A resonator, filter, communication device and method of manufacturing the same

Abstract

The present disclosure provides a bulk acoustic wave resonator, which comprises a substrate, the substrate having a first region therein or thereon; a first electrode layer, a functional material layer and a second electrode layer on the substrate; the first region, the first electrode layer, the functional material layer and the second electrode layer defining a second region and a third region; the second region having a tilted structure feature, an upper part of the tilted structure feature being projected closer to a central region of the second region than a lower part of the tilted structure feature. The present disclosure can better solve the harmful effect of the transverse mode on the performance of the resonator, can improve the spurious suppression capability, thereby improving the performance of the filter containing the resonator, and further improving the performance of the communication device containing the filter.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to a communication device and a manufacturing method thereof, and more particularly, to a communication device with a filter and a manufacturing method thereof. BACKGROUND

[0002] With the development of communication technology, filters for transmitting and / or receiving signals are included in portable and other types of communication devices. The filters can use various types of acoustic wave resonators according to different applications, such as a film bulk acoustic resonator (FBAR), a solidly mounted resonator (SMR), a coupled resonator filter (CRF), a bulk acoustic resonator (SBAR), a dual bulk acoustic resonator (DBAR), and the like.

[0003] In the prior art, a film bulk acoustic resonator (FBAR) is more suitable for portable communication devices, which is compatible with standard integrated manufacturing technology. As shown in Figure 1 A film bulk acoustic resonator (FBAR) generally has a structure including a piezoelectric material layer 30 sandwiched between two electrodes 10 and 20, and then the structure is placed in a case where an input electric signal is applied between the two plate electrodes, and the inverse piezoelectric effect causes the piezoelectric material layer to mechanically expand or contract due to the polarization of the piezoelectric material. As the input electric signal changes over time, the expansion and contraction of the piezoelectric material layer generates acoustic waves propagating in various directions and is converted into an electric signal through the piezoelectric effect.

[0004] The film bulk acoustic resonator (FBAR) of the above structure includes different lateral regions that can be affected by different types of resonance modes, including a first region where the upper and lower plate electrodes overlap the piezoelectric material and a second region at the edge of the upper and lower electrodes where the piezoelectric material does not overlap. The lateral mode generated by the energy scattering in the electrically excited mode. The lateral mode has a harmful effect on the performance of the film bulk acoustic resonator (FBAR).

[0005] In the prior art, to solve the above problem, the structure of the electrode is improved, for example, the upper electrode is designed with a frame to suppress or reduce the lateral mode. Figure 2 An improved structure of a film bulk acoustic resonator (FBAR) with a frame design of the upper electrode is shown in the figure. The frame has a protruding structure 40 and a recessed structure 50, however, the improved film bulk acoustic resonator (FBAR) has an OT edge that is not perpendicular due to the photolithography process during manufacturing, but has an angle as shown in Figure 3 The film bulk acoustic resonator (FBAR) has reduced spurious suppression capability.

[0006] The present disclosure is directed to the above technical problems, and designs a novel film bulk acoustic resonator (FBAR) structure, which can better solve the harmful effect of the transverse mode on the performance of the film bulk acoustic resonator (FBAR), and can improve the spurious suppression capability, improve the performance of the filter, and further improve the performance of the communication equipment. SUMMARY

[0007] Hereinafter, a brief summary of the present disclosure will be given in order to provide a basic understanding of some aspects of the present disclosure. It should be understood that this summary is not an exhaustive overview of the present disclosure. It is not intended to identify key or important parts of the present disclosure, nor is it intended to limit the scope of the present disclosure. Its purpose is only to give some concepts in a simplified form as a prelude to the more detailed description discussed later.

[0008] According to an aspect of the present disclosure, a bulk acoustic resonator is provided, which comprises: a substrate, the substrate having a first region therein or thereon; a first electrode layer, a functional material layer and a second electrode layer on the substrate; the first region, the first electrode layer, the functional material layer and the second electrode layer defining a second region and a third region; having a tilted structure feature in the second region, the upper part of the tilted structure feature in the second region being closer to the center region of the second region than the lower part of the tilted structure feature in the second region.

[0009] Further, the second electrode has a frame structure, and the frame structure has a first protrusion and a first recess.

