electricity (e.g. 3000V) from the fractured cross-section, resulting in a device failure, i.e. the resonator's performance of anti-electrostatic breakdown, which can affect the yield control and operating life of device in a production process. In the present technical solution, as shown in <FIG>, the lower electrode <NUM> and the reinforcing layer <NUM> form a "sandwiching" effect on the piezoelectric layer <NUM> at the end of a resonant region, with the reinforcing layer <NUM> covering the cross-section of the piezoelectric layer <NUM> from above the piezoelectric layer <NUM> and connecting to the lower electrode <NUM>, thus protecting the entire cross-section. The piezoelectric layer <NUM> between the reinforcing layer <NUM> and the upper electrode <NUM> has no risk of electrostatic breakdown since there is no fractured cross-section.

The reinforcing layer structure in the present disclosure is also applicable to any structure with a release hole in the conventional technology. By way of example, as shown in <FIG>, in a patent with a publication number <CIT>, a resonator includes a substrate <NUM>, a cavity <NUM>, a lower electrode <NUM>, a piezoelectric layer <NUM>, an upper electrode <NUM>, a bridge portion <NUM> and a contact portion <NUM>. The cavity <NUM> of the resonator in practice is also formed by releasing a sacrificial material. The structure with a reinforcing layer being added is shown in <FIG>, where a release hole <NUM> passes through the piezoelectric layer <NUM> to be in communication with a release channel <NUM>, allowing the sacrificial material to be released. The addition of the reinforcing layer <NUM> to the structure of the conventional technology also reinforces the strength of the overall mechanical structure around the release hole and the release channel.

With reference to <FIG>, a method of manufacturing an acoustic device with a reinforcing structure is further provided according to an embodiment of the present disclosure. The manufacturing method includes steps S1 to S6.

In step S2, a sacrificial layer for forming a cavity is manufactured on the substrate.

In a specific embodiment, as shown in <FIG>, step S2 specifically includes the steps of: depositing a sacrificial material on the substrate <NUM>, patterning the sacrificial material to form a sacrificial layer <NUM>. In an example, CMP (chemical mechanical polishing) is performed on the sacrificial layer <NUM>. The material for the substrate <NUM> is preferably Si/sapphire/spinel or the like, and the material for the sacrificial layer <NUM> is preferably PSG (i.e. P-doped SiO<NUM>).

It will be appreciated that in different embodiments (not shown in the figures), it is also possible to manufacture the sacrificial layer, in which the cavity is to be formed, on the substrate <NUM> by firstly manufacturing a groove in the substrate <NUM> and then filling the groove using the sacrificial material.

In step S3, a lower electrode and a piezoelectric layer are formed in sequence on the substrate on which the sacrificial layer is formed.

In a specific embodiment, with reference to <FIG>, step S3 specifically includes the steps S31 to S32.

In step S31, a lower electrode <NUM> is manufactured on the sacrificial layer <NUM> by a sputtering, photolithography or etching process, where the material for the lower electrode <NUM> is preferably Mo, as shown in <FIG>.

In step S32, a piezoelectric layer <NUM> is grown on the lower electrode <NUM> such that the piezoelectric layer <NUM> covers the lower electrode <NUM>, the sacrificial layer <NUM> and the substrate <NUM>, as shown in <FIG>.

In step S4, an opening is formed in the piezoelectric layer to expose part of the lower electrode such that the opening is in communication with the sacrificial layer.

In a specific embodiment, with reference to <FIG>, step S4 specifically includes: etching the piezoelectric layer <NUM> to expose part of an edge of the lower electrode <NUM> and part of the sacrificial layer <NUM> near the edge of the lower electrode <NUM> to form openings <NUM> and <NUM>, where a release hole <NUM> is formed where each of the openings is in communication with the sacrificial layer <NUM>, and part of the edge of the lower electrode <NUM> is exposed in the opening <NUM>.

In step S5, an upper electrode and a reinforcing layer are manufactured on the piezoelectric layer, part of the reinforcing layer is formed at the edge of the opening with being fitted to the edge, to reinforce the resonant functional layer near the edge of the opening.

In a specific embodiment, with reference to <FIG>, step S5 specifically includes steps S51 to S52.

In step S51, an electrode material layer 105A is manufactured on the piezoelectric layer <NUM> by a sputtering, photolithography or etching process, such that the electrode material layer 105A covers the part of the lower electrode <NUM> and the part of the sacrificial layer <NUM> that is exposed in the piezoelectric layer <NUM>, as shown in <FIG>.

In step S52, the part of the electrode material layer 105A which extends, towards an effective region of the acoustic resonator, from the edge of the opening <NUM> to a position above the piezoelectric layer <NUM> is separated from the remaining part of the electrode material layer 105A, to form the reinforcing layer <NUM>.

As shown in <FIG>, the reinforcing layer <NUM> covers the part of the lower electrode <NUM> exposed in the opening <NUM> and reinforces the piezoelectric layer <NUM> near the opening <NUM>, part of the reinforcing layer <NUM> further covers part of the piezoelectric layer <NUM>, and the part of the electrode material layer 105A being retained severs as the upper electrode <NUM>. The upper electrode <NUM> and the reinforcing layer <NUM> are preferably spaced greater than <NUM> microns apart to ensure that there is no risk of electrical connection therebetween.

In step S6, the sacrificial layer is released to form the cavity.

In a specific embodiment, as shown in <FIG>, step S6 specifically includes the step of releasing the sacrificial layer <NUM> by means of, for example, a hydrofluoric acid etchant, in order to expose the cavity <NUM>.

Claim 1:
An acoustic resonator with a reinforcing structure, comprising:
a substrate (<NUM>); and
a resonant functional layer formed above the substrate (<NUM>), the resonant functional layer comprising:
a lower electrode (<NUM>), wherein a cavity (<NUM>) is formed between the lower electrode (<NUM>) and the substrate (<NUM>);
an upper electrode (<NUM>), arranged above the lower electrode (<NUM>); and
a piezoelectric layer (<NUM>), arranged between the lower electrode (<NUM>) and the upper electrode (<NUM>), wherein an opening (<NUM>) passing through the piezoelectric layer is formed in a peripheral area of the piezoelectric layer (<NUM>), and part of the opening (<NUM>) is in communication with the cavity (<NUM>);
wherein the reinforcing structure comprises a reinforcing layer (<NUM>), and part of the reinforcing layer (<NUM>) is formed on an upper surface and a side surface of the piezoelectric layer (<NUM>) at an edge of the opening (<NUM>) and is in contact with the edge of the opening (<NUM>) to reinforce the resonant functional layer (<NUM>) near the edge of the opening (<NUM>); and
wherein an edge of the lower electrode (<NUM>) is exposed in the opening (<NUM>), and the reinforcing layer (<NUM>) is in contact with part of the lower electrode (<NUM>) exposed in the opening.