TW202112066A - Bulk-acoustic wave resonator - Google Patents

Abstract

A bulk-acoustic wave resonator includes: a resonator comprising a central portion in which a first electrode, a piezoelectric layer, and a second electrode are sequentially stacked on a substrate, and an extension portion disposed along a periphery of the central portion; and an insertion layer disposed below the piezoelectric layer in the extension portion to raise the piezoelectric layer. The insertion layer may have a first inclined surface formed along a side surface facing the central portion, and the first electrode may have a second inclined surface extending from a lower end of the first inclined surface of the insertion layer.

Description

Integral Acoustic Resonator

The present invention relates to a bulk acoustic wave resonator.

According to the miniaturization trend of wireless communication devices, there is an increasing demand for the miniaturization of high-frequency component technology. For example, a bulk acoustic wave (BAW) filter using semiconductor thin film wafer manufacturing technology can be used.

A bulk acoustic wave (BAW) resonator is a thin-film element that is implemented as a filter by depositing piezoelectric dielectric materials on silicon wafers and semiconductor substrates and using its piezoelectric features to generate resonance.

Recently, there has been increasing interest in the technology of 5G communication, and the development of technologies that can be implemented in candidate frequency bands is being actively carried out.

However, in the case of 5G communication using the Sub 6 GHz (4 GHz to 6 GHz) frequency band, as the bandwidth increases and the communication distance decreases, the strength or power of the signal can be increased. In addition, as the frequency increases, the loss generated in the piezoelectric layer or resonator may increase.

Therefore, there is a need for a bulk acoustic wave resonator that can minimize the energy leakage in the resonator.

The above information is presented only as background information to assist the understanding of the present invention. No judgment and statement regarding any of the foregoing may be applicable to the prior art regarding the present invention.

This content of the invention is provided to introduce in a simplified form a series of concepts that are further described in the embodiments below. This summary of the invention is not intended to identify the key features or basic features of the claimed subject matter, nor is it intended to be used as an aid in determining the scope of the claimed subject matter.

In a general aspect, a bulk acoustic wave resonator includes: a resonator including a central portion in which a first electrode, a piezoelectric layer, and a second electrode are sequentially stacked on a substrate and arranged along the periphery of the central portion The extension portion; and the insertion layer, which is disposed under the piezoelectric layer in the extension portion to raise the piezoelectric layer. The insertion layer has a first inclined surface formed facing the side surface of the central portion, and the first electrode has a second inclined surface extending from the lower end of the first inclined surface of the insertion layer.

The inclination angle of the second inclined surface may be lower than that of the first inclined surface.

The first electrode may include a thickness of a lower end portion of the second inclined surface that is smaller than a thickness of an upper end portion of the second inclined surface.

The second inclined surface may be arranged in the central part.

The first electrode may be an upper surface in the central part and an upper surface in the extension part, and the upper surfaces are arranged on different planes.

The bulk acoustic wave resonator may further include a diaphragm layer disposed under the first electrode and the insertion layer to support the resonator and a cavity separating the resonator from the substrate.

The third inclined surface may be arranged along the end of the first electrode, and the membrane layer may have a fourth inclined surface extending from the lower end of the third inclined surface.

The fourth inclined surface may include a lower inclination angle than the third inclined surface.

The end of the insertion layer can contact the third inclined surface of the first electrode.

The insertion layer may be thicker than the first electrode.

The bulk acoustic wave resonator may further include a cover that accommodates the resonator and is bonded to the substrate.

The bulk acoustic wave resonator may further include a plurality of via holes configured to penetrate the cover, and a plurality of connecting conductors arranged in the plurality of via holes to electrically connect the first electrode and the second electrode to the outside.

The bulk acoustic wave resonator may further include external electrodes bonded to a plurality of connection conductors exposed on the external surface of the cover.

The bulk acoustic wave resonator may further include a first metal layer and a second metal layer. The first metal layer and the second metal layer are disposed outside the resonator and are respectively connected to the first electrode and the second electrode. The plurality of connecting conductors may be electrically connected to the first electrode and the second electrode through the first metal layer and the second metal layer, respectively.

The piezoelectric layer may include an inclined portion arranged on the first inclined surface, and the end of the second electrode may be arranged on the inclined portion of the piezoelectric layer.

In another general aspect, a bulk acoustic wave resonator includes: a resonator including a central portion in which a first electrode, a piezoelectric layer, and a second electrode are sequentially stacked on a substrate and a periphery along the central portion Configured extension portion; and an insertion layer disposed under the piezoelectric layer in the extension portion to raise the piezoelectric layer, wherein the thickness of the first electrode in the central portion is smaller than the thickness in the extension portion.

In another general aspect, the bulk acoustic wave resonator includes: a central portion including a first electrode, a piezoelectric layer, and a second electrode stacked on a substrate in sequence; and an extension arranged along the periphery of the central portion Part, which includes a first electrode, an insertion layer, a piezoelectric layer, and a second electrode sequentially stacked on the substrate, wherein the first electrode includes a first reflective interface in the central part.

The first reflective interface may include an inclined surface extending from the lower end of the insertion layer toward the central portion.

The bulk acoustic resonator may further include a diaphragm layer disposed under the first electrode to support the first electrode and a cavity separating the first electrode from the substrate, wherein the diaphragm layer may include a second reflective interface in the extension portion.

The second reflective interface may include an inclined surface extending away from the central portion from the lower end of the first electrode.

