Suspended frame bulk acoustic wave devices

Abstract

To provide a bulk acoustic wave (SAW) device having a high quality factor (Q).SOLUTION: A raised frame bulk acoustic wave device 101 includes: a piezoelectric layer 116 arranged between a first electrode 114 and a second electrode 118; and a suspended frame structure suspended over a gap 122. The gap 122 exists between the first electrode 114 and the piezoelectric layer 116, or between the second electrode 118 and the piezoelectric layer 116, and is disposed between a portion of the first electrode 114 and a portion of the second electrode 118 that extend past an end of the piezoelectric layer 116. A conductive material penetrates through an opening of a passivation layer 124 at a location directly above the gap 122. A raised frame region 134 includes: a first raised frame portion 160; a second raised frame portion 162 disposed outward of the first raised frame portion 160, and a suspended frame portion 136 disposed outward of the second raised frame portion 162.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] Cross-reference of priority application This application claims the interests of U.S. Provisional Patent Application No. 63 / 251,316, filed on 1 October 2021, entitled “Suspension Frame Bulk Acoustic Wave Device,” and further claims the interests of U.S. Provisional Patent Application No. 63 / 251,259, filed on 1 October 2021, entitled “Bulk Acoustic Wave Device with Performance Improvement Gap,” the contents of each of these applications incorporated herein by reference in their entirety.

[0002] Some embodiments disclosed herein relate to acoustic wave devices such as bulk acoustic wave devices, and more particularly to filters including bulk acoustic wave devices. [Background technology]

[0003] Elastic wave filters can be implemented in radio frequency electronic systems. For example, the filter in the radio frequency front end of a mobile phone may include one or more elastic wave filters. Multiple elastic wave filters can be arranged as a multiplexer. For example, two elastic wave filters can be arranged as a duplexer.

[0004] An elastic wave filter may include multiple resonators arranged to filter radio frequency signals. Examples of elastic wave filters include surface acoustic wave (SAW) filters and bulk elastic wave (BAW) filters. A BAW filter may include a BAW resonator. In a BAW resonator, elastic waves propagate within the bulk of the piezoelectric layer. Examples of BAW resonators include thin-film bulk elastic wave resonators (FBARs) and solid-mount resonators (SMRs).

[0005] Despite the existence of various BAW devices, improvements to BAW devices and filters are still needed. [Overview of the project]

[0006] Each innovation described in the claims has several aspects, and no single one is solely responsible for its desirable attributes. Without limiting the scope of the claims, some notable features of this disclosure are briefly described below.

[0007] According to one aspect of this disclosure, a bulk acoustic wave device may include a first electrode, a second electrode, and a piezoelectric layer between the first and second electrodes. The device may have an effective region in which the piezoelectric layer overlaps the first and second electrodes. This effective region may include an intermediate area. The device may have a raised frame structure outside the intermediate area of ​​the effective region. The raised frame structure includes a gap between the first and second electrodes, and at least a portion of the raised frame structure is a suspension frame suspended over the gap.

[0008] The piezoelectric layer may be located on the first electrode, the second electrode on the piezoelectric layer, and a gap may exist between the first electrode and the piezoelectric layer. The piezoelectric layer may be located on the first electrode, the second electrode on the piezoelectric layer, and a gap may exist between the second electrode and the piezoelectric layer. The raised frame structure includes an internal raised frame section outside the intermediate area and inside the suspension frame. The suspension frame may have a height greater than the height of the internal raised frame section. The raised frame structure may include a raised frame layer extending over at least a portion of the gap. The raised frame layer may extend inward into the gap and form at least a portion of the internal raised frame section of the raised frame structure. The raised frame layer may have an acoustic impedance lower than at least one of the first electrode, the second electrode, and the piezoelectric layer. The bulk acoustic wave device further includes a passivation layer on the first electrode, the second electrode, the piezoelectric layer, and the raised frame structure. A recessed frame region may exist between the raised frame structure and the intermediate area, and the passivation layer may be thinner in the recessed frame region than in the intermediate area. The bulk acoustic wave device includes a conductive layer positioned on a portion of the passivation layer, the portion of which extends into an opening in the passivation layer to electrically contact the second electrode. The opening in the passivation layer may be located directly above the gap. A portion of the gap may extend laterally outward beyond one end of the piezoelectric layer. A portion of the gap may extend downward beyond the underside of the piezoelectric layer. A portion of the first electrode may extend laterally beyond one end of the piezoelectric layer, and a portion of the second electrode may extend laterally beyond that end of the piezoelectric layer, and the gap may be located between the portion of the first electrode and the portion of the second electrode. The distance between the portion of the first electrode and the portion of the second electrode may be less than the thickness of the piezoelectric layer.

[0009] According to one aspect of the present disclosure, a bulk acoustic wave device may include a first electrode, a second electrode, a piezoelectric layer between the first electrode and the second electrode, and a raised frame structure, the raised frame structure including a suspension frame portion above the gap between the first electrode and the second electrode, and an internal raised frame portion laterally inward of the suspension frame portion.

[0010] The raised frame structure may include a raised frame layer between the first electrode and the second electrode. The internal raised frame portion may include a first portion of the raised frame layer that is not located above the gap, and the suspension frame portion may include a second portion of the raised frame layer that extends above the gap. The raised frame layer may have an acoustic impedance lower than at least one of the first electrode, the second electrode, and the piezoelectric layer. The bulk elastic wave device further includes a passivation layer on the first electrode, the second electrode, the piezoelectric layer, and the raised frame structure. The bulk elastic wave device further includes a conductive layer located on a portion of the passivation layer. A portion of the conductive layer extends into an opening in the passivation layer and electrically contacts the second electrode. The opening in the passivation layer may be located directly above the gap. A portion of the gap may extend laterally outward beyond one end of the piezoelectric layer. A portion of the first electrode may extend laterally beyond one end of the piezoelectric layer, and a portion of the second electrode may extend laterally beyond one end of the piezoelectric layer, with a gap between the portion of the first electrode and the portion of the second electrode. The distance between the portion of the first electrode and the portion of the second electrode may be less than the thickness of the piezoelectric layer. The bulk acoustic wave device may further include a reflector cavity, and the first electrode may be located between the reflector cavity and the piezoelectric layer. The bulk acoustic wave device may include an acoustic Bragg reflector, and the first electrode may be located between the acoustic Bragg reflector and the piezoelectric layer.

[0011] In one aspect of this disclosure, a filter comprising one or more bulk acoustic wave devices is disclosed herein. The filter may be at least one of a band-pass filter, a band-stop filter, a ladder filter, and a lattice filter. The filter comprising one or more bulk acoustic wave devices disclosed herein may form part of at least one of a diplexer, a duplexer, a multiplexer, and a switching multiplexer. A radio frequency module may include an acoustic wave die comprising at least one filter comprising one or more bulk acoustic wave devices from among the bulk acoustic wave devices disclosed herein, and radio frequency circuit elements coupled to the acoustic wave die. The acoustic wave die and radio frequency circuit elements may be enclosed in a common module package. A wireless communication device may include an acoustic wave filter comprising one or more bulk acoustic wave devices from among the bulk acoustic wave devices disclosed herein, an antenna operably coupled to the acoustic wave filter, a radio frequency amplifier operably coupled to the acoustic wave filter and configured to amplify radio frequency signals, and a transceiver communicating with the radio frequency amplifier. The wireless communication device may include a baseband processor communicating with the transceiver. The elastic wave filter may be included in the radio frequency front-end. The wireless communication device may be a user device.

[0012] According to one aspect of the present disclosure, a bulk acoustic wave device may include a first electrode, a second electrode, a piezoelectric layer between the first electrode and the second electrode, wherein a portion of the first electrode extends laterally beyond one end of the piezoelectric layer, and a portion of the second electrode extends laterally beyond that end of the piezoelectric layer, and a gap disposed between the portion of the first electrode and the portion of the second electrode.

[0013] The bulk acoustic wave device may include a suspension frame structure that includes a portion of the gap. The bulk acoustic wave device may include a raised frame structure, which includes a suspension frame portion suspended over a portion of the gap and an internal raised frame portion that is laterally inward of the suspension frame portion. The raised frame structure may include a raised frame layer between the first electrode and the second electrode. The internal raised frame portion may include a first portion of the raised frame layer that is not located over the gap, and the suspension frame portion may include a second portion of the raised frame layer that extends over the gap. The raised frame layer may have an acoustic impedance lower than at least one of the first electrode, the second electrode, and the piezoelectric layer. The suspension frame portion may have a greater height than the internal raised frame portion. The distance between a portion of the first electrode that extends laterally beyond one end of the piezoelectric layer and a portion of the second electrode that extends laterally beyond that end of the piezoelectric layer may be less than the thickness of the piezoelectric layer. A first portion of the gap may extend over a portion of the top of the piezoelectric layer, a second portion of the gap may extend along the lateral end of the piezoelectric layer, and a third portion of the gap may extend below the bottom of the piezoelectric layer. The first portion of the gap may be located between the piezoelectric layer and the second electrode, and the second portion of the gap may extend laterally beyond one end of the piezoelectric layer. The second electrode may include a first portion extending along the top surface of the piezoelectric layer, a second portion extending away from the first electrode, and a third portion extending beyond the top surface of the piezoelectric layer toward the first electrode. The bulk acoustic wave device may include a passivation layer on the first electrode, the second electrode, and the piezoelectric layer. The bulk acoustic wave device may include a conductive layer positioned on a portion of the passivation layer. A portion of the conductive layer extends into an opening in the passivation layer and electrically contacts the second electrode. The opening in the passivation layer may be located directly above the gap.

[0014] According to one aspect of the present disclosure, a bulk acoustic wave device may include a first electrode, a second electrode, a piezoelectric layer between the first and second electrodes, a gap between the first and second electrodes, a passivation layer, and a conductive layer, wherein the second electrode is located between the piezoelectric layer and the passivation layer, the passivation layer is located between a first portion of the conductive layer and the second electrode, and the second portion of the conductive layer extends into an opening in the passivation layer and is in electrical contact with the second electrode. The opening in the passivation layer may be located directly above the gap between the first and second electrodes.

[0015] An opening in the passivation layer may be located directly above the first electrode, the piezoelectric layer, and the second electrode. The bulk acoustic wave device may include an effective region in which the piezoelectric layer overlaps the first and second electrodes. One end of the upper electrode may define the first end of the effective region, and one end of the piezoelectric layer may define the second end of the effective region opposite to the first end. The bulk acoustic wave device may include a suspension frame structure that includes a portion of the gap. The bulk acoustic wave device may include a raised frame structure, which includes a suspension frame portion suspended over a portion of the gap, and an internal raised frame portion that is laterally inward of the suspension frame portion. The raised frame structure may include a raised frame layer between the first and second electrodes, the internal raised frame portion may include a first portion of the raised frame layer that is not located over the gap, and the suspension frame portion may include a second portion of the raised frame layer that extends over the gap. The raised frame layer may have an acoustic impedance lower than at least one of the first electrode, the second electrode, and the piezoelectric layer. The suspension frame portion may have a greater height than the internal raised frame portion. A portion of the first electrode may extend laterally beyond one end of the piezoelectric layer, and a portion of the second electrode may extend laterally beyond the same end of the piezoelectric layer, and a gap may be located between the portion of the first electrode and the portion of the second electrode. The distance between the portion of the first electrode extending laterally beyond one end of the piezoelectric layer and the portion of the second electrode extending laterally beyond the same end of the piezoelectric layer may be less than the thickness of the piezoelectric layer. A first portion of the gap may extend above a portion of the top of the piezoelectric layer, a second portion of the gap may extend along the lateral end of the piezoelectric layer, and a third portion of the gap may extend below the bottom of the piezoelectric layer. A first portion of the gap may be located between the piezoelectric layer and the second electrode, and a second portion of the gap may extend laterally beyond one end of the piezoelectric layer. The second electrode may include a first portion extending along the upper surface of the piezoelectric layer, a second portion extending away from the first electrode, and a third portion extending beyond the upper surface of the piezoelectric layer toward the first electrode. The bulk acoustic wave device may include a reflector cavity, and the first electrode may be located between the reflector cavity and the piezoelectric layer.The bulk acoustic wave device may include an acoustic Bragg reflector, and the first electrode may be located between the acoustic Bragg reflector and the piezoelectric layer.

