PIEZOELECTRIC MEMS DEVICE WITH THERMAL COMPENSATION FROM DIFFERENT MATERIAL PROPERTIES
A piezoelectric microelectromechanical systems device is provided, having a first piezoelectric layer, a first metal layer including a first metal, a second metal layer including a second metal, the first and second metals having different properties to compensate deflection due to thermal stress of any or all of the piezoelectric layer, the first metal layer, and second metal layer and a substrate including at least one wall defining a cavity and the at least one wall supporting the layers. The method for making the piezoelectric microelectromechanical systems device is also provided.
This application is based upon and claims the benefit of priority from U.S. Provisional Patent Application No. 63/249,449 filed on Sep. 28, 2021. Any and all applications for which a foreign or domestic priority claim is identified in the Application Data Sheet as filed with the present application are hereby incorporated by reference under 37 CFR 1.57. The entire contents of each of the above-listed items is hereby incorporated into this document by reference and made a part of this specification for all purposes, for all that each contains.
BACKGROUND FieldEmbodiments of the invention relate to a piezoelectric micromechanical systems (MEMS) device.
Description of the Related TechnologyA MEMS microphone is a type of micro-machined electromechanical device used to convert sound pressure (e.g., voice sound) to an electrical signal (e.g., voltage). MEMS microphones are useful for mobile devices, headsets, smart speakers and other voice-interface devices or systems, for example. Conventional capacitive MEMS microphones suffer from high power consumption (e.g., large bias voltage) and reliability, for example when used in a harsh environment (e.g., when exposed to dust and/or water).
Piezoelectric MEMS microphones can be used to address the deficiencies of capacitive MEMS microphones. Piezoelectric MEMS microphones offer a constant listening capability while consuming almost no power (e.g., no bias voltage is needed), are robust and immune to water and dust contamination.
Piezoelectric MEMS microphones work on the principle of the piezoelectric effect, converting acoustic signals to electric signals when sound waves vibrate the piezoelectric sensor. The sound waves bend the piezoelectric film layers of a cantilevered beam or membrane, causing stress and strain, resulting in charges being generated in the piezoelectric film layers. The charges are converted to voltage as an output signal, by the placement of one or more electrodes on the piezoelectric film layers. Performance of such microphones therefore depends on the membrane or cantilever's ability to respond to acoustic waves. The present disclosure describes how to achieve improved sensitivity of such microphones, for example.
SUMMARYAccording to an embodiment there is provided a piezoelectric microelectromechanical systems device, comprising a first piezoelectric layer, a first metal layer adjacent the first piezoelectric layer and comprising a first metal, a second metal layer comprising a second metal, the first and second metals having different properties to compensate for deflection due to thermal stress of any or all of the piezoelectric layer, the first metal layer, and second metal layer and a substrate including at least one wall defining a cavity and the at least one wall supporting the layers.
In some examples the device comprises a third metal layer.
In some examples the first, second and third metal layers are upper, lower and middle layers respectively.
In some examples two of the first, second and third metal layers comprise different thicknesses from each other.
In some examples the third metal layer is composed of a different metal from the first metal layer and the second metal layer.
In some examples the third metal is composed of the same metal of the first metal layer and/or second metal layer.
In some examples the device comprises a second piezoelectric layer adjacent the first or second metal layer and the third metal layer is adjacent the second piezoelectric layer.
In some examples the first and second piezoelectric layers have different thicknesses from each other.
In some examples the piezoelectric layer and first and second metal layers are alternated.
In some examples the first piezoelectric layer, second piezoelectric layer, first metal layer, second metal layer and third metal layer are alternated.
In some examples, the layers are arranged in a stack that alternates between metal and piezoelectric material.
In some examples the piezoelectric and metal layers form a membrane that spans the cavity.
In some examples the piezoelectric and metal layers form a cantilever that extends across at least a portion of the cavity.
In some examples the second metal layer is composed of a metal with a higher Young's modulus than the first metal layer, and the second metal layer is an upper metal layer, and the first metal layer is a lower metal layer.
In some examples the second metal layer is composed of a metal with a higher Young's modulus than the first metal layer, and the second metal layer is an upper metal layer, and the first metal layer is a lower metal layer.
In some examples the first and second metal layers are composed of Molybdenum, and the third metal layer is composed of Ruthenium.
In some examples the Ruthenium metal layer is an upper metal layer.
In some examples the first and second metal layers comprise an upper and lower metal layer respectively, and the third metal layer is deposited on the upper metal layer. Optionally the metal layer deposited on the upper metal layer is composed from a different material than the upper and lower metal layers. Optionally the third metal layer is composed from the same material as the first and/or second metal layers.