Other features and aspects will be apparent from the following embodiments, drawings, and scope of patent application.

The following detailed description is provided to help readers gain a comprehensive understanding of the methods, devices and/or systems described in this article. However, after understanding the present invention, various changes, modifications and equivalents of the methods, devices and/or systems described herein will be apparent. For example, the order of operations described herein is only an example, and is not limited to the examples set forth herein, but in addition to operations that must occur in a certain order, the order of operations can be changed, as will be apparent after understanding the present invention. Moreover, for the purpose of improving clarity and conciseness, the description of the features known in the art may be omitted.

The features described herein may be embodied in different forms, and the features should not be construed as being limited to the examples described herein. In fact, only the examples described herein are provided to illustrate some of the many possible ways of implementing the methods, devices and/or systems described herein, which will be obvious after understanding the present invention.

Throughout this specification, when an element such as a layer, region, or substrate is described as being "on another element," "connected to another element," or "coupled to another element," the element may be directly "On another element", "connected to another element" or "coupled to another element", or one or more other elements may be intervened in between. In contrast, when an element is described as being "directly above another element," "directly connected to another element," or "directly coupled to another element," other elements may not be intervened therebetween. As used herein, a "portion" of an element may include the entire element or less than the entire element.

As used herein, the term "and/or" includes any one and any combination of any two or more related listed items; likewise, "at least one of" includes any two or more Any one and any combination of the relevant listed items.

Although terms such as "first", "second", and "third" may be used herein to describe various members, components, regions, layers or sections, these members, components, regions, layers or sections Not limited to these terms. In fact, these terms are only used to distinguish one component, component, region, layer or section from another component, component, region, layer or section. Therefore, without departing from the teachings of the examples, the first member, component, region, layer or section referred to in the examples described herein can also be referred to as a second member, component, region, layer or section segment.

For ease of description, spatially relative terms (such as "above", "upper", "below", "lower" and the like may be used herein to describe an element as shown in the figures and The relationship between another element. In addition to the orientations depicted in the figures, these spatial relative terms are intended to cover different orientations of the device in use or operation. For example, if the device in the figure is turned over, the element described as "above" or "upper" with respect to another element will then be described as "below" or "below" with respect to another element ". Therefore, the term "above" encompasses both an upper and a lower orientation depending on the spatial orientation of the device. The device can also be oriented in other ways (rotated by 90 degrees or in other orientations), and the spatial relative terms used herein are explained accordingly.

The terms used herein are only used to describe various examples, and are not used to limit the present invention. Unless the context clearly indicates otherwise, the articles "a/an" and "the" are also intended to include plural forms. The terms "including", "including" and "having" designate the presence of stated features, numbers, operations, components, elements, and/or combinations thereof, but do not exclude the presence or addition of one or more other features, numbers, operations, Components, elements and/or combinations thereof.

As will be apparent after understanding the present invention, the features of the examples described herein can be combined in various ways. In addition, although the examples described herein have multiple configurations, as will be apparent after understanding the present invention, other configurations are also possible.

In this context, it should be noted that the use of the term "may" with respect to examples (for example, with regard to what examples an example may include or implement) means that there is at least one example in which this feature is included or implemented, but all examples are not limited thereto.

One aspect of the present invention is to provide a bulk acoustic resonator capable of reducing energy leakage.

FIG. 1 is a plan view of an acoustic wave resonator according to an embodiment of the present invention, and FIG. 2 is a cross-sectional view taken along the line II′ of FIG. 1. 3 is a cross-sectional view taken along the line II-II' of FIG. 1, FIG. 4 is a cross-sectional view taken along the line III-III' of FIG. 1, and FIG. 5 is an enlarged view of a part A of FIG. 2.

1 to 5, the acoustic wave resonator 100 according to an embodiment of the present invention may be a bulk-acoustic wave (BAW) resonator, and may include a substrate 110, a sacrificial layer 140, a resonator 120, and an insertion layer 170 .

The substrate 110 may be a silicon substrate. For example, a silicon wafer can be used as the substrate 110, or a silicon on insulator (SOI) type substrate can be used.

The insulating layer 115 may be provided on the upper surface of the substrate 110 to electrically isolate the substrate 110 from the resonator 120. In addition, the insulating layer 115 prevents the substrate 110 from being etched by the etching gas when the cavity C is formed in the manufacturing process of the acoustic resonator.

In this case, the insulating layer 115 may be _{formed of at least one of silicon dioxide (SiO 2} ), silicon nitride (Si ₃ N ₄ ), aluminum oxide (Al ₂ O ₃ ), and aluminum nitride (AlN), and It can be formed by any process of chemical vapor deposition, RF magnetron sputtering and evaporation.

The sacrificial layer 140 is formed on the insulating layer 115, and the cavity C and the etching stop portion 145 are disposed in the sacrificial layer 140.

The cavity C is formed as a blank space, and may be formed by removing a part of the sacrificial layer 140.

When the cavity C is formed in the sacrificial layer 140, the resonator 120 formed above the sacrificial layer 140 may be formed completely flat.

The etching stop portion 145 is arranged along the boundary of the cavity C. The etching stop portion 145 is provided to prevent the execution of the etching from exceeding the cavity area during the process of forming the cavity C.

The diaphragm layer 150 is formed on the sacrificial layer 140 and forms the upper surface of the cavity C. Therefore, the diaphragm layer 150 is also formed of a material that is not easily removed during the process of forming the cavity C.