[0016] A filter may include one or more of the bulk acoustic wave devices disclosed herein. The filter may be at least one of a band-pass filter, a band-stop filter, a ladder filter, and a lattice filter. A filter including one or more of the bulk acoustic wave devices disclosed herein may form part of at least one of a diplexer, a duplexer, a multiplexer, and a switching multiplexer. A radio frequency module may include an acoustic wave die having at least one filter having one or more bulk acoustic wave devices from among the bulk acoustic wave devices disclosed herein, and radio frequency circuit elements coupled to the acoustic wave die. The acoustic wave die and radio frequency circuit elements may be enclosed in a common module package. A wireless communication device may include an acoustic wave filter including one or more bulk acoustic wave devices from among the bulk acoustic wave devices disclosed herein, an antenna operably coupled to the acoustic wave filter, a radio frequency amplifier operably coupled to the acoustic wave filter and configured to amplify radio frequency signals, and a transceiver communicating with the radio frequency amplifier. The wireless communication device may include a baseband processor communicating with the transceiver. The elastic wave filter may be included in the radio frequency front-end. The wireless communication device may be a user device.

[0017] According to one aspect of the present disclosure, a method for fabricating a bulk acoustic wave device includes forming a first electrode on a substrate, forming a piezoelectric layer on the first electrode, forming a sacrificial layer on the piezoelectric layer, forming a second electrode on the sacrificial layer, and removing the sacrificial layer to create a gap between the first electrode and the second electrode, the gap being used to suspend a portion of the second electrode.

[0018] The method may include forming an internal raised frame portion positioned laterally inward of the suspension frame. The suspension frame may be formed to have a height greater than the height of the internal raised frame. The method may include forming a raised frame layer in which a first portion lies above the piezoelectric layer but does not extend above the sacrificial layer, and a second portion extends above the sacrificial layer. The method may include forming a first raised frame layer above the piezoelectric layer, and the second electrode is formed above the first raised frame layer. The method may include forming a second raised frame layer above the second electrode. The first raised frame layer may have a lower acoustic impedance than the second raised frame layer. The method may include forming a passivation layer above the second electrode. The method may include forming an opening through the passivation layer and forming a conductive layer above a portion of the passivation layer, the portion of which extends into the opening in the passivation layer and electrically contacts the second electrode. The opening through the passivation layer may be positioned directly above the gap. A portion of the sacrificial layer may be formed to extend laterally outward beyond one end of the piezoelectric layer, and removal of the sacrificial layer may create a gap extending laterally outward beyond that end of the piezoelectric layer. The method may include forming a cavity sacrificial layer on a portion of a substrate, and forming a first electrode on the cavity sacrificial layer, and the method may include removing the cavity sacrificial layer to create a cavity between the substrate and the first electrode. The cavity sacrificial layer may be removed to form a cavity at the same time that the sacrificial layer is removed to form a gap.

[0019] According to one aspect of the present disclosure, a method for making a bulk acoustic wave device may include forming a first electrode on a substrate; forming a piezoelectric layer on the first electrode, wherein a portion of the first electrode extends beyond one end of the piezoelectric layer; forming a sacrificial layer on the portion of the piezoelectric layer and on the portion of the lower electrode; forming a second electrode on the sacrificial layer, wherein a portion of the second electrode extends beyond the one end of the piezoelectric layer; and removing the sacrificial layer to create a gap between the portion of the first electrode and the portion of the second electrode.

[0020] The gap may float a portion of the second electrode to provide a suspension frame. The method may include forming an internal raised frame portion disposed laterally inward of the suspension frame. The suspension frame may be formed to have a height greater than that of the internal raised frame. The method may include forming a raised frame layer where a first portion is present on the piezoelectric layer but does not extend over the sacrificial layer and a second portion extends over the sacrificial layer. The method may include forming a first raised frame layer on the piezoelectric layer, the second electrode is formed on the first raised frame layer, and the method may include forming a second raised frame layer on the second electrode. The first raised frame layer may have a lower acoustic impedance than the second raised frame layer. The method may include forming a passivation layer on the second electrode. The method may include forming an opening through the passivation layer and forming a conductive layer on a portion of the passivation layer, a portion of the conductive layer extending into the opening of the passivation layer to make electrical contact with the second electrode. The opening through the passivation layer may be disposed directly above the gap. The method may include forming a cavity sacrificial layer on a portion of the substrate. The first electrode may be formed on the cavity sacrificial layer. The method may include removing the cavity sacrificial layer to provide a cavity between the substrate and the first electrode. The cavity sacrificial layer may be removed to form the gap and simultaneously removed to form the cavity.

Brief Description of the Drawings

[0021] Embodiments of the present disclosure are described below through non-limiting examples with reference to the accompanying drawings, and the same reference numerals may refer to similar features throughout.

[0022] [Figure 1] FIG. 1 is a plan view of a bulk acoustic wave device according to an embodiment. [Figure 2] FIG. 2 is a cross-sectional view of a suspension frame bulk acoustic wave device according to an embodiment. [Figure 3]It is a cross-sectional view of a suspension frame bulk acoustic wave device of another embodiment. [Figure 3A] It is a cross-sectional view of a suspension frame bulk acoustic wave device of another embodiment. [Figure 3B] It is a cross-sectional view of a suspension frame bulk acoustic wave device of another embodiment. [Figure 4] It is a cross-sectional view of a ridge frame bulk acoustic wave device of one embodiment. [Figure 4A] It is a cross-sectional view of a ridge frame bulk acoustic wave device of another embodiment. [Figure 5] It is a graph showing experimental data for comparing the quality factor (Q) values of a plurality of BAW devices. [Figure 6] It is a graph showing experimental data for comparing spurious modes or noise of a plurality of BAW devices. [Figure 7] It is a graph showing experimental data for comparing a plurality of BAW devices having different electromechanical coupling coefficient (kt 2) values. [Figure 8] It is a cross-sectional view of a suspension frame bulk acoustic wave device of another embodiment. [Figure 9] It is a cross-sectional view of a suspension frame bulk acoustic wave device of another embodiment. [Figure 9A] It is a cross-sectional view of a suspension frame bulk acoustic wave device of another embodiment. [Figure 9B] It is a cross-sectional view of a suspension frame bulk acoustic wave device of another embodiment. [Figure 10] It is a cross-sectional view of a suspension frame bulk acoustic wave device of another embodiment. [Figure 11] It is a cross-sectional view of a suspension frame bulk acoustic wave device of another embodiment. [Figure 12] It is a cross-sectional view of a suspension frame bulk acoustic wave device of another embodiment. [Figure 12A] It is a cross-sectional view of a suspension frame bulk acoustic wave device of another embodiment. [Figure 12B] It is a plan view of a bulk elastic device of one embodiment. [Figure 12C] It is a cross-sectional view of an example of a BAW device. [Figure 13] This is a schematic diagram of an example of an elastic wave ladder filter. [Figure 14] This is a schematic diagram of one example of Duplexa. [Figure 15] This is a schematic diagram of an example multiplexer. [Figure 16] This is a schematic block diagram of a module that includes one antenna switch and multiple duplexers, each containing one or more raised-frame bulk elastic wave devices. [Figure 17A] This is a schematic block diagram of a module comprising one power amplifier, one radio frequency switch, and multiple duplexers, each including one or more raised frame bulk acoustic wave devices. [Figure 17B] This is a schematic block diagram of a module that includes one low-noise amplifier, one radio frequency switch, and multiple elastic wave filters, including one or more raised-frame bulk elastic wave devices. [Figure 18] This is a schematic block diagram of a module that includes one power amplifier, one radio frequency switch, and one duplexer including one or more raised frame bulk acoustic wave devices. [Figure 19A] This is a schematic block diagram of a wireless communication device that includes multiple filters, each containing one or more raised-frame bulk acoustic wave devices. [Figure 19B] This is a schematic block diagram of another wireless communication device that includes multiple filters, including one or more raised-frame bulk acoustic wave devices. [Modes for carrying out the invention]

[0023] The following detailed description of a given embodiment presents various descriptions of a particular embodiment. However, the innovation described herein can be embodied in numerous different forms defined and covered, for example, by the claims. In this specification, the same reference numeral refers to drawings showing identical or functionally similar elements. It should be understood that the elements shown in the drawings are not necessarily to scale. It should also be understood that a given embodiment may include more elements than shown in the drawings, and / or subsets of the elements shown in the drawings. Furthermore, some embodiments may also include any suitable combination of features from two or more drawings.

[0024] The positions and directions described herein may be given in relation to the orientation shown in the drawings, so the illustrated devices may be positioned in different orientations during use. For example, in some examples, the substrate is shown as being at the bottom of the device, but the substrate may still be considered at the bottom of the device even when installed in an inverted configuration.

[0025] A high quality factor (Q) is generally desirable for developing high-performance bulk acoustic wave (BAW) filters. Bulk acoustic wave (BAW) devices may include a raised frame structure and / or a suspension frame structure. The raised frame structure and / or suspension frame structure can reduce lateral energy leakage from the main acoustically effective region of the bulk acoustic wave device. In some implementation examples, a BAW device may include a single-layer raised frame structure. In some implementation examples, a BAW device may include a multi-layer raised frame structure. A BAW device may include a raised frame structure having a layer containing a material such as silicon dioxide with a relatively low acoustic impedance (e.g., lower than one or both of the electrodes and / or piezoelectric layers). A BAW device may include a gap (e.g., filled with air) beneath the raised frame structure so that at least a portion of the raised frame structure becomes a suspension frame. The suspension frame structure of a BAW device can facilitate achieving a relatively high Q (in some cases, for regions above the resonant frequency and / or anti-resonant frequency). BAW devices having the raised frame structure and / or suspension frame structure disclosed herein can, in some cases, achieve low insertion loss and / or low gamma loss. BAW devices having the raised frame structure and / or suspension frame structure disclosed herein can, in some cases, achieve a relatively high electromechanical coupling coefficient (k) which is desirable for a given application such as a relatively wide passband filter. t 2 ) can be achieved.

[0026] To achieve a high Q, a raised frame, which may also be called a boundary ring, can block lateral energy leakage from the effective domain of a BAW resonator to the passive domain of the BAW resonator. While a raised frame can improve Q, it cannot capture all leakage energy. In some examples, a raised frame can generate relatively large TE spurious modes, which may also be called raised frame modes, that are below the primary resonant frequency of the BAW resonator. This can cause gamma degradation in the carrier aggregation band for the filter. Gamma may be called the reflection coefficient. In some examples, a wide raised frame can be used to give a high Q value. However, a wide raised frame also reduces the electromechanical coupling coefficient (k t 2 A wide raised frame can degrade the TE and / or result in large TE spurious modes and / or transverse spurious modes. A recessed frame placed between the raised frame and the effective area can suppress transverse spurious modes with resonant frequencies higher than those of the effective area in the case of a type 2 vibration resonator such as an AIN-based piezoelectric layer. A wide raised frame can also increase gamma degradation.

[0027] Some aspects of this disclosure relate to bulk acoustic wave resonators including a suspension frame structure that can improve Q below the resonant frequency, for example, as described herein. The suspension frame structure also provides a higher k compared to other BAW devices lacking the suspension frame structure. t 2This can provide a low value, low amount of spurious noise, low insertion loss, and / or low gamma loss. The suspension frame structure may be located outside the effective region of the bulk acoustic wave resonator or along the periphery of the effective region. In some embodiments, the suspension frame may be located outside the unsuspended raised frame structure. The raised frame and / or suspension frame may contain materials with relatively low acoustic impedance. For example, the low acoustic impedance material may be placed between the top electrode of the bulk acoustic wave resonator and the piezoelectric layer. For example, the gap between the piezoelectric layer and the material with low acoustic impedance may, in some embodiments, form the suspension frame structure.

[0028] In some implementations, low gamma loss can be achieved by ensuring that the raised frame spurious modes are outside the carrier aggregation band. Some embodiments disclosed herein may include a raised frame portion, which may include a low acoustic impedance material capable of generating spurious modes at lower frequencies than other types of BAW devices. In some cases, the BAW device may be configured such that the raised frame modes for spurious modes are outside the carrier aggregation band, so as not to give gamma loss or to give low gamma loss. For example, in a carrier aggregation application, a multiplexer may include a common node arranged to receive a carrier aggregation signal, a first filter having a passband associated with a first carrier of the carrier aggregation signal, and a second filter coupled to the first filter at the common node, having a second passband associated with a second carrier of the carrier aggregation signal. The first filter may include a BAW resonator comprising a raised frame structure made of a material having low acoustic impedance that can increase the gamma of the first filter in the passband of the second filter, as disclosed herein. Furthermore, some of the BAW devices disclosed herein may include a suspension frame (in addition to, for example, the raised frame), the suspension frame may be configured to suppress spurious modes. That is, in some embodiments, both the raised frame and the suspension frame may contribute to low gamma loss and improved performance of the BAW device.