[0010] Further, the tilted structure is a notch formed at the first protrusion of at least one frame of the second electrode frame structure and / or a notch formed on the functional material layer.

[0011] Further, the number of notches is set to 1-5.

[0012] Further, the included angle between the extension line of the two sidewalls of the notch and the horizontal plane is set to 10-80 degrees.

[0013] Further, the height of the notch is less than 100 nm, and the period is set to 50-100 nm.

[0014] Further, the notch formed at the first protrusion of the second electrode is asymmetrically arranged.

[0015] Further, the tilted structure is a second protrusion formed on at least one frame of the second electrode frame.

[0016] Further, the second protrusion is triangular or trapezoidal in shape.

[0017] Further, the second protrusion protrudes towards a central region of the second region.

[0018] Further, an angle of an inclined side of the second protrusion relative to a horizontal plane is 10-80 degrees.

[0019] Further, the second protrusion is symmetrically arranged on a frame of the second electrode.

[0020] According to another aspect of the present disclosure, a method for manufacturing a resonator is provided, comprising:

[0021] A substrate is provided; an acoustic reflecting structure is formed in or on the substrate; a first electrode layer is formed on the acoustic reflecting structure; a functional material layer is formed on the first electrode layer; a second electrode layer is formed on the functional material layer; the first region, the first electrode layer, the functional material layer and the second electrode layer define a second region and a third region; wherein an inclined structure feature is formed on the second electrode layer or the functional material layer of the second region, an upper part of the inclined structure feature projects closer to a central region of the second region than a lower part of the inclined structure feature.

[0022] Further, the inclined structure feature is formed by an inclined etching process or a nano-indentation process.

[0023] Further, the second electrode layer does not cover the inclined structure feature.

[0024] Further, the second electrode has a frame structure, and the frame structure has a first protrusion.

[0025] Further, the inclined structure is a notch formed on the first protrusion of at least one side frame of the frame structure of the second electrode and / or a notch formed on the functional material layer.

[0026] Further, the inclined structure further comprises a second protrusion formed on at least one side frame of the second electrode.

[0027] Further, an angle of an inclined side of the inclined structure relative to a horizontal plane is 10-80 degrees.

[0028] According to another aspect of the present disclosure, a filter is provided, comprising any one of the bulk acoustic wave resonators described above.

[0029] According to another aspect of the present disclosure, a communication device is provided, comprising any one of the filters described above.

[0030] Further, the communication device is a mobile phone, a personal digital assistant (PDA) or an electronic game device.

[0031] The scheme of the present disclosure can at least help to achieve one of the following effects: solving the harmful effect of transverse mode on the performance of a film bulk acoustic resonator (FBAR), improving the spurious suppression capability of a film bulk acoustic resonator (FBAR), and improving the performance of a filter containing a film bulk acoustic resonator (FBAR) and a communication device. BRIEF DESCRIPTION OF DRAWINGS

[0032] The specific content of the present disclosure will be described below with reference to the accompanying drawings, which will help to more easily understand the above and other purposes, features and advantages of the present disclosure. The accompanying drawings are only to illustrate the principles of the present disclosure. In the drawings, the sizes and relative positions of elements are not necessarily drawn according to scale.

[0033] Figures 1-3 A structural schematic diagram of a film bulk acoustic resonator (FBAR) in the prior art is shown;

[0034] Figures 4-5 A structural schematic diagram of a resonator according to a first embodiment and a process flow are shown;

[0035] Figures 6-7 A structural schematic diagram of a resonator according to a second embodiment and a process flow are shown;

[0036] Figures 8-10 A structural schematic diagram of a resonator according to a third embodiment and a process flow are shown. DETAILED DESCRIPTION

[0037] In the following, exemplary embodiments of the present disclosure will be described with reference to the accompanying drawings. In the specification, all features of implementing the present disclosure are not described for the sake of clarity and conciseness. However, it should be appreciated that in developing any such implementation of the present disclosure, many implementation-specific decisions would have to be made to achieve the developer's specific goals, and these decisions can vary from one implementation to another. It will be appreciated that such a development effort might be complex and time-consuming, but would nevertheless be a routine undertaking for those of ordinary skill in the art having the benefit of this disclosure.