For example, when a halide etching gas such as fluorine (F), chlorine (Cl) or the like is used to remove a part of the sacrificial layer 140 (for example, the cavity region), the diaphragm layer 150 can be etched with Made of materials with low gas reactivity. In this case, the diaphragm layer 150 may include at least one of _{silicon dioxide (SiO 2} ) and silicon nitride (Si ₃ N _{4 ).}

The membrane layer 150 may contain magnesium oxide (MgO), zirconium oxide (ZrO2), aluminum nitride (AlN), lead zirconate titanate (PZT), gallium arsenide (GaAs), hafnium oxide (HfO ₂ ) and aluminum oxide ( A dielectric layer of at least one of Al ₂ O ₃ ), titanium oxide (TiO ₂ ), and zinc oxide (ZnO) and a dielectric layer containing aluminum (Al), nickel (Ni), chromium (Cr), platinum (Pt), and gallium (Ga) and hafnium (Hf) are made of a metal layer of at least one material. However, the present invention is not limited to this.

The resonator 120 includes a first electrode 121, a piezoelectric layer 123 and a second electrode 125. The resonator 120 is configured such that the first electrode 121, the piezoelectric layer 123, and the second electrode 125 are sequentially stacked from the bottom. Therefore, the piezoelectric layer 123 in the resonator 120 is disposed between the first electrode 121 and the second electrode 125.

Since the resonator 120 is formed on the diaphragm layer 150, the diaphragm layer 150, the first electrode 121, the piezoelectric layer 123, and the second electrode 125 are sequentially stacked on the substrate 110 to form the resonator 120.

The resonator 120 can resonate the piezoelectric layer 123 according to the signals applied to the first electrode 121 and the second electrode 125 to generate a resonance frequency and an anti-resonance frequency.

The resonator 120 can be divided into: a central part S, in which the first electrode 121, the piezoelectric layer 123, and the second electrode 125 are stacked to be substantially flat; and an extension part E, in which the insertion layer 170 is inserted into the first electrode 121 and the pressure Between electrical layers 123.

The central part S is an area arranged at the center of the resonator 120, and the extension part E is an area arranged along the periphery of the central part S. Therefore, the extension portion E is an area extending outward from the central portion S, and refers to an area formed to have a continuous annular shape along the periphery of the central portion S. However, if necessary, the extension portion E may be configured to have a discontinuous ring shape, in which some areas are separated.

Therefore, as shown in FIG. 2, in the cross section of the resonator 120 cut to cross the central part S, the extension parts E are arranged at both ends of the central part S, respectively. The insertion layer 170 is disposed on both sides of the central part S in the extension part E, and the extension part E is disposed on both ends of the central part S.

The insertion layer 170 has an inclined surface L whose thickness becomes larger as the distance from the center portion S increases.

In the extension part E, the piezoelectric layer 123 and the second electrode 125 are disposed on the insertion layer 170. Therefore, the piezoelectric layer 123 and the second electrode 125 located in the extension portion E have inclined surfaces along the shape of the insertion layer 170.

In the embodiment of the present invention, the extension part E is included in the resonator 120, and therefore, resonance may occur in the extension part E. However, the present invention is not limited to this, and resonance may not exist in the extension E depending on the structure of the extension E, but the resonance may only be performed in the central part S.

The first electrode 121 and the second electrode 125 may be formed of a conductor, for example, may be formed of any of the following: gold, molybdenum, ruthenium, iridium, aluminum, platinum, titanium, tungsten, palladium, tantalum, chromium, nickel, or one containing at least one of them Metal, but not limited to this.

In the resonator 120, the first electrode 121 is formed to have an area larger than the second electrode 125, and the first metal layer 180 is disposed on the first electrode 121 along the periphery of the first electrode 121. Therefore, the first metal layer 180 may be configured to be separated from the second electrode 125 by a predetermined distance, and may be configured to surround the resonator 120.

Since the first electrode 121 is disposed on the diaphragm layer 150, the first electrode 121 is formed flat as a whole. Since the second electrode 125 is disposed on the piezoelectric layer 123, a curve corresponding to the shape of the piezoelectric layer 123 can be formed.

The first electrode 121 can be used as one of an input electrode and an output electrode for inputting and outputting electrical signals such as radio frequency (RF) signals.

The second electrode 125 is completely disposed in the central portion S and partially disposed in the extension portion E. Therefore, the second electrode 125 can be divided into a part arranged on the piezoelectric part 123a of the piezoelectric layer 123, which will be described later, and a part arranged on the curved part 123b of the piezoelectric layer 123.

More specifically, in the embodiment of the present invention, the second electrode 125 is configured to cover the entire piezoelectric portion 123 a and a part of the inclined portion 1231 of the piezoelectric layer 123. Therefore, the second electrode (the second electrode 125a in FIG. 4) disposed in the extension portion E is formed to have an area smaller than the inclined surface of the inclined portion 1231, and the second electrode 125 in the resonator 120 is formed to have an area smaller than that of the piezoelectric layer 123.

Therefore, as illustrated in FIG. 2, in the cross section where the resonator 120 is cut to cross the central portion S, the end of the second electrode 125 is disposed in the extension portion E. In addition, at least a part of the end of the second electrode 125 arranged in the extension portion E is arranged to overlap the insertion layer 170. Here, “overlap” means that when the second electrode 125 is projected on the plane where the insertion layer 170 is arranged, the shape of the second electrode 125 projected on the plane overlaps the insertion layer 170.