[0029] Furthermore, some of the raised frame structures disclosed herein may have low acoustic impedance materials configured such that the difference between the effective acoustic impedance of the raised frame domain and the effective acoustic impedance of the effective domain can provide a high Q. In some embodiments, the raised frame structure may provide high-energy mode reflections in the lateral direction, reducing mode conversion from the dominant mode to other lateral modes around the anti-resonant frequency. Thus, the configuration of low acoustic impedance layers or materials in the raised frame structure can significantly increase the Q compared to, for example, other BAW devices or other raised frame structures. In some embodiments, gaps in the suspension frame can at least partially separate or insulate one or more structures from the piezoelectric layer, reducing the transmission of vibrations between them. This increases the Q value and / or other performance parameters of the BAW device as described herein.

[0030] Although some embodiments disclosed herein are described with reference to a single raised frame structure having, for example, a single layer of low acoustic impedance material, various suitable principles and advantages described herein can be applied to multilayer raised frame structures having two, three or more raised frame layers. For example, in some cases, the first raised frame layer may contain a relatively low acoustic impedance material, while the second raised frame layer may contain a relatively high acoustic impedance material. The second raised frame layer may contain a material that is heavier or denser than the material of the first raised frame layer. In some cases, the second raised frame layer may be made of the same material as the electrodes of the bulk acoustic wave resonator. The suspension frame may include gaps beneath, for example, the first and second raised frame layers.

[0031] Figure 1 is a plan view of a raised frame bulk acoustic wave device 100. As shown in Figure 1, the bulk acoustic wave device 100 may include a frame zone 102 around the periphery of the effective area of ​​the bulk acoustic wave device 100. The frame zone 102 may be referred to as a boundary ring in a given example. Suspension frame structures and / or raised frame structures may be present in the frame zone 102. The raised frame structures and / or suspension frame structures may be implemented according to any suitable principles and advantages disclosed herein. The frame zone 102 may be located outside the intermediate area 104 of the effective area of ​​the bulk acoustic wave device 100. One or more raised frame layers and / or gaps may be present in the frame zone 102 and extend above the metal electrodes. Figure 1 shows that the metal electrodes are in the intermediate area 104 and the raised frame layers are in the frame zone 102. One or more other layers may be included above the metal electrodes and the raised frame layers. For example, silicon dioxide may be included on top of the metal electrodes and the raised frame layer. Figure 1 also shows that the piezoelectric layer 106 of the bulk acoustic wave device 100 may be located below the metal electrodes and the raised frame layer.

[0032] Several embodiments of the raised frame bulk acoustic wave device are described with reference to a cross-sectional example along the line A to A' in Figure 1. Any suitable combination of the features of the bulk acoustic wave devices disclosed herein can be combined with one another. Any of the bulk acoustic wave devices disclosed herein may be, for example, bulk acoustic wave resonators in filters arranged to filter radio frequency signals.

[0033] Figure 2 is a schematic cross-sectional view of an example of a bulk acoustic wave (BAW) device 100 having a raised frame structure. The BAW device 100 may include a support substrate 110, a cavity 112 (e.g., a reflector cavity), a first electrode or lower electrode 114 disposed on the support substrate 110, a piezoelectric layer 116 disposed on the lower electrode 114, a second electrode or upper electrode 118 disposed on the piezoelectric layer 116, a raised frame structure or raised frame layer 120 disposed at least partially between the piezoelectric layer 116 and the upper electrode 118, and a passivation layer 124 disposed on the upper electrode 118.

[0034] The support substrate 110 may be a silicon substrate, but other suitable substrates may be mounted as alternatives to the silicon substrate. One or more layers, such as a passivation layer, may be placed between the lower electrode 114 and the support substrate 110. In some embodiments, the cavity 112 may be an air cavity.

[0035] The piezoelectric layer 116 may be positioned between the first electrode 114 and the second electrode 118. The piezoelectric layer 116 may be an aluminum nitride (AlN) layer or any other suitable piezoelectric layer. The effective region 130 or effective domain of the BAW device 100 may be defined above an elastic reflector, such as a cavity 112, by the portion of the piezoelectric layer 116 that overlaps with both the lower electrode 114 and the upper electrode 118. The lower electrode 114 and / or the upper electrode 118 may have relatively high acoustic impedance. For example, the lower electrode 114 and / or the upper electrode 118 may include molybdenum (Mo), tungsten (W), ruthenium (Ru), iridium (Ir), platinum (Pt), an alloy containing Ir and Pt, or any suitable alloy and / or combination of any of these materials. However, other suitable conductive materials may also be used. The upper electrode 118 may be formed from the same material as the lower electrode 114 in a given example. However, in some cases, different materials may be used for the lower electrode 114 and the upper electrode 118.

[0036] The BAW device 100 shown may include an effective region 130 having a primary acoustically active region 132 and a raised frame region 134, the raised frame region 134 at least partially or completely surrounding the primary acoustically active region 132 (for example, in a plan view). In the cross-sectional view of Figure 2, the raised frame region 134 may be present on opposite sides of the primary acoustically active region 132. The primary acoustically active region 132 may be referred to as the central region or intermediate area of ​​the effective region 130. The primary acoustically active region 132 may set the primary resonant frequency of the BAW device 100. With respect to the primary acoustically active region 132, there may be a significant (e.g., exponential) drop in acoustic energy in the piezoelectric layer 116 in the frame region 134 when in the primary mode. A recessed frame region 140 may be positioned between the primary acoustically active region 132 and the raised frame region 134.

[0037] The raised frame layer 120 may be positioned between the first electrode or lower electrode 114 and the second electrode or upper electrode 118. As shown in Figure 2, the raised frame layer 120 may be positioned between the piezoelectric layer 116 and the second electrode 118. The raised frame layer 120 may extend beyond the effective region 130 of the bulk acoustic wave device 100, as shown in Figure 2, which may be advantageous in certain examples for manufacturability reasons.

[0038] The raised frame layer 120 may be made of a low acoustic impedance material. The low acoustic impedance material may have a lower acoustic impedance than the material of the first electrode 114. The low acoustic impedance material may have a lower acoustic impedance than the material of the second electrode 118. The low acoustic impedance material may have a lower acoustic impedance than the material of the piezoelectric layer 116. As an example, the first raised frame layer 120 may be silicon dioxide (SiO2). Other oxide materials may also be used, and the raised frame structure or raised frame layer 120 may be an oxide raised frame structure or an oxide raised frame layer. The raised frame layer 120 may be a silicon nitride (SiN) layer, a silicon carbide (SiC) layer, or any other suitable low acoustic impedance layer. The raised frame layer 120 may have a relatively low density. The density and / or acoustic impedance of the first raised frame layer 120 may be lower than that of the lower electrode 114, the upper electrode 118, and / or the piezoelectric layer 116 of the BAW device 100.

[0039] The BAW device 100 may have a gap 122 (e.g., a cavity or recess) beneath at least a portion of the raised frame structure. The gap 122 may be formed between the raised frame layer 120 and the piezoelectric layer 116. The gap 122 may contain any suitable material, but in some embodiments it may be filled with air. The gap 122 may be an air gap or air cavity. The gap 122 may be a cavity. The gap 122 may be formed using a sacrificial layer, for example, polysilicon or any suitable material which is removed during the manufacturing process to leave the gap 122. The gap 122 may lift the upper layer. The gap lifts one or more layers to define at least partially the raised frame structure 134.

[0040] The raised frame structure 134 may have a suspension frame section 136 and an internal raised frame section 138. The suspension frame section 136 may be positioned above the gap 122. The gap 122 may levitate one or more of the raised frame layer 120, the upper electrode 118, and / or the passivation layer 124. In some configurations, the internal raised frame section 138 is not positioned above the gap 122. The internal raised frame section 138 may be positioned inward of the suspension frame section 136 (for example, so as to approach the main acoustically effective area 132) and / or inward of the gap 122. The suspension frame section 136 may be higher than the internal raised frame section 138. For example, the suspension frame section 136 may extend further than the internal raised frame section 138 in a direction perpendicular to the piezoelectric layer 116. The internal raised frame portion 138 can be raised by the thickness of the raised frame layer 120. The suspension frame portion 136 can be raised by the thickness of the gap 122 plus the thickness of the raised frame layer 120. The gap 122 can increase the height of the BAW device 100 in the raised frame region 134. Therefore, the height of the BAW device 100 in the suspension frame region 136 can be greater than that of other parts of the effective region 130, for example, the intermediate area of ​​the effective domain.

[0041] The internal raised frame portion 138 may have a sloped region 137 and a non-sloped region 139. The non-sloped portion 139 of the internal raised frame portion 138 may be substantially parallel to the piezoelectric layer 116 (for example, with respect to its upper surface). The raised frame layer 120 may have a substantially uniform thickness in the non-sloped portion 139. The raised frame layer 120 may be inclined downward and / or tapered in the sloped portion 137. The upper surface of the sloped portion 137 of the internal raised frame portion 138 (or the raised frame layer 120) may form an angle 150 with respect to the upper surface of the non-sloped portion 139 of the internal raised frame portion 138 (or the raised frame layer 120). The thickness of the first raised frame layer 120 may decrease as it moves along the direction from the raised frame structure toward the main acoustically effective region 132 (or intermediate area).

[0042] The suspension frame portion 136 may have a sloped region 133 and a non-sloped region 135. The non-sloped portion 135 of the suspension frame portion 136 may be substantially parallel to the piezoelectric layer 116 (for example, with respect to its upper surface). The raised frame layer 120 may have a substantially uniform thickness in the non-sloped portion 135. The raised frame layer 120 may have a substantially uniform thickness in the sloped portion 137 of the suspension frame 136. The tapering of the gap 122 may give a slope to the sloped portion 133. The thickness of the gap 122 may taper or narrow along the inward direction. The upper surface of the sloped portion 133 of the suspension frame portion 136 (or the lower side of the raised frame layer 120) may form an angle 150 with respect to the upper surface of the non-sloped portion 135 of the suspension frame portion 136 (or the raised frame layer 120). The suspension frame section 136 may decrease in thickness or height as it moves along the direction from the raised frame structure toward the main acoustically effective area 132 (or intermediate area).

[0043] In some embodiments, the gap 122 is open on a first side (e.g., the right side in Figure 2) and closed on a second side (e.g., the left side in Figure 2). The gap 122 may have an internal tapering side with tapering thickness (e.g., corresponding to a sloped portion 133), and the gap 122 may have an external tapering side with tapering thickness (e.g., located outside the effective area 130). The raised frame layer 120 may abut the piezoelectric layer 116 in an internal area (e.g., associated with an internal raised frame portion 138). When moving radially outward, the raised frame layer 120 may tilt away from the piezoelectric layer 116 (e.g., in a sloped portion 133) and may generally extend parallel to the piezoelectric layer 116 (e.g., in a non-sloped portion 135). The raised frame layer 120 may tilt toward the piezoelectric layer 116 (for example, in the radially outer region of the effective area 130) and then come into contact with the piezoelectric layer 116. That is, the gap 122 may be sealed between, for example, the raised frame layer 120 and the piezoelectric layer 116. Many variations are possible. For example, the gap 122 may be closed on both sides (for example, as on the left side of Figure 2). Alternatively, the gap 122 may be open on both sides (for example, as on the right side of Figure 2).