[0038] It should also be noted that, in the drawings, only the device structures closely related to the scheme according to the present disclosure are shown, and other details not closely related to the present disclosure are omitted, in order to avoid obscuring the present disclosure due to unnecessary details.

[0039] It should be understood that the present disclosure is not limited to the described embodiments by virtue of the following description with reference to the drawings. In this context, features of the different embodiments can be transposed or used in combination with one another, and one or more features can be omitted in an embodiment.

[0040] First embodiment

[0041] See also Figures 4-5 A first embodiment of the acoustic wave resonator structure and method of the present disclosure is shown, wherein like reference numerals represent like parts.

[0042] A substrate is provided, in which an acoustic wave reflection region 1 consisting of a structure such as an air cavity or a Bragg reflection layer is formed. The substrate can be, for example, silicon (Si), gallium arsenide (GaAs), indium phosphide (InP), glass, sapphire, aluminum oxide, or the like. 、SiC The air cavity can be formed by etching; the Bragg reflector layer is formed by stacking thin films of different acoustic impedances. More preferably, the Bragg reflector layer is formed by stacking thin films of different acoustic impedances with a thickness controlled to be 1 / 4 wavelength.

[0043] A lower electrode layer 200 is formed on the substrate to completely cover the acoustic wave reflection area. The lower electrode layer can be a single layer or multiple layers. A piezoelectric layer 300 is formed on the lower electrode layer, and an upper electrode layer 400 is provided on the piezoelectric layer. The upper electrode layer can be a single layer or multiple layers. The upper / lower electrodes can be formed of one or more conductive materials, such as various metals compatible with semiconductor processes including tungsten (W), molybdenum (Mo), iridium (Ir), aluminum (Al), platinum (Pt), ruthenium (Ru), niobium (Nb) or hafnium (Hf). The materials of the upper electrode and the lower electrode can be the same or different. The piezoelectric layer 300 can be formed of any piezoelectric material compatible with semiconductor processes, such as aluminum nitride (AlN), doped aluminum nitride or zirconate titanate (PZT). The overlapping area between the upper electrode layer, the piezoelectric layer and the lower electrode layer above any of the acoustic wave reflection areas 1 is defined as the active area 2 of the acoustic wave resonator, and the other areas outside the active area are defined as the peripheral area 3 of the acoustic wave resonator. The active area 2 has a regional center C.

[0044] On the upper electrode is formed a Figure 4As shown in the frame structure, the frame structure has a protruding feature 401 and a recessed feature 402, and an angled inclined structure feature 403 is formed at the protruding feature 401 of at least one of the frame structures of the upper electrode, more specifically, the inclined structure feature is a notch formed at the protruding feature of at least one of the frame structures. The projection of the notch falls within the active area, and the projection of the upper opening of the notch on the substrate is closer to the center area of the active area than the projection of the bottom surface of the notch on the substrate. The included angle between the extension lines of the two side walls of the notch and the horizontal plane can be set to 10-80 degrees, and the height of the notch can be set in the range of less than 100 nm. It can be further understood that the number of notch parts can also be multiple, and when the notch is multiple, it can be set at equal intervals, and the interval is 50-400 nm. Of course, the notches can also be set at unequal intervals. More preferably, the number of notch parts can be set to 1-5. It can be further understood that the frame can form notch parts with symmetrical or asymmetrical number and structure at each frame, and the notch parts can be symmetrical or asymmetrical relative to the center of the active area, or symmetrical or asymmetrical at a single frame. By setting the notch part in the frame structure of the upper electrode, it is beneficial to reflect the transverse wave, and the adverse effects such as energy attenuation between the active area and the peripheral area caused by the transverse mode are reduced or lowered.

[0045] Based on the device structure of the first embodiment of the present disclosure, as Figure 5 The manufacturing method thereof is further described below.

[0046] Step one: provide a substrate, the selection of the substrate material is as described above, which will not be repeated here. The substrate mainly plays the role of a support carrier. For example, a Si substrate has good mechanical robustness, which can ensure that it is firm and reliable during processing and packaging.