The second electrode 125 may be used as one of an input electrode and an output electrode for inputting and outputting electrical signals such as radio frequency (RF) signals or the like. That is, when the first electrode 121 is used as an input electrode, the second electrode 125 may be used as an output electrode, and when the first electrode 121 is used as an output electrode, the second electrode 125 may be used as an input electrode.

As illustrated in FIG. 4, when the end of the second electrode 125 is positioned on the inclined portion 1231 of the piezoelectric layer 123 to be described later, the local structure of the acoustic impedance of the resonator 120 is formed from the sparseness of the central portion S. In the /dense/dense structure, the reflection interface at which the side wave is reflected inward from the resonator 120 increases. Therefore, since most of the side waves do not flow outward from the resonator, and are reflected and then flow into the interior of the resonator 120, the performance of the acoustic resonator can be improved.

The piezoelectric layer 123 is a part that converts electrical energy into mechanical energy in the form of elastic waves through a piezoelectric effect, and is formed on the first electrode 121 and the insertion layer 170 which will be described later.

As the material of the piezoelectric layer 123, zinc oxide (ZnO), aluminum nitride (AlN), doped aluminum nitride, lead zirconate titanate, quartz, and the like can be selectively used. In the case of doped aluminum nitride, it may further contain rare earth metals, transition metals or alkaline earth metals. The rare earth metal may include at least one of scandium (Sc), erbium (Er), yttrium (Y), and lanthanum (La). The transition metal may include at least one of hafnium (Hf), titanium (Ti), zirconium (Zr), tantalum (Ta), and niobium (Nb). In addition, the alkaline earth metal may contain magnesium (Mg).

In order to improve the piezoelectric properties, when the content of the element doped with aluminum nitride (AlN) is less than 0.1 at%, the piezoelectric properties higher than that of aluminum nitride (AlN) cannot be achieved. When the content of the element exceeds 30 atomic %, it is difficult to manufacture and control the composition for deposition, so that an uneven or undesirable crystalline phase can be formed.

Therefore, in the embodiment of the present invention, the content of the element doped with aluminum nitride (AlN) is in the range of 0.1 atomic% to 30 atomic %.

In the embodiment of the present invention, the piezoelectric layer is doped with scandium (Sc) in aluminum nitride (AlN). In this case, the piezoelectric constant can be increased to increase the K _t ^{2 of the} acoustic resonator. However, the configuration of the present invention is not limited to this.

The piezoelectric layer 123 according to the embodiment of the present invention includes a piezoelectric part 123a arranged in the central part S and a curved part 123b arranged in the extension part E.

The piezoelectric portion 123a is a portion directly stacked on the upper surface of the first electrode 121. Therefore, the piezoelectric portion 123a is inserted between the first electrode 121 and the second electrode 125 to form a flat shape together with the first electrode 121 and the second electrode 125.

The curved portion 123b can be understood as a region extending from the piezoelectric portion 123a to the outside and positioned in the extending portion E.

The bent portion 123b is disposed on the insertion layer 170 to be described later, and is formed in a shape in which the upper surface is raised along the shape of the insertion layer 170. Therefore, the piezoelectric layer 123 is bent at the boundary between the piezoelectric portion 123a and the bent portion 123b, and the bent portion 123b is raised corresponding to the thickness and shape of the insertion layer 170.

The curved portion 123b can be divided into an inclined portion 1231 and an extending portion 1232.

The inclined portion 1231 refers to a portion inclined along an inclined surface L of the insertion layer 170 which will be described later. The extending portion 1232 refers to a portion extending from the inclined portion 1231 to the outside.

The inclined portion 1231 is formed parallel to the inclined surface L of the insertion layer 170, and the inclined angle of the inclined portion 1231 may be formed to be the same as the inclined angle of the inclined surface L of the insertion layer 170.

The insertion layer 170 is arranged along the surface formed by the diaphragm layer 150, the first electrode 121 and the etching stop portion 145. Therefore, the insertion layer 170 is partially disposed in the resonator 120 and is disposed between the first electrode 121 and the piezoelectric layer 123.

The insertion layer 170 is disposed around the central portion S to support the bent portion 123 b of the piezoelectric layer 123. Therefore, the bent portion 123b of the piezoelectric layer 123 can be divided into an inclined portion 1231 and an extended portion 1232 along the shape of the insertion layer 170.

The insertion layer 170 is arranged in an area other than the central portion S. For example, the insertion layer 170 may be disposed on the substrate 110 in the entire area except the central portion S or in some areas.

The insertion layer 170 is formed so that the thickness becomes larger as the side surface facing the central portion S moves away from the central portion S. Thus, the insertion layer 170 is formed by the inclined surface L having a constant inclination angle θ and the side surface facing the central portion S.

When the inclination angle θ of the side surface of the insertion layer 170 is formed to be less than 5°, in order to manufacture the insertion layer 170, the insertion layer 170 should be formed to be extremely thin or the area of the inclined surface L should be particularly large, so in fact Difficult to implement.

In addition, when the inclination angle θ of the side surface of the insertion layer 170 is greater than 70°, the inclination angle of the piezoelectric layer 123 or the second electrode 125 stacked on the insertion layer 170 is also formed to be greater than 70°. In this case, since the piezoelectric layer 123 or the second electrode 125 stacked on the inclined surface L is excessively bent, cracks may be generated in the bent portion.