[0044] The gap 122 may extend circumferentially around the BAW device 100, for example, along the periphery of the effective region 130 or along the periphery of the raised frame region. The gap 122 may be a single continuous cavity extending around the BAW device 100 (for example, only 360 degrees), or the gap 122 may have multiple sub-parts or cavities separated from each other by, for example, a wall or structural support. In some cases, a cross section passing through the BAW device 100 (for example, along the line from A to A' in Figure 1) may have a first gap portion (for example, the gap 122 portion on the left side of Figure 2) and a second gap portion (for example, the gap 122 portion on the right side of Figure 2). The main acoustically effective region 132 may be located between the first gap portion and the second gap portion. The first and second gap portions may have substantially symmetrical cross-sectional areas and / or shapes with respect to at least several portions of the first and second gap portions within the effective region 130. In some cases, a portion of the first or second gap portion that lies outside the effective region 130 (e.g., outward-facing of the lower electrode 114, outward-facing of the piezoelectric layer 116, and / or outward-facing of the upper electrode 118) may be asymmetrical with respect to the other corresponding portion of the second or first gap portion. For example, referring to Figure 2, the inward-tapering portions of the first and second gap portions (e.g., corresponding to the gradient portion 133) may be substantially symmetrical. A portion or all of the non-gradient portion or uniform-thickness portion (e.g., corresponding to the non-gradient region 135) may be substantially symmetrical with respect to the first and second gap portions. In the example of Figure 2, the left gap portion has an outward-tapering portion, while the right gap portion does not. For example, the outward-facing side of the right gap portion may be open. The symmetry of the gap can be beneficial to the performance of BAW devices.

[0045] Many variations are possible. In some embodiments, both gap portions may be closed. For example, the gap portion on the right side of Figure 2 may be closed and may be similar to or symmetrical to the gap portion on the left side of Figure 2. In some embodiments, the gap portions may be open. For example, the gap portion on the left side of Figure 2 may be closed and may be similar to or symmetrical to the gap portion on the right side of Figure 2.

[0046] The passivation layer 124 may be placed on the upper electrode 118 and / or on the raised frame layer 120 and / or on the gap 122. Any suitable passivation material can be used for the passivation layer 124, but it may be a silicon dioxide layer. The passivation layer 124 may be formed to have different thicknesses in different regions of the BAW device 100. For example, as shown in Figure 2, the passivation layer 124 may be thinner in the recessed frame region 140 than in the main acoustically effective region 132 or in other parts such as the raised frame region 134. In some cases, the recessed frame region 140 may contribute to achieving a relatively high Q, for example, below the resonant frequency. For example, the combination of the recessed frame region 140 and the raised frame structure of the BAW device 100 may contribute to achieving a relatively high Q, for example, below the resonant frequency. In some embodiments, the recessed frame region 140 can be omitted, for example, by using a passivation layer 124 having a substantially uniform thickness. In some embodiments, the passivation layer 124 can also be omitted.

[0047] The sloping portion of the raised frame structure may have an angle of 150 with respect to the horizontal. An angle of 150 is the angle with respect to the lower layer (e.g., the piezoelectric layer). The sloping portion of the raised frame layer 120 or the layer lying above it may have an upper surface inclined by an angle of 150 (e.g., downward or toward the piezoelectric layer 116 or the lower electrode 114). The sloping angle 150 of the raised frame layer 120 may affect the layer above the raised frame layer 120. The gap 122 may also have a sloping portion having a sloping angle of 150. This, too, may affect the layer lying above it. The sloping portion 133 of the suspension frame section 136 may have a sloping angle of 150. The sloping portion 137 of the internal raised frame section 138 may have a sloping angle 150 that is the same as or different from the sloping angle of the suspension frame 136. The upper electrode 118 and / or passivation layer 124 may also have a sloping angle of 150. The gradient angle 150 may be less than 90° or less than about 40° in some embodiments. In some cases, the tapering angle may be about 5°, about 10°, about 15°, about 20°, about 30°, about 45°, about 60°, about 75°, or any value in between, or any range in between. For example, in some examples, the angle 150 may be in the range of about 10° to about 30° with respect to the gradient portion of the raised frame and / or suspension frame in the gradient region, or to other related layers. In some embodiments, the gradient angle 150 may vary along the length of the related gradient portion. For example, the gradient portion may start with a small angle and transition to a larger angle. In some cases, the gradient portion may have curvature.

[0048] Figure 3 shows a cross-sectional view of a BAW device 101 which may be similar to the BAW device 100 in Figure 2, except as described herein. Figure 3A shows a cross-sectional view of a BAW device 101 which may be similar to the BAW device 100 in Figure 2 or the BAW device 101 in Figure 3, except as described herein. Figure 3A shows a cross-sectional view of a BAW device 101 which may be similar to the BAW device 100 in Figure 2 or the BAW device 101 in Figure 3, except as described herein. The BAW device 101 may include a support substrate 110, a cavity 112 (e.g., a reflector cavity), a first electrode or lower electrode 114 disposed on the support substrate 110, a piezoelectric layer 116 disposed on the lower electrode 114, a second electrode or upper electrode 118 disposed on the piezoelectric layer 116, a raised frame structure or raised frame layer 120 at least partially disposed between the piezoelectric layer 116 and the upper electrode 120, a gap 122 (e.g., a cavity) between the piezoelectric layer 116 and the raised frame layer 120, and a passivation layer 124 disposed on the upper electrode 118.

[0049] The BAW device 101 may have an effective region 130 or an effective domain. The effective region 130 or effective domain may be defined by the portion of the piezoelectric layer 116 that overlaps with both the lower electrode 114 and the upper electrode 118. The main acoustic effective region 132 may be located in the central or intermediate area of ​​the effective region 130. The recessed frame region 140 may be positioned outward from the main acoustic effective region 132. The raised frame region 134 or raised frame structure may be positioned outward from the recessed frame region 140.

[0050] The raised frame region 134 may include a first raised frame portion 160, a second raised frame portion 162 which may be positioned outward from the first raised frame portion 160, and a suspension frame portion 136 which may be positioned outward from the second raised frame portion 162. The first raised frame portion 160 may have a first height, and the second raised frame portion 162 may have a second height greater than the first height. The raised frame layer 120 may abut the piezoelectric layer 116 along a first area, and the raised frame layer 120 may have steps along a second area to form a gap 122 between the raised frame layer 120 and the piezoelectric layer 116. The second area may be positioned outward from the first area. In some embodiments, the height of the first raised frame portion 160 may be substantially the same as the thickness of the raised frame layer 120 (for example, in at least the first area abutting the piezoelectric layer 116). The first raised frame portion 160 may be provided by at least an upper electrode 118 having a stepped portion and being lifted by the raised frame layer 120 (for example, a first area of ​​the raised frame layer 120).

[0051] In some embodiments, the height of the second raised frame portion 162 may be substantially the same as the combined thickness of the gap 122 and the raised frame layer 120 (for example, in at least a second area above the gap 122). The height difference between the second raised frame portion 162 and the first raised frame portion 160 may be substantially the same as the thickness of the gap 122. The second raised frame portion 162 may be provided by at least an upper electrode 118 having a stepped portion and being lifted by the raised frame layer 120 (for example, its second area) and the gap 122.

[0052] In some embodiments, the suspension frame section 136 may have the same height as the second raised frame section 162. The suspension frame section 136 may be the portion of the raised frame structure directly above the gap 122. The second raised frame section 162 may be the portion of the raised frame structure that is raised above the first raised frame section 160 (for example, by the gap 122) but is not directly above the gap 122, due to, for example, the thickness of the material in the sloping or inclined step portion of the layer. In some embodiments, the suspension frame section 136 may be considered as the portion of the second raised frame section 162 that is positioned above the gap 122. In some configurations, the entire second raised frame section 162 may be positioned above the gap 122, so that the second raised frame section 162 also becomes the suspension frame section 136 (for example, as in the configuration of Figure 2).

[0053] In some embodiments, the raised frame region 134 may include a suspension frame portion 136 corresponding to the portion of the raised frame structure directly above the gap 122 or suspended above the gap 122. The suspension frame portion may correspond to a second area of ​​the raised frame layer 120. This second area is separated from the piezoelectric layer 116 by the gap 122. The second raised frame portion 162 may correspond to a first area of ​​the raised frame layer 120. This first area is in contact with the piezoelectric layer 116 or is not above the gap 122. The first raised frame portion 160 may correspond to an area of ​​the upper electrode 118 that is lifted by the raised frame layer 120. In some embodiments, a portion of the lifted upper electrode 118 may be positioned inward from the first raised frame layer 120, for example, due to the thickness of the material in a sloped portion or inclined step portion.

[0054] In some embodiments, the piezoelectric layer 116 may have a stepped portion (which may be defined, for example, by having a stepped portion such that the piezoelectric layer 116 is positioned above the lower electrode 114). The gap 122 may include a stepped portion corresponding to the stepped portion in the piezoelectric layer 116. At least a portion of the upper part of the gap 122 is positioned above the lower electrode 114, and at least a portion of the lower part of the gap 122 is not positioned above the lower electrode 114. The lower part of the gap may extend outward beyond one end of the lower electrode 114. As shown on the left side of Figure 3, this stepped portion may be located between the upper and lower portions of the gap 122. In some embodiments, the stepped portion in the gap 122 may be omitted (for example, as shown in Figure 2). In some embodiments, the suspension frame 136 may be larger on one side (for example, the left side in Figure 3) than on the other side (for example, the right side in Figure 3). In some embodiments, the upper electrode 118 may extend above the stepped portion in the gap 122. In some embodiments, the effective area 130 may extend over the stepped portion in the gap 122. In some configurations, the gap portion (for example, the portion of the gap portion that overlaps with the effective area 130) may be asymmetrical (as shown, for example, in Figure 3) or substantially symmetrical as described herein.

[0055] In some embodiments, a portion of the gap 122 may be open (for example, as shown on the right side of Figure 3). The passivation layer 124 may extend across one or both ends of the upper electrode 118 and may meet a raised frame layer 120 located below the upper electrode 118. In some embodiments, the raised frame layer 120 and the passivation layer 124 may be made from the same material (e.g., silicon dioxide or other oxide material). The raised frame layer 120 and / or the passivation layer 124 may extend downward to the piezoelectric layer 116 (or other lower layer) at one point facing outward from the gap 122 and capable of closing at least a portion of the gap 122 (for example, as shown on the left side of Figure 3).

[0056] In some embodiments, the first conductive layer 166 may be located on at least a portion of the passivation layer 124. The passivation layer 124 may have an opening that allows for an electrical connection between the first conductive layer 166 and the upper electrode 118. The first conductive layer 166 extends into or through the opening to contact the upper electrode 118. The opening or electrical contact between the first conductive layer 166 and the upper electrode 118 may be located directly above the gap 122, but other locations may also be used. The conductive layer 166 may contact the upper electrode 118, penetrate the opening in the passivation layer 124, and / or extend outward from the opening (e.g., above the passivation layer 124). Electrical signals and / or power can be delivered to and from the upper electrode 118 via the first conductive layer. The opening or electrical contact between the first conductive layer 166 and the upper electrode 118 may be located directly above the lower electrode 114, the piezoelectric layer 116, the upper electrode 118, a portion of the gap 122, and / or a portion of the raised frame layer 120. In some embodiments, the effective region 130 may omit the area covered by the first conductive layer 166, as shown in Figures 3A and 3B, even if that area includes the overlap of the piezoelectric layer 116, the lower electrode 114, and the upper electrode 118.

[0057] In some embodiments, the second conductive layer 168 may be positioned on a portion of the lower electrode 114. For example, a portion of the lower electrode 114 may extend outward beyond one end of the piezoelectric layer 116 (for example, on the right side of Figure 3). The second conductive layer 168 may be positioned on this portion of the lower electrode 114 (for example, in direct contact). The second conductive layer 168 can supply electrical signals and / or power to and from the lower electrode 168. In some embodiments, either or both of the first conductive layer 166 and the second conductive layer 168 may be omitted. For example, in some implementation examples, electrical signals can be directly delivered to or from either or both of the electrodes 114 and 118.

[0058] The first conductive layer 166 and / or the second conductive layer 168 can be made from a material having a higher conductivity than the upper electrode 118 or the lower electrode 114. For example, the first conductive layer 166 and / or the second conductive layer 168 can be made from gold or another conductive metal (e.g., copper or aluminum). In some embodiments, the material of the upper electrode 118 and / or the lower electrode 114 may have a relatively high acoustic impedance, even if its conductivity is not optimal. In some embodiments, the upper electrode 118 and / or the lower electrode 114 may include a material having a higher acoustic impedance and / or lower conductivity than the material of the first conductive layer 166 and / or the second conductive layer 168. The first conductive layer 166 and / or the second conductive layer 168 may have less impact on acoustic vibrations compared to BAW devices that use materials with relatively high acoustic impedance for electrodes 114, 118 to deliver electrical signals. The conductive layer 166 may be positioned above the gap 122, which can insulate the conductive layer 166 from vibration. Furthermore, the first conductive layer 166 and / or the second conductive layer 168 can reduce resistive losses compared to BAW devices that use low-conductivity materials for electrodes 114, 118 to deliver electrical signals. The BAW device 100 in Figure 2, and other embodiments disclosed herein, may include the first conductive layer 166 and / or the second conductive layer 168, similar to the BAW device 101 in Figure 3.