[0047] Step two: etch the substrate to form an air cavity, fill the air cavity with a different acoustic impedance thin film stack of, for example, 1 / 4 wavelength thickness, or fill the air cavity with a sacrificial layer, which is used to support the deposition of the upper thin film. It should also be understood that a support layer can also be formed on the substrate, and a groove is formed in the support layer by etching, and the sacrificial layer is filled in the groove. The sacrificial layer can be selected from phosphosilicate glass, silicon dioxide, amorphous silicon, and other thin film materials that can be compatible with the deposition temperature of the subsequent thin film, do not contaminate the process system, have good etching selectivity and chemical polishing properties.

[0048] Step three: then, the lower electrode layer is formed on the substrate, it should be understood that the material of the lower electrode is not limited to the electrode material as described above, the electrode material with high acoustic impedance and high acoustic speed can be used. It should also be understood that a support layer structure can also be formed on the substrate first, a groove is formed by etching the support layer, the lower electrode material is deposited in the groove, and the lower electrode layer is formed by removing the lower electrode material outside the active area. The support layer can be selected from silicon nitride, silicon carbide, or AIN, etc.

[0049] Step four: a piezoelectric layer is deposited on the lower electrode layer, the material of the piezoelectric layer can be selected from materials that meet the bandwidth requirements of wireless mobile communication transceiving signals. As described above, the material compatible with the semiconductor process is preferred, such as aluminum nitride (AIN) or titanate zirconate (PZT).

[0050] Step five: an upper electrode material layer is deposited on the piezoelectric layer, and a frame structure is formed on the upper electrode by etching process, the frame structure has a protruding structure at the outer edge of the upper electrode and a recessed structure. It can be understood that the frame structure can also include air bridges or air wings, etc. It can be further understood that the protruding structure can be integrally formed with the upper electrode, or it can be an additional protruding frame structure. When the protruding structure is an additional protruding frame structure, it can be selected from the same or different metal materials as the upper electrode material, or the protruding structure can be a dielectric material such as silicon dioxide or aluminum oxide, etc. It can be further understood that the frame structure is not limited to being located within the active area, and the frame structure can partially extend out of the active area.

[0051] Step six: the formation process of the inclined notch part in the upper electrode frame can be realized by an inclined etching process. The specific process of the inclined etching is as follows: a hard mask layer is deposited on the substrate including the upper electrode, the hard mask layer is lithographed to transfer the pattern of the inclined notch to the hard mask layer, then the inclined notch is formed in the frame part of the upper electrode by adjusting the etching angle of the ion beam through the etching process. Finally, the hard mask layer is removed. Step six can be replaced by providing a template with an inclined notch nano-pattern, the template material uses quartz that can be penetrated by ultraviolet light, ultraviolet curing glue is injected on the template to transfer the three-dimensional pattern with inclined notches to the ultraviolet curing glue, and then the ultraviolet curing glue is fixed on the substrate including the upper electrode material layer through nano-indentation technology, and the upper electrode layer including the inclined notch is formed by etching process.

[0052] Second embodiment

[0053] Figure 6A second embodiment of the present disclosure illustrating a structure and method of a sound wave resonator is shown, wherein the same reference numerals represent the same components.

[0054] The second embodiment differs from the first embodiment mainly in that a tilted structural feature is formed on the upper surface of the piezoelectric layer 300, more specifically, the tilted structural feature is a tilted notch 403. The projection of the notch 403 falls within or outside the active region, and the upper opening of the notch 403 is closer to the center region C of the active region 2 than the bottom surface of the notch 403. The angle between the extension line of the two sidewalls of the notch and the horizontal plane can be set to a range of 10-80 degrees, the height of the notch 403 can be set to a range of less than 100 nm, and the period can be set to a range of 50-400 nm. The notch 403 and the lower surface of the upper electrode 400 do not overlap each other. It can be further understood that the number of notches 403 can also be multiple. When there are multiple notches, they can be arranged at equal intervals, and the interval can be 50-400 nm. Of course, the notches can also be arranged at unequal intervals. More preferably, the number of notches 403 can be set to 1-5. It can be further understood that the notches 403 on the piezoelectric layer 300 can form notches 403 of a number, structure, symmetry or asymmetry with respect to the center region of the active region 2, and the notches can also be symmetrically or asymmetrically arranged at a single frame. By arranging the notches in the piezoelectric layer 300, the transverse wave is reflected, and the adverse effects such as discontinuity of electric field or exponential energy decay between the active region and the peripheral region due to transverse mode are avoided or reduced.