Therefore, in the embodiment of the present invention, the inclination angle θ of the inclined surface L is formed in the range of 5° or more than 5° and 70° or less than 70°.

In the embodiment of the present invention, the inclined portion 1231 of the piezoelectric layer 123 is formed along the inclined surface L of the insertion layer 170 and is therefore formed to have the same inclination angle as the inclined surface L of the insertion layer 170. Therefore, the inclination angle of the inclined portion 1231 is also formed in the range of 5° or more and 70° or less than 70°, which is similar to the inclined surface L of the insertion layer 170. The configuration is also applicable to the second electrode 125 stacked on the inclined surface L of the insertion layer 170.

The insertion layer 170 may be formed of a dielectric material such as: silicon _{oxide (SiO 2} ), aluminum nitride (AlN), aluminum oxide (Al ₂ O ₃ ), silicon nitride (Si ₃ N ₄ ), magnesium oxide ( MgO), zirconium oxide (ZrO ₂ ), lead zirconium titanate (PZT) and gallium arsenide (GaAs), hafnium oxide (HfO ₂ ), titanium oxide (TiO ₂ ) and zinc oxide (ZnO), but can be derived from piezoelectric The material of layer 123 is formed.

In addition, the insertion layer 170 may be implemented by a metal material. When the volume acoustic resonator of the embodiment of the present invention is used for 5G communication, a large amount of heat is generated by the resonator, and therefore, the heat generated by the resonator 120 needs to be smoothly released. For this purpose, the insertion layer 170 of this embodiment may be made of an aluminum alloy material containing scandium (Sc).

The resonator 120 is configured to be spaced apart from the substrate 110 via a cavity C disposed under the diaphragm layer 150. Therefore, the diaphragm layer 150 is disposed under the first electrode 121 and the insertion layer 170 to support the resonator 120.

The cavity C is formed as a blank space, and can be formed by supplying etching gas (or etching solution) to the suction hole (the suction hole H in FIG. 1) during the process of manufacturing the acoustic resonator to remove a part of the sacrificial layer 140 .

The protective layer 127 is disposed along the surface of the acoustic resonator 100 to protect the acoustic resonator 100 from the outside. The protective layer 127 may be disposed along the surface formed by the second electrode 125 and the bent portion 123b of the piezoelectric layer 123.

The protective layer 127 may be formed to contain silicon nitride (Si ₃ N ₄ ), silicon _{oxide (SiO 2} ), magnesium oxide (MgO), zirconium oxide (ZrO ₂ ), aluminum nitride (AlN), lead silicate titanate (PZT) ), gallium arsenide (GaAs), hafnium oxide (HfO ₂ ), aluminum oxide (Al ₂ O ₃ ), titanium oxide (TiO ₂ ), and zinc oxide (ZnO) dielectric layer, but not limited to this.

The protective layer 127 may be formed as a single layer, but may be formed by stacking two layers with different materials as necessary. In addition, the protective layer 127 can be partially removed to adjust the frequency in the final manufacturing process. For example, the thickness of the protective layer 127 can be adjusted in the frequency micro-modulation process.

The first electrode 121 and the second electrode 125 may extend beyond the resonator 120. The first metal layer 180 and the second metal layer 190 may be respectively disposed on the upper surface of the extension portion.

The first metal layer 180 and the second metal layer 190 may be made of gold (Au), gold-tin (Au-Sn) alloy, copper (Cu), copper-tin (Cu-Sn) alloy, aluminum (Al), aluminum alloy or The combination is made. Here, the aluminum alloy may be an aluminum-germanium (Al-Ge) alloy or an aluminum-scandium (Al-Sc) alloy.

The first metal layer 180 and the second metal layer 190 can be used to electrically connect the first electrode 121 and the second electrode 125 of the acoustic resonator according to the embodiment of the present invention on the substrate 110 and electrically connect to other acoustic resonators arranged adjacent to each other. The connection wiring of the electrode, or as a terminal for external connection. However, it is not limited to this.

The first metal layer 180 may penetrate the protective layer 127 and be bonded to the first electrode 121.

In addition, in the resonator 120, the first electrode 121 is formed to have a larger area than the second electrode 125, and the first metal layer 180 is formed on the periphery of the first electrode 121.

Therefore, the first metal layer 180 is arranged along the periphery of the resonator 120 and is therefore arranged in a form surrounding the second electrode 125. However, it is not limited to this.

In the bulk acoustic resonator 100 according to the embodiment of the present invention configured as described above, as illustrated in FIGS. 4 to 6, the second inclined surface L2 is formed on the upper surface of the first electrode 121.

The second inclined surface L2 is formed to extend from the inclined surface of the aforementioned insertion layer 170 (hereinafter referred to as the first inclined surface L), and is formed to have an inclination angle θ2 smaller than the inclination angle θ of the first inclined surface L.

In the cross section of the resonator 120 cut to cross the central portion S, the insertion layers 170 may be respectively arranged in the extension portions E located on both sides of the central portion S. The second inclined surface L2 is arranged on both sides of the central portion S in a form extending from the first inclined surface L. Thus, the second inclined surface L2 may be formed along the entire first inclined surface L formed in the insertion layer 170.