[0059] As shown in Figures 2, 3, and 3B, the cavity 112 may be a recess formed in the substrate 110. The lower electrode 114 may extend along a plane from the connection with the second conductive layer 168. As shown in Figure 3A, in some embodiments, the cavity 112 may be formed above the substrate 110. The top surface of the substrate 110 may be flat. The lower electrode 114 and / or the piezoelectric layer 116 may include a stepped portion having a lower region (which may be adjacent to, for example, the cavity 112) and an upper region (which may be located above, for example, the cavity 112). In some embodiments, the gap 122 may have a stepped portion (as shown in, for example, Figure 3). This stepped portion has a lower portion (which may be adjacent to, for example, a portion of the piezoelectric layer 116) and an upper portion (which may be located above that portion of the piezoelectric layer 116). As shown in Figures 2, 3A, and 3B, in some embodiments, the gap 122 may be arranged in a single plane without the step shown in Figure 3.

[0060] In some embodiments, the BAW device 101 may include an oxide layer 170 (e.g., silicon dioxide) between the substrate 110 and the lower electrode 114. The oxide layer 170 may partially or completely surround the cavity 112. Other BAW devices disclosed herein may also include an oxide layer 170. In some embodiments, the oxide layer 170 can be omitted.

[0061] The BAW device designs disclosed herein improve the Q value, for example, and k t 2 Performance is improved by improving values ​​and / or reducing spurious modes. Figure 4 shows an example of a BAW device 103. This BAW device 103 may be similar to the BAW devices 100 and / or 101 in Figures 2 and / or 3, except that it does not include gaps 122 or suspension frames 136. The BAW device 103 may include a raised frame structure 134 that can be raised by a raised frame layer 120. Figure 4A shows an example of a BAW device 103. This BAW device 103 may be similar to the BAW device 101 in Figure 3A, except that it does not include gaps 122 or suspension frames 136.

[0062] FIG. 5 shows a graph comparing the Q value for the BAW device 103 similar to that of FIGS. 4 and 4A represented by line 502 with the Q value for the BAW device 101 similar to that from FIG. 3 to FIG. 3B represented by line 504. As can be seen in FIG. 5, the BAW device 101 having the gap 122 and the suspension frame 136 can have a higher Q value and a higher maximum Q value than the BAW device 103 lacking the gap 122 and the suspension frame 136. For example, in FIG. 5, the BAW device 101 can have a maximum Q value that is about 45% higher than the maximum Q value of the BAW device 103.

[0063] FIG. 6 shows a graph comparing the conductance (dB) of the BAW device 103 similar to that of FIGS. 4 and 4A represented by line 602 with the conductance of the BAW device 101 similar to that from FIG. 3 to FIG. 3B represented by line 604. As can be seen in FIG. 6, the BAW device 101 having the gap 122 and the suspension frame 136 can have lower spurious noise than the BAW device 103 lacking the gap 122 and the suspension frame 136 (e.g., for most of the frequency range below the resonance frequency). For example, in FIG. 6, at about 1.285 GHz, the BAW device 103 can have a higher conductance than the BAW device 101. At about 1.285 GHz, the BAW device 101 can have a conductance (in dB units of spurious noise, for example) that is about 22% lower than that of the BAW device 103. Also, at about 1.54 GHz, the BAW device 103 can have a higher conductance than the BAW device 101. As shown in FIG. 6, the conductance of the BAW device 101 can be lower than the conductance of the BAW device 103 for frequencies above the resonance frequency.

[0064] FIG. 7 shows a graph comparing the admittance (dB) of the BAW device 103 similar to that of FIGS. 4 and 4A represented by line 702 with the admittance of the BAW device 101 similar to that from FIG. 3 to FIG. 3B represented by line 704. The electromechanical coupling coefficient (k t 2) is the series resonant frequency (f s ) and parallel resonant frequency (F p This can be related to the difference with ). As can be seen in Figure 7, both BAW devices 101 and 103 have an F of approximately 1.76 GHz. s The BAW device 101, having a gap 122 and a suspension frame 136, has an F of approximately 1.83 GHz. p While it may have a value, the BAW device 103, which does not have a gap 122 and a suspension frame 136, has an F of approximately 1.825 GHz. p It may have a value. That is, the BAW device 101 having a gap 122 and a suspension frame 136 has a higher k than the BAW device 103 which does not have a gap 122 and a suspension frame 136. t 2 It may have a value.

[0065] Figure 8 shows a cross-sectional view of a BAW device 105 which may be similar to the BAW device 101 of Figure 3, except as described herein. The BAW device 105 may include a support substrate 110, a cavity 112, a first electrode or lower electrode 114 disposed on the support substrate 110, a piezoelectric layer 116 disposed on the lower electrode 114, a second electrode or upper electrode 118 disposed on the piezoelectric layer 116, a raised frame structure or raised frame layer 120 disposed at least partially between the piezoelectric layer 116 and the upper electrode 120, a gap 122 between the piezoelectric layer 116 and the raised frame layer 120, and a passivation layer 124 disposed on the upper electrode 118.

[0066] The BAW device 105 may have an effective region 130 or an effective domain. The effective region 130 or effective domain may be defined by the portion of the piezoelectric layer 116 that overlaps with both the lower electrode 114 and the upper electrode 118. The main acoustic effective region 132 may be located in the central or intermediate area of ​​the effective region 130. A recessed frame region 140 may be positioned outward from the main acoustic effective region 132. A raised frame region 134 or raised frame structure may be positioned outward from the recessed frame region 140. The BAW device 105 may include a suspension frame structure or portion 136 that can be suspended above the gap 122.

[0067] The piezoelectric layer 116 of BAW device 105 may be narrower in width than some other BAW designs. Comparing Figure 8 with Figure 3, it can be seen that the piezoelectric layer 116 of BAW device 101 (Figure 3) may extend outward beyond both the upper electrode 118 and the lower electrode 114 (for example, on the left side of Figure 3), while both the upper electrode 118 and the lower electrode 114 may extend outward beyond the piezoelectric layer 116 in BAW device 105 (for example, on the left side of Figure 8). The gap 122 may be located between the portions of the upper electrode 118 and the lower electrode 114 that extend laterally beyond the piezoelectric layer 116. In some configurations, the gap 122 may separate a portion of the upper electrode 118 from a portion of the lower electrode 114. This eliminates the need to extend the piezoelectric layer 116 between the portions of the upper electrode 118 and the lower electrode 114. A portion of the upper electrode 118 may overlap with a portion of the lower electrode 114 in the area or region 174 without a piezoelectric layer present between the portions. The gap 122 may extend over part or all of the region 174. The gap 122 may extend outward beyond the piezoelectric layer 116, beyond the lower electrode 114, and / or beyond the upper electrode 118.

[0068] The upper electrode 118 may extend outward beyond the piezoelectric layer 116. In some embodiments, a portion of the upper electrode 118 may extend downward to cover at least a portion of the lateral end of the piezoelectric layer 116. The upper electrode 118 may have a first laterally extending portion (e.g., the middle or main acoustically effective region 132 of the BAW device 105), a second vertically extending portion in a first direction away from the piezoelectric layer 116 to form part of the raised frame 134 and / or suspension frame 136 (e.g., upward in Figure 8, or away from the lower electrode 114), and a third vertically extending portion in a second direction opposite to the first direction (e.g., downward in Figure 8, or towards the lower electrode 114). The second portion may be laterally outward of the first portion, and the third portion may be laterally outward of the second portion. The third portion of the upper electrode 118 may wrap around the lateral end of the piezoelectric layer 116. The third portion of the upper electrode 118 may extend further in the second direction than the second portion which extends in the first direction. In some embodiments, the lower electrode 114 may extend further laterally than the upper electrode 118.

[0069] A portion of the upper electrode 118 may be separated from a portion of the lower electrode 114 by a distance 176 smaller than the thickness 178 of the piezoelectric layer 116. In some embodiments, for example, on one side where the upper electrode 118 and / or the lower electrode 114 extend outward beyond the piezoelectric layer 116, the insulating material 180 may cover at least a portion of the lateral end of the piezoelectric layer 116. The insulating material 180 may be silicon dioxide or other suitable oxide material. In some embodiments, the insulating material 180 may be part of the oxide layer 170, the raised frame layer 120 and / or the passivation layer 124, and may be interconnected with the oxide layer 170, the raised frame layer 120 and / or the passivation layer 124 by the same material. The insulating material 170 may be placed between the lower electrode 114 and the gap 122. The insulating material 170 may be placed between the upper electrode 118 and the gap 122. In some embodiments, the insulating material 170 can cover the cross-sectional area of ​​the gap 122 on one side of the BAW device 105, except for the exposed area of ​​the piezoelectric layer 116 in the suspension frame region 136. A line extending between the upper electrode 118 and the lower electrode 114 (for example, vertically, as in the vertical direction in Figure 8 and outside the plane of the paper in Figure 1, or perpendicular to the plane defined by the piezoelectric layer 116) may intersect the gap 122 without intersecting the piezoelectric layer 116. This line may extend from the upper electrode 118 to the lower electrode 114 through the insulating material 180, through the gap 122, and through the insulating material 180. The gap 122 may extend laterally beyond one end of the upper electrode 118, beyond one end of the lower electrode 114, and / or beyond one end of the piezoelectric layer 116 (for example, on the left side of Figure 8). A portion of the gap 122 may extend downward beyond the lower surface of the upper electrode 118. A portion of the gap 122 may extend downward beyond the lower surface of the piezoelectric layer 116. Multiple portions of the gap 122 may be positioned laterally to the sides of the upper electrode 118, the piezoelectric layer 116, and the lower electrode 114. The height of the gap may be greater than the thickness of the piezoelectric layer 116. In some embodiments, a first portion of the gap 122 extends above a portion of the top of the piezoelectric layer 116, a second portion of the gap 122 extends along the lateral edge of the piezoelectric layer 116, and / or a third portion of the gap 122 extends below the bottom of the piezoelectric layer 116.

[0070] In some embodiments, the piezoelectric layer 116 may be free of steps, raised or lowered portions, and / or recesses. The piezoelectric layer may not have portions that extend beyond or penetrate the plane defined by the upper surface of the piezoelectric layer 116 in the main acoustically effective region 132. The piezoelectric layer 116 may not have portions that extend beyond or penetrate the plane defined by the lower surface of the piezoelectric layer 116 in the main acoustically effective region 132.

[0071] The BAW device 105 in Figure 8 may be more symmetrical than some other BAW designs that may improve the performance of the BAW device 105. In some embodiments, the cross-section of the piezoelectric layer 116 (shown, for example, in Figure 8) may be symmetrical, for example, along a longitudinal line (e.g., vertically in Figure 8). In some embodiments, one end of the effective area 130 may be defined by the lateral end of the piezoelectric layer 116. The effective area 130 in Figure 8 may be more symmetrical than, for example, the effective area in Figure 3. Since one end of the piezoelectric layer 116 cuts off the effective area 130 in Figure 8, the suspension frame portion 136 of the effective area 130 may have similar widths on both sides of the BAW device 105, even if one side of the upper electrode 118 and / or gap 122 (e.g., the left side in Figure 8) may extend further laterally outward than the other side of the BAW device 105 (e.g., the right side in Figure 8). With respect to a cross-section of the BAW device 105 passing through the middle or main acoustically effective region 132, the gap 122 portion (or suspension frame region 136) on one side (e.g., the left side in Figure 8) may have a width of approximately 1.25 times, approximately 1.5 times, approximately 1.75 times, approximately 2 times, approximately 2.5 times, approximately 3 times, approximately 3.5 times, approximately 4 times, approximately 4.5 times, approximately 5 times, approximately 6 times, approximately 7 times, approximately 8 times, approximately 9 times, approximately 10 times, or any value or range in between, of the gap 122 portion (or suspension frame region 136) on the other side (e.g., the right side in Figure 8). However, other configurations are also possible. In some embodiments, the width of a portion of the suspension frame 136 in the effective region 130 on one side (e.g., the left side in Figure 8) may be within approximately 50%, 40%, 30%, 25%, 20%, 15%, 10%, 7.5%, 5%, 4%, 3%, 2%, or 1% of the width of a portion of the suspension frame 136 in the effective region 130 on the other side (e.g., the right side in Figure 8). However, other configurations are also possible. In some embodiments, the first conductive material 166, the opening in the passivation layer 124, and / or the electrical interconnection between the upper electrode 118 and the first conductive layer 166 may be located laterally outside the piezoelectric layer 116 and / or laterally outside the effective region 130. The upper electrode 118 may extend further laterally on one side (for example, the left side in Figure 8) than on the other side, in order to electrically couple with, for example, the first conductive layer 166.If the piezoelectric layer 116 in Figure 8 becomes smaller, the effective region 130 is cut off on that side, and the length of the electrode 118 on which the asymmetry becomes less noticeable increases.