[0055] Further alternatively, the tilted notch 403 can be formed in the upper electrode 400 and the piezoelectric layer 300 at the same time, and the notch 403 can also be symmetrically or asymmetrically arranged as described above.

[0056] Based on the device structure with the tilted notch 403 in the piezoelectric layer in the second embodiment of the present disclosure, the main difference between the manufacturing method and the manufacturing method in the first embodiment is as follows Figure 7 as shown:

[0057] Before step five: The forming process of the tilted notch in the piezoelectric layer can also be realized by a tilted etching process. The specific process of the tilted etching is as follows: a hard mask layer is deposited on the piezoelectric layer, the hard mask layer is photoetched to transfer the pattern of the tilted notch to the hard mask layer, then the tilted etching is performed by adjusting the etching angle of the ion beam through the etching process to form the tilted notch in the frame part of the upper electrode. Finally, the hard mask layer is removed.

[0058] Alternatively, a template with a tilted notch nano-pattern is prepared, the template material uses quartz which can be penetrated by ultraviolet light, ultraviolet curing glue is injected on the template, the three-dimensional pattern with tilted notches is transferred to the ultraviolet curing glue, the ultraviolet curing glue is fixed on the piezoelectric layer through nano-indentation technology, and the tilted notch part is transferred to the piezoelectric layer through an etching process.

[0059] Third embodiment

[0060] Figure 8 A third embodiment of structures and methods of the present disclosure including acoustic wave resonators is shown, in which like reference numerals refer to like parts throughout.

[0061] The third embodiment differs from the foregoing embodiments mainly in that in the present embodiment, a frame structure and a recess structure are formed on the upper electrode, an angled tilted structure feature is formed at at least one of the side frames in the frame structure of the upper electrode, and more specifically, the tilted structure feature is a wedge-shaped protrusion 404 formed at the side frame of the frame. The protruding direction of the wedge-shaped protrusion extends toward the center of the active region, and the wedge angle of the wedge-shaped protrusion can be in the range of less than 10-80 degrees. Further, the wedge-shaped protrusions are symmetrically arranged at the side frames of the frame.

[0062] It can be understood that, as Figure 9 shown, the wedge-shaped protrusion 404 of the upper electrode can cooperate with the tilted notch part 403 of the upper electrode to facilitate reflection of the transverse wave, weaken or reduce the adverse effects such as energy attenuation between the active region and the peripheral region caused by the transverse mode, and improve the spurious wave suppression capability of the film bulk acoustic resonator (FBAR).

[0063] Further, the wedge-shaped protrusion 404 of the upper electrode can cooperate with the tilted notch part in the piezoelectric layer to facilitate reflection of the transverse wave, weaken or reduce the adverse effects such as energy attenuation between the active region and the peripheral region caused by the transverse mode, and improve the spurious wave suppression capability of the film bulk acoustic resonator (FBAR).

[0064] It can be understood that the wedge-shaped protrusion and the notch part can be arranged in a symmetric or asymmetric arrangement mode.

[0065] Based on the device structure with the wedge-shaped protrusion in the upper electrode in the third embodiment of the present disclosure, the manufacturing method is as shown in Figure 10 the difference between the manufacturing method in the first embodiment mainly lies in that:

[0066] Step six: the forming process of the wedge-shaped protrusions in the upper electrode frame can also be realized by a process of oblique etching. The specific process of oblique etching is as follows: a hard mask layer is deposited on the substrate including the upper electrode, the hard mask layer is photoetched, a nano-pattern with oblique gaps is transferred to the hard mask layer, then the oblique gaps are formed in the frame part of the upper electrode by adjusting the etching angle of the ion beam through an etching process for oblique etching, and finally the hard mask layer is removed.

[0067] Alternatively, a template with a wedge-shaped protrusion nano-pattern is provided in step six, the template material uses quartz which can be penetrated by ultraviolet light, ultraviolet curing glue is injected on the template, a three-dimensional pattern of the upper electrode including wedge-shaped protrusions is transferred to the ultraviolet curing glue, the ultraviolet curing glue is fixed on the substrate including the upper electrode material through nano-indentation technology, and the pattern of the upper electrode is formed through an etching process.