Since the insertion layer 170 is arranged in the extension portion E along the boundary of the central portion S, the second inclined surface L2 is arranged in the central portion S along the boundary of the central portion S. In addition, the upper surface of the first electrode 121 extending from the lower end of the second inclined surface L2 is formed as a flat surface. Therefore, in the first electrode 121, the upper surface of the central portion S and the upper surface of the extension portion E are arranged on different planes. In addition, with regard to the second inclined surface L2, the thickness t1 of the first electrode 121 arranged in the central portion S (which is the lower end portion of the second inclined surface L2) is formed to be smaller than the thickness t1 arranged in the extension portion E (which is the second inclined surface). The thickness t2 of the first electrode 121 in the upper end portion of L2).

The second inclined surface L2 may be formed by etching a part of the upper surface of the first electrode 121 positioned in the central portion S. In this process, the insertion layer 170 can be used as a mask. Therefore, the second inclined surface L2 is formed in a form extending from the first inclined surface L.

When the second inclined surface L2 is provided in the first electrode 121 as described above, the reflective interface Q1 may be formed along the boundary between the flat surface of the first electrode 121 and the second inclined surface L2. Therefore, in addition to the sparse/dense/sparse/dense structure shown in FIG. 4, since an additional reflective interface Q1 is provided, it is possible to further suppress the leakage of energy in the resonator 120 to the outside of the resonator 120, thereby improving the body The effectiveness of acoustic resonators.

In addition, the bulk acoustic resonator according to the embodiment of the present invention may include a fourth inclined surface L4 formed in the diaphragm layer 150, as shown in FIG. 5.

The fourth inclined surface L4 is formed to extend from an inclined surface L3 (hereinafter referred to as a third inclined surface) formed at the end of the first electrode 121.

Similar to the second inclined surface L2, the fourth inclined surface L4 is formed to have an inclination angle θ4 smaller than the inclination angle θ3 of the third inclined surface L3.

Regarding the fourth inclined surface L4, the thickness t3 of the diaphragm layer 150 in the lower end portion of the fourth inclined surface L4 is formed to be smaller than the thickness t4 of the diaphragm layer 150 in the upper end portion of the fourth inclined surface L4.

The fourth inclined surface L4 may be formed in the diaphragm layer 150 along the entire third inclined surface L3 formed on the first electrode 121.

The fourth inclined surface L4 may be formed by partially etching the upper surface of the diaphragm layer 150. In this manufacturing process, the first electrode 121 can be used as a mask. Therefore, the fourth inclined surface L4 is formed to extend from the third inclined surface L3.

When the fourth inclined surface L4 is provided in the diaphragm layer 150 as described above, the reflective interface Q2 may be formed along the boundary of the fourth inclined surface L4. Therefore, since an additional reflective interface Q2 is provided, it is possible to further suppress the energy in the resonator 120 from leaking out of the resonator 120.

The present invention is not limited to the above-mentioned embodiment, and various modifications are possible.

Fig. 7 is a cross-sectional view schematically illustrating a bulk acoustic resonator according to another embodiment of the present invention.

Referring to FIG. 7, the configuration of the bulk acoustic wave resonator 200 described in the embodiment of the present invention is similar to that of the bulk acoustic wave resonator described in FIG. 3 and the shape of the insertion layer 170 disposed on the end side of the first electrode 121 The biggest difference. Therefore, a detailed description of the same components as those in the above-mentioned embodiment may be omitted, and the differences will mainly be further described.

As shown in FIG. 7, in the cross-section of the resonator 120 cut to cross the central portion S, the insertion layers 170 are respectively arranged in the extension portions E respectively located on both sides of the central portion S, where the first contact The right insertion layer 170 at the end of the electrode 121 is configured to only contact the third inclined surface L3, which is the inclined surface of the end of the first electrode 121 and does not cover the upper surface of the first electrode 121. For example, in the portion where the third inclined surface L3 is formed, the insertion layer 170 is formed to contact only the third inclined surface L3 and not the upper surface of the first electrode 121.

For this purpose, the insertion layer 170 of the embodiment of the present invention may be formed to be thicker than the first electrode 121.

As in the above embodiment, the first electrode 121 of the bulk acoustic wave resonator 200 of the embodiment of the present invention has a second inclined surface L2 extending from the first inclined surface L of the insertion layer 170 and a third inclined surface formed at the end L3, and the diaphragm layer 150 has a fourth inclined surface L4 extending from the third inclined surface L3. In addition, the second inclined surface L2 is formed to have an inclination angle smaller than that of the first inclined surface L, and the fourth inclined surface L4 is formed to have an inclination angle smaller than that of the third inclined surface L3.

In addition, the above-mentioned right insertion layer 170 is configured such that its end contacts the third inclined surface L3 of the first electrode 121 and the fourth inclined surface L4 of the diaphragm layer 150. Therefore, the right insertion layer 170 configured to contact the end of the first electrode 121 has three inclined surfaces having different inclination angles at the ends. As described above, the insertion layer 170 of the present invention can be modified in various forms.

Fig. 8 is a cross-sectional view schematically illustrating a volume acoustic resonator according to another embodiment of the present invention. Referring to FIG. 8, the bulk acoustic wave resonator 300 shown in the embodiment of the present invention includes the bulk acoustic wave resonator shown in FIG. 2 and the cover 50.

The cover 50 is provided to protect the resonator 120 from the external environment.

The cover 50 may be formed in the form of a cover plate having an internal space for accommodating the resonator 120. Therefore, the cover 50 is joined to the substrate 110 in such a way that the side wall 51 surrounds the periphery of the resonator 120.