[0072] The BAW device may be a thin-film bulk acoustic wave resonator (FBAR) as shown in Figures 2-4 and 8. The cavity 112 may be included, for example, below the first electrode or the lower electrode 114. The cavity 112 may be filled with air in some implementations. The cavity 112 may be defined by the geometry of the first electrode 114 and / or the substrate 110. The cavity 112 may be an acoustic reflector cavity. The cavity 112 may be separated from the gap 122 disclosed herein. The cavity 112 may be located below the lower electrode 114. The gap 122 may be located above the lower surface of the lower electrode 114, above the lower electrode 114, and / or above the piezoelectric layer 116.

[0073] Although some of the BAW devices illustrated and described herein are FBAR devices, any suitable principles and advantages described herein can also be applied to solid-mount resonators (SMRs). Figure 9 is a cross-sectional view of an embodiment of a BAW device 107, which may be similar to the BAW device 101 of Figure 3, except that the BAW device 107 is an SMR and not an FBAR. In the BAW device 107 of Figure 9, a solid acoustic mirror may be placed between the first electrode 114 and the silicon substrate 110. The illustrated acoustic mirror includes an acoustic Bragg reflector. The illustrated acoustic Bragg reflector includes alternating low-impedance layers 152 and high-impedance layers 154. As an example, the Bragg reflector may include silicon dioxide layers as alternating low-impedance layers 152 and tungsten layers as high-impedance layers 154. However, other suitable materials may also be used. The raised frame layer structure of the embodiment of Figure 9 may have similar features and functions to the raised frame or suspension frame structure of the embodiment of Figure 3.

[0074] Figure 10 is a cross-sectional view of a BAW device 109 in one embodiment, which may be similar to the BAW device 103 in Figure 8, except that the BAW device 107 is an SMR instead of an FBAR. In the BAW device 109 of Figure 10, a solid acoustic mirror may be positioned between the first electrode 114 and the silicon substrate 110. The illustrated acoustic mirror includes an acoustic Bragg reflector. The illustrated acoustic Bragg reflector includes alternating low-impedance layers 152 and high-impedance layers 154. As an example, the Bragg reflector may include silicon dioxide layers as alternating low-impedance layers 152 and tungsten layers as high-impedance layers 154. However, other suitable materials may also be used. The raised frame layer structure of the embodiment in Figure 10 may have similar features and functions to the raised frame or suspension frame structure in the embodiment in Figure 8. Any of the other embodiments disclosed herein may be an FBAR or an SMR. For example, an embodiment including a cavity 112 may include a Bragg reflector similar to, for example, those in Figures 9 and 10.

[0075] Figure 11 is a cross-sectional view of a BAW device 111 of one embodiment, which may be similar to other BAW devices disclosed herein, except that the BAW device 111 may include a raised frame layer 121 positioned on the upper electrode 118. The raised frame layer 121 may be a material with relatively high acoustic impedance. The raised frame layer 121 may include a material with relatively high density. For example, the raised frame layer 121 may include molybdenum (Mo), tungsten (W), ruthenium (Ru), platinum (Pt), iridium (Ir), Ir / Pt, etc., or any suitable alloy of any of these materials. The raised frame layer 121 may be a metallic layer. Alternatively, the raised frame layer 121 may be a suitable nonmetallic material having relatively high density and / or acoustic impedance. The density and / or acoustic impedance of the raised frame layer 121 may be the same as, or greater than, the density and / or acoustic impedance of the lower electrode 114, the upper electrode 118, or the piezoelectric layer 116.

[0076] In some examples, the raised frame structure 121 may be made of the same material as the lower electrode 114 and / or upper electrode 118 of the BAW device 111. In some implementation examples, the raised frame layer 121 may be adjacent to the upper electrode 118. The upper electrode 118 may have a substantially uniform thickness, but in some cases it may be inclined (e.g., downward or toward the piezoelectric layer 116). The raised frame layer 121 may be a thickened region of the same material that forms the upper electrode 118. The upper electrode 118 and the raised frame layer 121 may be formed by different processing steps, and in some cases there may be a resulting identifiable transition between the upper electrode 118 and the raised frame layer 121 of the same material. However, there may be implementation examples in which there is no identifiable transition between the upper electrode and the raised frame layer 121. A passivation layer 124 may be placed on top of the upper electrode 118 and / or on top of the raised frame layer 121. The raised frame layer 121 may overlap the gap 122 at least partially, for example, in the effective region 130. The raised frame layer 121 may be positioned above the upper electrode 118. In some embodiments, the BAW device 111 does not include the raised frame layer 120. The gap 122 may be formed between the piezoelectric layer 116 and the upper electrode 118. In some embodiments, the BAW device 111 may include a suspension frame 136 suspended by the gap 122.

[0077] Figure 12 is a cross-sectional view of a BAW device 113 of one embodiment, which may be similar to other BAW devices disclosed herein, except that the BAW device 113 may have a double-layer raised frame structure that may include a first raised frame layer 120 and a second raised frame layer 121. The density and / or acoustic impedance of the first raised frame layer 120 may be lower than that of the lower electrode 114, the upper electrode 118, the piezoelectric layer 116, and / or the second raised frame layer 121. The second raised frame layer 121 may overlap the first raised frame layer 120 at least partially in the effective region 130 of the BAW device 113, for example. The second raised frame layer 121 may be located above the upper electrode 118. The upper electrode 118 may be located between the first raised frame layer 120 and the second raised frame layer 121. The first raised frame layer 120, the upper electrode 118, and the second raised frame layer 121 may be positioned above the gap 122. The second raised frame layer 121 may be a material with relatively high acoustic impedance. The second raised frame layer 121 may contain a material with relatively high density. For example, the second raised frame layer 121 may contain molybdenum (Mo), tungsten (W), ruthenium (Ru), platinum (Pt), iridium (Ir), etc., or any suitable alloy of any of these materials. The second raised frame layer 121 may be a metallic layer. Alternatively, the second raised frame layer 121 may be, for example, a suitable non-metallic material with relatively high density. The density and / or acoustic impedance of the second raised frame layer 121 may be the same as, or greater than, the density and / or acoustic impedance of, the lower electrode 114, the upper electrode 118, the piezoelectric layer 116, and / or the first raised frame layer 120 of the BAW device 113. In some examples, the second raised frame structure 121 may be made of the same material as the lower electrode 114 and / or the upper electrode 118. In some implementation examples, the second raised frame layer 121 may be adjacent to the upper electrode 118. The upper electrode 118 may have a substantially uniform thickness, but in some cases it may be inclined (e.g., downward or toward the piezoelectric layer 116). The second raised frame layer 121 may be a thickened region of the same material that forms the upper electrode 118.The upper electrode 118 and the second raised frame layer 121 may be formed by different processing steps, and in some cases, there may be a resulting identifiable transition between the upper electrode 118 and the second raised frame layer 121 made of the same material. However, there may be implementation examples in which there is no identifiable transition between the upper electrode and the second raised frame layer 121. A passivation layer 124 may be placed on top of the upper electrode 118 and / or on top of the second raised frame layer 121.

[0078] Many variations are possible. In some embodiments, the raised frame layer 120 and / or gap 122 may be located in different positions than in the embodiments illustrated herein. The raised frame layer 120 and / or gap 122 are located between the first electrode or lower electrode 114 and the piezoelectric layer 116. Figure 12A shows a cross-sectional view of a bulk acoustic wave device 115 of one embodiment. The BAW device 115 may be the same as in other embodiments disclosed herein, except as described. The gap 122 may be located below the piezoelectric layer 116. The gap 122 may be located between the piezoelectric layer 116 and the substrate 110, or between the piezoelectric layer 116 and the lower electrode 114. The suspension frame portion 136 may be located above the gap 122. The internal raised frame portion 138 may be located inward of the suspension frame portion 136 and may correspond to a portion that is lifted by the raised frame layer 120 but is not located above the gap 122. The raised frame layer 120 may be located on top of the piezoelectric layer 116, for example, between the piezoelectric layer 116 and the upper electrode 118. In some embodiments, the second raised frame layer 123 may be located below the piezoelectric layer 116, for example, between the piezoelectric layer 116 and the lower electrode 114 or the substrate 110. The second raised frame layer 123 may be silicon dioxide or another oxide material, or some other insulating material or low acoustic impedance material. The gap 122 may be located on top of the second raised frame layer 123. The second raised frame layer 123 may be located between the gap 122 and the first electrode or the lower electrode 114. In some embodiments, the second raised frame layer 123 may be omitted. In some embodiments, the raised frame layer 120 may be omitted. For example, the layer 123 below the piezoelectric layer 116 may be the raised frame layer, and in some cases, the raised frame layer may not be located above the piezoelectric layer 116. In some embodiments, the raised frame layer 123 may extend inward beyond the gap 122. The raised frame layer 123 may be in physical contact with the piezoelectric layer 116 and the first electrode 114, for example in the internal raised frame portion 138. The raised frame layer 123 may be in contact with the lower electrode 114 and may be spaced apart from the piezoelectric layer 116 by the gap 122 (for example in the suspension frame portion 136).The raised frame layer 123 may be in contact with the piezoelectric layer 116, and may be spaced apart from the lower electrode 114 by a gap 122 in the suspension frame portion 136, for example. The piezoelectric layer 116 may have a stepped cross-sectional shape due to the raised frame layer 123 and / or the gap 122. The piezoelectric layer 116 may have one or more steps that are lifted by the raised frame layer 123 and / or the gap 122. In some embodiments, either the raised frame layer 120 or the gap 122 may be located between the piezoelectric layer 116 and the lower electrode 114, and the other of the gap 122 and the raised frame layer 120 may be located between the piezoelectric layer 116 and the upper electrode 118.

[0079] Furthermore, in the BAW device 113 of Figures 12 and 12A, the recessed frame region 140 is omitted. For example, the passivation layer 124 may have a substantially uniform thickness inside the raised frame region 138 and / or the suspension frame region 136. In some embodiments, the intermediate portion or primary acoustically effective region of the BAW device may be the area inside the raised frame region 138 and / or the suspension frame region 136. In some other embodiments, the passivation layer 124 may be omitted. In some embodiments, the BAW device 113 may have a recessed frame region 140, similar to other embodiments disclosed herein.

[0080] Various features of the BAW devices shown in Figures 2-4 and 8-12 can be combined. For example, any of these BAW devices may be an SMR instead of an FBAR, or an FBAR instead of an SMR. The BAW devices in Figures 2-4 and 8-12 may have a raised frame layer 120 and / or gap 122 positioned between the lower electrode 114 and the piezoelectric layer 116. Any of these BAW devices may have a raised frame layer 121 positioned above the upper electrode 118 (as shown, for example, in Figure 11). Any of these BAW devices may include a multilayer raised frame structure having a first raised frame layer 120 and a second raised frame layer 121 (as shown, for example, in Figure 12). Any of these BAW devices may omit the recessed frame region 140 (as shown, for example, in Figure 12), or the passivation layer 124. The BAW device may include any combination of these features.

[0081] The BAW devices disclosed herein can be manufactured using any suitable technique or process. In some cases, a material or layer may be deposited by any suitable technique, and multiple portions of the deposited material may be removed, for example, by etching, while other portions of the deposited material may be retained by shielding the material from etching using a mask. Various other manufacturing processes may also be used.