[0068] Fourth embodiment

[0069] A filter can be used in the field of portable communication devices such as mobile phones, personal digital assistants (PDAs), electronic game devices, etc., and the filter can include any of the acoustic wave resonators in the above embodiments.

[0070] The present disclosure is described above in connection with specific embodiments, but those skilled in the art will clearly understand that these descriptions are exemplary and not limiting to the scope of protection of the present disclosure. Those skilled in the art can make various modifications and changes to the present disclosure according to the spirit and principles of the present disclosure, and these modifications and changes are also within the scope of the present disclosure.

Claims

1. A bulk acoustic wave resonator, comprising: a substrate having an acoustic wave reflecting region therein or thereon; a lower electrode layer, a functional material layer and an upper electrode layer on the substrate, the upper electrode layer having a frame structure; an overlapping region between the lower electrode layer, the functional material layer and the upper electrode layer above the acoustic wave reflecting region defining an active region, and a region outside the active region defining a peripheral region; a tilted structure feature at at least one side frame of the frame structure of the upper electrode layer of the active region and / or in an upper surface of the functional material layer, an upper part of the tilted structure feature being projected closer to a central region of the active region than a lower part of the tilted structure feature. 2.The resonator of claim 1, wherein the frame structure of the upper electrode layer has a first protrusion and a first recess. 3.The resonator of claim 2, the tilted structure being a notch formed at the first protrusion of at least one side frame of the frame structure of the upper electrode layer and / or a notch formed on the functional material layer. 4.The resonator of claim 3, the number of the notch being set to 1-5. 5.The resonator of claim 3, an included angle between an extension line of two sidewalls of the notch and a horizontal plane being set to 10-80 degrees. 6.The resonator of claim 5, a height of the notch being less than 100 nm, and a period being set to 50-100 nm. 7.The resonator of any one of claims 4-6, the notch formed at the first protrusion of the upper electrode layer being set in an asymmetric manner. 8.The resonator of claim 2, the tilted structure being a second protrusion formed on at least one side frame of the frame of the upper electrode layer. 9.The resonator of claim 8, the second protrusion being in a shape of a triangle or a trapezoid. 10.The resonator of claim 8, the second protrusion being protruded towards the central region of the active region. 11.The resonator of claim 8 or 9, an inclined angle of an inclined side of the second protrusion relative to a horizontal plane being 10-80 degrees. 12.The resonator of claim 10, the second protrusion being symmetrically set on the frame of the upper electrode layer. 13.A method for manufacturing a resonator, comprising: providing a substrate; forming an acoustic reflecting region in or on the substrate; forming a lower electrode layer on the acoustic reflecting region; forming a functional material layer on the lower electrode layer; forming an upper electrode layer on the functional material layer, the upper electrode layer having a frame structure; and an overlapping region between the lower electrode layer, the functional material layer and the upper electrode layer above the acoustic reflecting region defining an active region, and a region outside the active region defining a peripheral region. wherein a tilted structure feature is formed at at least one frame of the upper electrode layer of the active region and / or on the upper surface of the functional material layer, an upper part of the tilted structure feature is closer to a center region of the active region than a lower part of the tilted structure feature.

14. The method of claim 13, wherein the tilted structure feature is formed by a tilted etching process or a nano-indentation process.

15. The method of claim 13, wherein the upper electrode layer does not cover the tilted structure feature.

16. The method of claim 13, wherein the frame structure of the upper electrode layer has a first protrusion.

17. The method of claim 16, wherein the tilted structure is a notch formed at the first protrusion of at least one frame of the frame structure of the upper electrode layer and / or a notch formed on the functional material layer.

18. The method of claim 16, wherein the tilted structure further comprises a second protrusion formed at at least one frame of the frame structure of the upper electrode layer.

19. The method of claim 13, wherein an angle of a tilted side of the tilted structure feature with respect to a horizontal plane is 10-80 degrees.

20. A filter comprising the bulk acoustic wave resonator of any one of claims 1-19.

21. A communication device comprising the filter of any one of claims 1-20.

22. The communication device of claim 21, wherein the communication device is a cell phone, a personal digital assistant (PDA), or an electronic game device.

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