The cover 50 may be bonded to the substrate 110 via a bonding member. Therefore, the lower surface of the side wall 51 serves as a bonding surface with the substrate 110.

The cover 50 can be formed by wafer-level wafer bonding. That is, the substrate wafer on which the plurality of unit substrates 110 are arranged and the cover wafer on which the plurality of cover covers 50 are arranged can be integrally formed by bonding with each other. Silicon (Si) can be used as the material of the cover, but it is not limited to this.

The substrate 110 of the embodiment of the present invention has a plurality of via holes 112 penetrating the substrate 110 on the lower surface thereof. In addition, the connecting conductor 113a and the connecting conductor 113b are formed inside each of the via holes 112.

The connecting conductor 113a and the connecting conductor 113b may be formed on the entire inner surface of the via hole 112, but are not limited thereto, or may be partially formed or formed in a form of completely filling the inner space of the via hole 112.

In addition, one end of the connecting conductor 113 a and the connecting conductor 113 b is connected to the external electrode 117 formed on the lower surface of the substrate 110, and the other end is connected to the first electrode 121 or the second electrode 125.

For example, the first connecting conductor 113a according to the embodiment of the present invention electrically connects the first electrode 121 and the external electrode 117, and the second connecting conductor 113b electrically connects the second electrode 125 and the other external electrode 117.

Therefore, the first connecting conductor 113a can penetrate the substrate 110 and the diaphragm layer 150 and is electrically connected to the first electrode 121, and the second connection conductor 113b can penetrate the substrate 110 and the diaphragm layer 150 and is electrically connected to the second electrode 125 . In this case, the second connection conductor 113b may be electrically connected to the second electrode 125 via the second metal layer 190.

In the embodiment of the present invention, only two via holes 112 and two connecting conductors 113a and 113b are illustrated and described, but the present invention is not limited to this, and if necessary, a larger number of via holes 112 and connecting conductors 113a and 113a can be provided. 113b.

Fig. 9 is a cross-sectional view schematically illustrating a bulk acoustic wave resonator according to another embodiment of the present invention.

Referring to FIG. 9, the configuration of the bulk acoustic wave resonator 400 described in the embodiment of the present invention is similar to the bulk acoustic wave resonator described in FIG. 8, except that the via hole 112 is configured with the connecting conductor 113a and the connecting conductor 113b. It is a difference that penetrates the cover 50 instead of the substrate 110.

Therefore, in the embodiment of the present invention, the via hole 112 and the connecting conductor 113a and the connecting conductor 113b are positioned above the first metal layer 180 and the second metal layer 190, and the connecting conductor 113a and the connecting conductor 113b are respectively connected to the via hole 112. The first metal layer 180 and the second metal layer 190.

Therefore, the connecting conductor 113a and the connecting conductor 113b are electrically connected to the first electrode 121 and the second electrode 125 via the first metal layer 180 and the second metal layer 190, respectively.

In this case, the upper surfaces (or bonding surfaces) of the first metal layer 180 and the second metal layer 190 can be arranged on the same plane, so that the cover 50 can be firmly bonded to the first metal layer 180 and the second metal layer 190.

In the bulk acoustic wave resonator 400 according to the embodiment of the present invention configured as described above, the external electrode 117 may be disposed on the upper surface of the outer surface of the cover 50 (see FIG. 9). In this case, the upper surface of the cover 50 can be used as a mounting surface.

As explained above, according to the present invention, since the bulk acoustic wave resonator provides an additional reflection interface through the inclined surface provided on the first electrode, it is possible to suppress the energy in the resonator from leaking out of the resonator as much as possible, thereby Improve the performance of the bulk acoustic resonator.

Although specific examples have been shown and described above, it will be obvious after understanding the present invention that forms and details can be made in these examples without departing from the scope of the patent application and the spirit and scope of its equivalents. Various changes. The examples described herein should be considered in a descriptive sense only and not for restrictive purposes. The description of the features or aspects in each example shall be regarded as applicable to similar features or aspects in other examples. If the described techniques are performed in a different order, and/or if they are combined in different ways and/or replaced or supplemented with other components or their equivalents, the appropriateness can be achieved. result. Therefore, the scope of the present invention is not defined by the detailed description, but by the scope of the patent application and its equivalents, and all changes within the scope of the patent application and its equivalents should be interpreted as being included in the present invention .

50: cover 51: side wall 100: bulk acoustic wave resonator/acoustic wave resonator/resonator 200, 300, 400: bulk acoustic wave resonator 110: substrate 112: via holes 113a, 113b: connecting conductor 115: insulating layer 117: exterior Electrode 120: resonator 121: first electrode 123: piezoelectric layer 123a: piezoelectric portion 123b: curved portion 1231: inclined portion 1232: extension portion 125: second electrode 125a: second electrode 127: protective layer 140: sacrificial layer 145: etching termination part 150: diaphragm layer 170: insertion layer 180: first metal layer 190: second metal layer A, B: part C: cavity E: extension part H: suction hole I-I', II- II', III-III': line L, L1, L2, L3, L4: inclined surface Q1, Q2: reflective interface S: central part t1, t2, t3, t4: thickness θ, θ ₁ , θ ₂ , θ ₃ , Θ ₄ : tilt angle