[0082] While exemplary manufacturing processes are described, other variations are possible. In some embodiments, a substrate (e.g., substrate 110) such as a silicon (Si) wafer is given. A passivation layer (e.g., oxide layer 170) may be formed (e.g., deposited) in contact with the substrate, on or above the substrate. The passivation layer may be silicon dioxide. A cavity sacrificial layer (e.g., to form the shape of a cavity 112) may be formed (e.g., deposited and patterned) in contact with the substrate or the passivation layer, on or above the substrate or the passivation layer. A membrane layer may be formed (e.g., deposited) in contact with the cavity sacrificial layer, on or above the cavity sacrificial layer. The membrane layer may be the same material as the passivation layer (e.g., silicon dioxide). A conductive layer (e.g., metal) may be formed (e.g., deposited and patterned) in contact with or on a substrate, cavity sacrificial material, or membrane, or above the substrate, cavity sacrificial material, or membrane, to provide, for example, a lower electrode 114. A piezoelectric layer 116 may be formed (e.g., deposited) in contact with or above the conductive layer of the lower electrode 114. A suspension frame sacrificial layer may be formed (e.g., deposited) in contact with or above the piezoelectric layer 116. The suspension frame sacrificial layer may be patterned to provide the shape of one or more gaps 122. A first raised frame layer may be formed (e.g., deposited and patterned) to provide a first raised frame layer 120. For example, a conductive layer (e.g., metal) may be formed (e.g., deposited) in contact with and on or above the first raised frame layer 120 or suspension frame sacrificial material in order to form the upper electrode 118. In some embodiments, a second raised frame layer 121 may be formed (e.g., deposited and patterned) in contact with and on or above the upper electrode 118. The conductive layer may be formed (e.g., patterned) to give the shape of the upper electrode 118. The piezoelectric material may be formed (e.g., patterned) to give the shape of the piezoelectric layer 116.For example, a passivation layer 124 may be formed (e.g., deposited) in contact with the upper electrode 118 or the second raised frame layer 121, or above the upper electrode 118 or the second raised frame layer 121. In some embodiments, the passivation layer may be patterned to form a recessed frame region 140. In some embodiments, the passivation layer 124 may be formed (e.g., patterned) to provide an opening. A conductive (e.g., metallic) layer may be formed (e.g., deposited or patterned) such that the conductive layer 166 extends into the opening of the passivation layer and contacts the upper electrode 118 or the second raised frame layer 121. A conductive material may also form a second conductive layer 168 having electrical contacts with the lower electrode 114. In some embodiments, contacts (e.g., metal pads) may be formed that can be configured to provide signals to and from the lower electrode 114 (e.g., via the conductive layer 168) and to and / or from the upper electrode (e.g., via the conductive layer 166). A cavity sacrificial layer may be removed to form a cavity 112. A suspension frame sacrificial layer may be removed to form one or more gaps 122. In some embodiments, the cavity sacrificial layer and the suspension frame sacrificial layer may be removed together, for example, in the same process step or simultaneously.

[0083] Figure 12B shows a plan view of a bulk elastic device according to one embodiment. Figure 12C shows a cross-sectional view of the BAW device of Figure 12B along the line B-B'. The BAW device 101 may have a substrate 100, a passivation layer or oxide layer 170, a cavity sacrificial layer 182, a lower electrode layer 114, a piezoelectric layer 116, a suspension frame sacrificial layer 184, a raised frame layer 120, an upper electrode layer 118, a passivation layer 124, and / or a conductive layer 166. These layers may be deposited and / or patterned to form the shapes and configurations disclosed herein. In the cross-section shown in Figure 12C, both the cavity sacrificial layer 182 and the suspension frame sacrificial layer 184 may be exposed so that the sacrificial layers can be removed (e.g., by dry etching or wet etching or any other suitable technique). Since both the cavity sacrificial layer 182 and the suspension frame sacrificial layer 184 are exposed, they may be removed during and / or simultaneously in the same processing step. In some embodiments, the cavity sacrificial layer 182 may extend into the gap or space between the piezoelectric layer 116 and the substrate 110, or extend laterally beyond said gap or space. The suspension frame sacrificial layer 184 may extend laterally into the gap or space between the piezoelectric layer 116 and the raised frame layer 120, or extend laterally beyond said gap or space.

[0084] The BAW resonators disclosed herein can be implemented in elastic wave filters. In a given application, the elastic wave filters may be band-pass filters arranged to pass radio frequency bands and attenuate frequencies outside of said radio frequency bands. Two or more elastic wave filters can be coupled together at a common node and arranged as a multiplexer, such as a duplexer.

[0085] Figure 13 is a schematic diagram of an example elastic wave ladder filter 220. The elastic wave ladder filter 220 may be a transmit filter or a receive filter. The elastic wave ladder filter 220 may be a band-pass filter arranged to filter radio frequency signals. The elastic wave filter 220 may include series resonators R1, R3, R5, R7, and R9 and shunt resonators R2, R4, R6, and R8 coupled between the radio frequency input / output port RFI / O and the antenna port ANT. The radio frequency input / output port RFI / O may be the transmit port in a transmit filter or the receive port in a receive filter. One or more of the illustrated elastic wave resonators may be bulk elastic wave resonators following any suitable principles and advantages described herein. The elastic wave ladder filter may include any suitable number of series resonators and any suitable number of shunt resonators.

[0086] The elastic wave filters may be arranged in a lattice topology or any other suitable filter topology such as a hybrid ladder and lattice topology. Bulk elastic wave resonators conforming to any suitable principles and advantages disclosed herein may be implemented in a band-pass filter. In some other applications, bulk elastic wave resonators conforming to any suitable principles and advantages disclosed herein may be implemented in a band-stop filter.

[0087] Figure 14 is a schematic diagram of an example duplexer 230. The duplexer 230 may include a transmit filter 231 and a receive filter 232 coupled to each other at the antenna node ANT. A shunt inductor L1 may be connected to the antenna node ANT. Both the transmit filter 231 and the receive filter 232 may be elastic wave ladder filters in the duplexer 230.

[0088] The transmit filter 131 can filter the radio frequency signal and provide the filtered radio frequency signal to the antenna node ANT. A series inductor L2 may be coupled between the transmit input node TX and the elastic wave resonator of the transmit filter 131. The illustrated transmit filter 131 may include elastic wave resonators T01 to T09. One or more of these resonators may be bulk elastic wave resonators according to any suitable principles and advantages disclosed herein. The illustrated receive filter may include elastic wave resonators R01 to R09. One or more of these resonators may be bulk elastic wave resonators according to any suitable principles and advantages disclosed herein. The receive filter can filter the radio frequency signal received at the antenna node ANT. A series inductor L3 may be coupled between the resonator and the receive output node RX. The receive output node RX of the receive filter provides the radio frequency received signal.

[0089] Figure 15 is a schematic diagram of a multiplexer 235 including an elastic wave filter according to one embodiment. The multiplexer 235 includes a plurality of filters 236A to 236N that are coupled together at a common node COM. The plurality of filters may include any appropriate number of filters. For example, it may include three filters, four filters, five filters, six filters, seven filters, eight filters, or more filters. Some or all of the plurality of elastic wave filters may be elastic wave filters. The illustrated filters 236A, 236B, and 236N may each be coupled between the common node COM and the input / output nodes RFI / O1, RFI / O2, and RFI / ON, respectively.

[0090] In some examples, all filters of the multiplexer 235 may be receive filters. In some other examples, all filters of the multiplexer 235 may be transmit filters. In various applications, the multiplexer 235 may include one or more transmit filters and one or more receive filters. Thus, the multiplexer 235 may include any appropriate number of transmit filters and any appropriate number of receive filters. Each of the illustrated filters may be a band-pass filter having a different passband.

[0091] Multiplexer 235 is illustrated to have hard multiplexing with filters 236A-236N having a fixed connection to a common node COM. In some other applications, one or more of these filters of the multiplexer may be electrically connected to the common node via their respective switches. Any such filter may include a bulk acoustic wave resonator following any suitable principle and advantages disclosed herein.

[0092] The first filter 236A may be an elastic wave filter arranged to filter radio frequency signals with a first passband. The first filter 236A may include one or more bulk elastic wave resonators according to any suitable principles and advantages disclosed herein. The second filter 236B has a second passband. In some embodiments, the raised frame structures of one or more bulk elastic wave resonators of the first filter 236A may move the raised frame modes of one or more bulk elastic wave resonators away from the second passband. This can increase the reflection coefficient (gamma) of the first filter 236A in the passband of the second filter 236B. The raised frame structures of the bulk elastic wave resonators of the first filter 236A may also move the raised frame modes away from one or more other filters of the multiplexer 235.

[0093] In a given example, the common node COM of the multiplexer 235 can be arranged to receive a carrier aggregation signal that includes at least a first carrier associated with the first passband of the first filter 236A and a second carrier associated with the second passband of the second filter 236B. The multilayer raised frame structure of the bulk acoustic wave resonator of the first filter 236A can maintain and / or increase the reflection coefficient of the first filter 236A in the second passband of the second filter 236B associated with the second carrier of the carrier aggregation signal.

[0094] The filters 236B to 236N of the multiplexer 235 may include one or more acoustic wave filters, one or more acoustic wave filters including at least one bulk acoustic wave resonator having a raised frame structure, one or more LC filters, one or more hybrid acoustic wave LC filters, or any suitable combination thereof.

[0095] The raised-frame bulk acoustic wave resonators disclosed herein may be implemented in various package modules. Several examples of package modules in which any suitable principles and advantages of the bulk acoustic wave device disclosed herein can be implemented are described below. The exemplary package module may include a package enclosing the illustrated circuit elements. The illustrated circuit elements may be arranged on a common package substrate. The package substrate may be, for example, a multilayer substrate. Figures 16, 17A, 17B and 18 are schematic block diagrams of exemplary package modules according to a given embodiment. A given example of a package module may include one or more radio frequency amplifiers, such as one or more power amplifiers and / or one or more low-noise amplifiers. Any suitable combination of the features of these modules can be implemented together. Although duplexers are shown in the examples of package modules in Figures 16 and 17, any other suitable multiplexer, including multiple acoustic wave filters coupled to a common node, may be implemented instead of one or more duplexers. For example, a quadplexer may be implemented in a given application. Alternatively or additionally, one or more filters in the packaged module may be arranged as transmit or receive filters not included in the multiplexer.

[0096] Figure 16 is a schematic block diagram of an example module 240 including duplexers 241A-241N and an antenna switch 242. One or more filters of duplexers 241A-241N may include any suitable number of multilayer raised-frame bulk acoustic wave resonators that conform to any suitable principles and advantages described herein. Any suitable number of duplexers 241A-241N may be implemented. The antenna switch 242 may have a certain number of outputs corresponding to the number of duplexers 241A-241N. The antenna switch 242 can electrically couple selected duplexers to the antenna ports of module 240.

[0097] Figure 17A is a schematic block diagram of an example module 250 including a power amplifier 252, a radio frequency switch 254, and duplexers 241A-241N according to one or more embodiments. The power amplifier 252 can amplify radio frequency signals. The radio frequency switch 254 may be a multi-throw radio frequency switch. The radio frequency switch 254 can electrically couple the output of the power amplifier 252 to a selected transmit filter of the duplexers 241A-241N. One or more filters of the duplexers 241A-241N may include any suitable number of raised-frame bulk acoustic wave resonators following any suitable principles and advantages described herein. Any suitable number of duplexers 241A-241N may be implemented.

[0098] Figure 17B is a schematic block diagram of an example module 255 including filters 256A-256N, a radio frequency switch 257, and a low-noise amplifier 258 according to one or more embodiments. One or more of the filters 256A-256N may include any suitable number of raised-frame bulk acoustic wave resonators according to any suitable principles and advantages disclosed herein. Any suitable number of filters 256A-256N may be implemented. The illustrated filters 256A-256N may be used as receiving filters. In some embodiments (not shown), one or more of the filters 256A-256N may be included in a multiplexer that also includes a transmitting filter. The radio frequency switch 257 may be a multi-throw radio frequency switch. The radio frequency switch 257 can electrically couple the output of a selected filter from the filters 256A-256N to the low-noise amplifier 257. In some embodiments (not shown), multiple low-noise amplifiers may be implemented. Module 255 may include diversity receiving functionality in a given application.

[0099] Figure 18 is a schematic block diagram of an example module 260, which includes a power amplifier 252, a radio frequency switch 254, a duplexer 241 including a raised frame bulk acoustic wave device according to one or more embodiments, and an antenna switch 242. Module 260 may include multiple elements of module 240 and multiple elements of module 250.

[0100] One or more filters having any appropriate number of raised-frame bulk elastic devices may be implemented in various wireless communication devices. Figure 19A is a schematic block diagram of an example of a wireless communication device 270 including a filter 273 having one or more raised-frame bulk elastic wave resonators according to any appropriate principles and advantages disclosed herein. The wireless communication device 270 may be any appropriate wireless communication device. For example, the wireless communication device 270 may be a mobile phone such as a smartphone. As shown in the figure, the wireless communication device 270 includes an antenna 271, a radio frequency (RF) front end 272 including a filter 273, an RF transceiver 274, a processor 275, memory 276, and a user interface 277. The antenna 271 can transmit an RF signal given by the RF front end 272. The antenna 271 can provide the RF signal received to the RF front end 272 for processing.

[0101] The RF front-end 272 may include one or more power amplifiers, one or more low-noise amplifiers, an RF switch, a receiving filter, a transmitting filter, a duplex filter, a multiplexer filter, a diplexer filter, or other frequency multiplexing circuits, or any suitable combination thereof. The RF front-end 272 can transmit and receive RF signals associated with any suitable communication standard. Any of the multilayer raised-frame bulk acoustic wave resonators disclosed herein may be implemented in the filter 273 of the RF front-end 272.

[0102] The RF transceiver 274 can supply an RF signal to the RF front end 272 for amplification and / or other processing. The RF transceiver 274 can also process the supplied RF signal through the low-noise amplifier of the RF front end 272. The RF transceiver 274 communicates with the processor 275. The processor 275 may be a baseband processor. The processor 275 can provide any suitable baseband processing functions for the wireless communication device 270. Memory 276 is accessible by the processor 275. Memory 276 can store any suitable data for the wireless communication device 270. The processor 275 also communicates with the user interface 277. The user interface 277 may be any suitable user interface, such as a display.

[0103] Figure 19B is a schematic diagram of a wireless communication device 280, which includes a filter 273 in the radio frequency front end 272 and a second filter 283 in the diversity receiving module 282. The wireless communication device 280 is similar to the wireless communication device 270 in Figure 19A, except that the wireless communication device 280 also includes diversity receiving functionality. As shown in Figure 19B, the wireless communication device 280 may include a diversity antenna 281, a diversity module 282 which includes a plurality of filters 283 configured to process signals received by the diversity antenna 281, and a transceiver 274 which communicates with both the radio frequency front end 272 and the diversity receiving module 282. One or more of the plurality of second filters 283 may include a bulk acoustic wave resonator having a multilayer raised frame structure according to any suitable principles and advantages disclosed herein.

[0104] The bulk acoustic wave devices disclosed herein may include filters and / or multiplexers arranged to filter radio frequency signals in the fifth-generation (5G) nu-radio (NR) operating band within frequency range 1 (FR1). FR1 can range from 410 megahertz (MHz) to 7.125 gigahertz (GHz), as specified, for example, in current 5G NR specifications. The filters arranged to filter radio frequency signals in the FR1 operating band of 5G NR may include one or more bulk acoustic wave resonators implemented according to any suitable principles and advantages disclosed herein.

[0105] The 5GNR carrier aggregation specification may present technical challenges. For example, 5G carrier aggregation may have a wider bandwidth and / or channel spacing than fourth-generation (4G) Long-Term Evolution (LTE) carrier aggregation. The carrier aggregation bandwidth in a given 5GFR1 application may be in the range of 120 MHz to 400 MHz, such as 120 MHz to 200 MHz. The carrier spacing in a given 5GFR1 application may be up to 100 MHz. Bulk acoustic wave resonators having the raised frame structure disclosed herein can achieve low insertion loss and low gamma loss in some embodiments. The frequency of the raised frame mode in such a bulk acoustic wave resonator can be moved to be significantly away from the resonant frequency of the bulk acoustic wave resonator. Thus, the raised frame mode may exist outside the carrier aggregation bandwidth even when there is a wide carrier aggregation bandwidth and / or channel spacing within the FR1 of the 5G specification. This allows for the reduction and / or elimination of gamma degradation in the operating bandwidth of other carriers in carrier aggregation. In some cases, gamma can increase in the operating bandwidth of other carriers in carrier aggregation.

[0106] Any of the embodiments described above can be implemented in connection with a portable device such as a cellular handset. The principles and benefits of these embodiments can be used for any system or device, such as any uplink wireless communication device, that can benefit from any of the embodiments described herein. The teachings herein are applicable to a variety of systems. Although this disclosure includes some exemplary embodiments, the teachings described herein are applicable to a variety of structures. Any of the principles and benefits described herein can be implemented in connection with an RF circuit configured to process signals in a frequency range of about 30 kHz to 300 GHz, such as a frequency range of about 450 MHz to 8.5 GHz.

[0107] Multiple aspects of this disclosure can be implemented in various electronic devices. Examples of electronic devices may include, but are not limited to, consumer electronic products, components of consumer electronic products such as packaged radio frequency modules, uplink wireless communication devices, wireless communication infrastructure, and electronic test equipment. Examples of electronic devices may include, but are not limited to, portable telephones such as smartphones, wearable computing devices such as smartwatches or earpieces, telephones, televisions, computer monitors, computers, modems, handheld computers, laptop computers, tablet computers, microwave ovens, refrigerators, automotive electronic systems such as automotive electronic systems, stereo systems, digital music players, radios, cameras such as digital cameras, portable memory chips, washing machines, dryers, washer / dryer machines, photocopiers, facsimile machines, scanners, multifunction peripheral devices, wristwatches, and clocks. Furthermore, electronic devices may also include unfinished products.

[0108] Unless the context explicitly indicates otherwise, throughout the specification and claims, terms such as “includes,” “equip,” and so on should generally be interpreted in a comprehensive sense, the opposite of an exclusive or exhaustive sense, i.e., “includes but not limited to.” Unless specifically stated or understood otherwise in the context in which they are used, conditional language used herein, in particular, such as “can,” “may,” “may,” “for example,” and “like,” is generally intended to mean that a given embodiment includes a given feature, element, and / or state, while other embodiments do not. The term “combined,” as used herein, refers to two or more elements that can be directly connected or connected via one or more intermediate elements. Similarly, the term “connected,” as used herein, refers to two or more elements that can be directly connected or connected via one or more intermediate elements. In addition, where used herein, the terms “here,” “above,” “below,” and similar terms refer to the entire application and not to any particular part of the application. Where the context allows, the terms used in the detailed explanations above, which use singular or plural numbers, may also include singular or plural numbers.

[0109] While certain embodiments have been described, these embodiments are presented only as examples and are not intended to limit the scope of this disclosure. In fact, the novel resonators, devices, modules, apparatus, methods, and systems described herein can be embodied in a variety of other forms. Furthermore, various omissions, substitutions, and modifications in the forms of resonators, filters, multiplexers, devices, modules, apparatus, methods, and systems described herein can be made without departing from the essence of this disclosure. For example, while blocks are presented in a given arrangement, alternative embodiments may perform similar functions with different components and / or circuit topologies, and some blocks may be deleted, moved, added, subdivided, combined, and / or modified. Each of these blocks may be implemented in a variety of different forms. Any suitable combination of elements and / or operations of the various embodiments described above can be combined to give further embodiments. The appended claims and their equivalents are intended to cover forms or modifications that fall within the scope and essence of this disclosure.

Claims

1. 1. A bulk acoustic wave device comprising: A first electrode; A second electrode; a piezoelectric layer between the first electrode and the second electrode; an effective area where the piezoelectric layer overlaps the first electrode and the second electrode, the effective area including an intermediate area; a raised frame structure outside the intermediate area of ​​the effective area; Including, A bulk acoustic wave device, wherein the raised framework includes a gap between the first electrode and the second electrode such that at least a portion of the raised framework forms a suspension frame suspended above the gap.

2. the piezoelectric layer overlies the first electrode; the second electrode overlies the piezoelectric layer; The bulk acoustic wave device of claim 1 , wherein the gap exists between the first electrode and the piezoelectric layer.

3. the piezoelectric layer overlies the first electrode; the second electrode overlies the piezoelectric layer; The bulk acoustic wave device of claim 1 , wherein the gap exists between the second electrode and the piezoelectric layer.

4. The bulk acoustic wave device of claim 1 , wherein the raised frame structure includes an interior raised frame portion outside the intermediate area and inside the suspension frame.

5. The bulk acoustic wave device of claim 4 , wherein the suspension frame has a height greater than a height of the inner raised frame portion.

6. The bulk acoustic wave device of claim 4 , wherein the raised frame structure includes a raised frame layer extending over at least a portion of the gap.

7. The bulk acoustic wave device of claim 6 , wherein the raised frame layer extends inwardly into the gap to form at least a portion of the inner raised frame portion of the raised frame structure.

8. The bulk acoustic wave device of claim 6 , wherein the raised frame layer has a lower acoustic impedance than at least one of the first electrode, the second electrode, and the piezoelectric layer.

9. The bulk acoustic wave device of claim 1 , further comprising a passivation layer over the first electrode, the second electrode, the piezoelectric layer, and the raised framework.

10. a recessed frame region between the raised frame structure and the intermediate area; The bulk acoustic wave device of claim 9 , wherein the passivation layer is thinner in the recessed frame region than in the intermediate area.

11. further comprising a conductive layer disposed over a portion of the passivation layer; The bulk acoustic wave device of claim 9 , wherein a portion of the conductive layer extends into the opening in the passivation layer to electrically contact the second electrode.

12. The bulk acoustic wave device of claim 11 , wherein the opening in the passivation layer is directly above the gap.

13. The bulk acoustic wave device of claim 1 , wherein a portion of the gap extends laterally outward beyond one end of the piezoelectric layer.

14. The bulk acoustic wave device of claim 1 , wherein a portion of the gap extends downward beyond the lower surface of the piezoelectric layer.

15. a portion of the first electrode extending laterally beyond one end of the piezoelectric layer; a portion of the second electrode extending laterally beyond the one end of the piezoelectric layer; The bulk acoustic wave device of claim 1 , wherein the gap is disposed between the portion of the first electrode and the portion of the second electrode.

16. The bulk acoustic wave device of claim 15 , wherein the distance between the portion of the first electrode and the portion of the second electrode is less than a thickness of the piezoelectric layer.

17. 1. A bulk acoustic wave device comprising: A first electrode; A second electrode; a piezoelectric layer between the first electrode and the second electrode; a raised frame structure including a suspension frame portion above the gap existing between the first electrode and the second electrode, and an internal raised frame portion laterally inward of the suspension frame portion; A bulk acoustic wave device comprising:

18. the raised framework includes a raised frame layer between the first electrode and the second electrode; the inner raised frame portion includes a first portion of the raised frame layer that does not overlie the gap; The bulk acoustic wave device of claim 17 , wherein the suspension frame portion includes a second portion of the raised frame layer overlying the gap.

19. 20. The bulk acoustic wave device of claim 18, wherein the raised frame layer has a lower acoustic impedance than at least one of the first electrode, the second electrode, and the piezoelectric layer.

20. 20. The bulk acoustic wave device of claim 17, further comprising a passivation layer over the first electrode, the second electrode, the piezoelectric layer, and the raised framework.

21. further comprising a conductive layer disposed over a portion of the passivation layer; 21. The bulk acoustic wave device of claim 20, wherein a portion of the conductive layer extends into the opening in the passivation layer to electrically contact the second electrode.

22. 22. The bulk acoustic wave device of claim 21, wherein the opening in the passivation layer is directly above the gap.

23. The bulk acoustic wave device of claim 17 , wherein a portion of the gap extends laterally outward beyond one end of the piezoelectric layer.

24. a portion of the first electrode extending laterally beyond one end of the piezoelectric layer; a portion of the second electrode extending laterally beyond one end of the piezoelectric layer; The bulk acoustic wave device of claim 17 , wherein the gap is disposed between the portion of the first electrode and the portion of the second electrode.

25. 25. The bulk acoustic wave device of claim 24, wherein the distance between the portion of the first electrode and the portion of the second electrode is less than a thickness of the piezoelectric layer.

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