Fig. 1 is a plan view of an acoustic resonator according to an embodiment of the present invention. Fig. 2 is a cross-sectional view taken along line II' of Fig. 1. Fig. 3 is a cross-sectional view taken along the line II-II' of Fig. 1. Fig. 4 is a cross-sectional view taken along the line III-III' of Fig. 1. Fig. 5 is an enlarged view of part A of Fig. 2. Fig. 6 is an enlarged view of a part B of Fig. 4. FIG. 7 is a cross-sectional view schematically illustrating a bulk acoustic wave resonator according to another embodiment of the present invention. Fig. 8 is a cross-sectional view schematically illustrating a bulk acoustic wave resonator according to another embodiment of the present invention. Fig. 9 is a cross-sectional view schematically illustrating a bulk acoustic wave resonator according to another embodiment of the present invention. Throughout the drawings and detailed description, the same reference numbers refer to the same elements. The drawings may not be drawn to scale, and for clarity and convenience, the relative sizes, proportions, and descriptions of the elements in the drawings may be enlarged.

100: Bulk acoustic wave resonator/acoustic resonator/resonator

110: substrate

115: insulating layer

120: Resonator

121: first electrode

123: Piezo layer

123a: Piezoelectric part

123b: curved part

1231: Inclined part

1232: Extension

125: second electrode

127: Protective layer

140: Sacrifice Layer

145: Etching termination part

150: diaphragm layer

170: Insert layer

180: The first metal layer

190: second metal layer

A: Part

C: cavity

E: Extension

I-I': line

L: Inclined surface

S: central part

Claims (20)

A bulk acoustic wave resonator, which includes: A resonator including a central part in which a first electrode, a piezoelectric layer, and a second electrode are sequentially stacked on a substrate and an extension part arranged along the periphery of the central part; and An insertion layer disposed under the piezoelectric layer in the extension portion to raise the piezoelectric layer, Wherein the insertion layer includes a first inclined surface formed along a side surface facing the central portion, and the first electrode includes a second inclined surface extending from a lower end of the first inclined surface of the insertion layer . The bulk acoustic resonator of claim 1, wherein the second inclined surface includes a lower inclination angle than the first inclined surface. The bulk acoustic resonator of claim 1, wherein the first electrode includes a thickness of a lower end portion of the second inclined surface that is smaller than a thickness of an upper end portion of the second inclined surface. The bulk acoustic resonator of claim 1, wherein the second inclined surface is disposed in the central portion. The bulk acoustic resonator of claim 1, wherein the first electrode includes an upper surface in the central portion and an upper surface in the extension portion, and the upper surfaces are arranged on planes different from each other. Such as the bulk acoustic resonator of claim 1, which further includes: A diaphragm layer, which is disposed under the first electrode and the insertion layer to support the resonator; and A cavity that separates the resonator from the substrate. The bulk acoustic resonator of claim 1, wherein the third inclined surface is arranged along the end of the first electrode, and The diaphragm layer includes a fourth inclined surface extending from the lower end of the third inclined surface. The bulk acoustic resonator of claim 7, wherein the fourth inclined surface includes a lower inclination angle than the third inclined surface. The bulk acoustic resonator of claim 7, wherein the end of the insertion layer contacts the third inclined surface of the first electrode. The bulk acoustic resonator of claim 9, wherein the insertion layer is thicker than the first electrode. The bulk acoustic resonator of claim 1, which further includes a cover for accommodating the resonator therein and bonding to the substrate. Such as the bulk acoustic resonator of claim 11, which further includes: A plurality of via holes configured to penetrate the cover; and A plurality of connecting conductors are arranged in the plurality of via holes to electrically connect the first electrode and the second electrode to the outside. The bulk acoustic resonator of claim 12, which further includes external electrodes joined to the plurality of connecting conductors exposed on the outer surface of the cover. According to claim 12, the bulk acoustic wave resonator further includes a first metal layer and a second metal layer, the first metal layer and the second metal layer are disposed outside the resonator and are respectively joined to the first metal layer An electrode and the second electrode, The plurality of connecting conductors are electrically connected to the first electrode and the second electrode through the first metal layer and the second metal layer, respectively. The bulk acoustic resonator of claim 1, wherein the piezoelectric layer includes an inclined portion disposed on the first inclined surface, and The end of the second electrode is arranged on the inclined portion of the piezoelectric layer. A bulk acoustic wave resonator, which includes: A resonator including a central part in which a first electrode, a piezoelectric layer, and a second electrode are sequentially stacked on a substrate and an extension part arranged along the periphery of the central part; and An insertion layer disposed under the piezoelectric layer in the extension portion to raise the piezoelectric layer, The thickness of the first electrode in the central portion is smaller than the thickness in the extension portion. A bulk acoustic wave resonator, which includes: The central part includes a first electrode, a piezoelectric layer, and a second electrode stacked on the substrate in sequence; and An extension part disposed along the periphery of the central part, which includes the first electrode, the insertion layer, the piezoelectric layer, and the second electrode sequentially stacked on the substrate, Wherein the first electrode includes a first reflective interface in the central portion. The bulk acoustic resonator of claim 17, wherein the first reflection interface includes an inclined surface extending from the lower end surface of the insertion layer toward the center portion. The bulk acoustic resonator of claim 17, further comprising a diaphragm layer, the diaphragm layer being disposed under the first electrode to support the first electrode; and A cavity, which separates the first electrode from the substrate, Wherein the diaphragm layer includes a second reflective interface in the extension portion. The bulk acoustic resonator of claim 19, wherein the second reflection interface includes an inclined surface extending away from the central portion from the lower end of the first electrode.

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