In some examples the piezoelectric layer is 300 nanometers thick.
In some examples the first and second metal layers are each 30 nanometers thick.
In some examples the first, second and third metal layers are each 30 nanometers thick.
In some examples the radius of the membrane may be 400 micrometers.
In some examples the device is a microphone.
In some examples the device is a pressure sensor.
According to some embodiments, a method of manufacturing a piezoelectric microelectromechanical systems device comprises providing a substrate, depositing a first metal layer comprising a first metal, a first piezoelectric layer and a second metal layer on the substrate, the second metal layer comprising a second metal, the first and second metals having different properties to compensate deflection due to thermal stress of any or all of the piezoelectric layer, the first metal layer, and second metal layer, and defining a cavity having at least one cavity wall.
According to some embodiments, a wireless mobile device comprises one or more antennas, a front end system that communicates with the one or more antennas, and one or more piezoelectric microelectromechanical systems microphones, each microphone including a first piezoelectric layer, a first metal layer comprising a first metal, a second metal layer comprising a second metal, the first and second metals having different properties to compensate deflection due to thermal stress of any or all of the piezoelectric layer, the first metal layer, and second metal layer, and a substrate including at least one wall defining a cavity and the at least one wall supporting the layers.
Additional EmbodimentsIn some examples, there is disclosed a system for compensating for thermal stress in piezoelectric microelectromechanical systems devices at least partially spanning a cavity. The system can include at least one piezoelectric layer at least partially spanning a cavity such that it generates electrical signals when external forces cause the piezoelectric layer to vibrate with respect to the cavity. The system can further have at least one electrode layer including a conductive metal positioned adjacent the piezoelectric layer and configured as an electrode to accept the electrical signals. The piezoelectric layer and electrode layer can have an expected thermal stress tending to cause expected deflection even when external forces are not causing the piezoelectric layer to vibrate. The system can further include a compensation layer positioned adjacent at least one of the piezoelectric layer and the at least one electrode layer and configured to counteract the expected deflection from the expected thermal stress.
In some examples, the compensation layer has a selected thickness configured to resist pre-excitation bowing of the piezoelectric layer and the at least one electrode layer.
In some examples, the compensation layer has a selected material property configured to resist pre-excitation bowing of the piezoelectric layer and the at least one electrode layer.
In some examples, the selected material property includes a property related to stiffness or resiliency.
In some examples, the property related to stiffness or resiliency includes a Young's modulus of the compensation layer.
In some examples, the compensation layer is deposited directly on the electrode layer.
In some examples, the compensation layer is deposited on the piezoelectric layer.
In some examples, the system further includes a second piezoelectric layer and a second electrode layer forming a stack with the at least one piezoelectric layer and the at least one electrode layer such that electrode and piezoelectric layers alternate.
In some examples, the second electrode layer is configured to act as the compensation layer.
In some examples, the compensation layer has a thickness and stiffness that collectively compensate for the expected deflection.
A piezoelectric microelectromechanical systems device can include: a layer set sensitive to acoustic vibration, the layers including at least one piezoelectric layer and a two metal electrode layers, the layer set having an expected thermal stress deflection corresponding to a first thermal condition; a cavity having side walls supporting the layer set and providing space for acoustic vibration of the layer set into the cavity; and a compensation layer deposited directly onto one of the two metal electrode layers, the compensation layer having a compensation characteristic configured to compensate for the expected thermal stress deformation, such that the combined layer set and compensation layer do not have the stress deflection under the first thermal condition.
In some examples, the layer set forms an acoustic membrane spanning the cavity, and between the cavity walls and the membrane is located a silicon dioxide layer.
In some examples, the two metal electrode layers include a layer of Molybdenum and the compensation layer includes Ruthenium deposited on the layer of Molybdenum.
In some examples, the compensation layer is selected to additionally compensate for thermal stress by conducting thermal energy from at least one of the two metal electrode layers, thereby raising the net melting point.
In some examples, at least one electrode layer includes ruthenium and the piezoelectric layer is formed thereon from aluminum nitride.
In some examples the compensation layer is composed of the same metal as one or more of the two metal electrode layers.
In some examples the layer set includes two piezoelectric layers and three metal electrode layers arranged in a stack that alternates between metal and piezoelectric material, and the layer set forms a membrane that spans the cavity.
In some examples the two piezoelectric layers have different thicknesses from each other.
In some examples at least one of the three metal electrode layers has a different thickness than at least one of the other two metal electrode layers.
In some examples the piezoelectric layer is more than 250 nanometers thick, at least one of the metal electrode layers is less than 50 nanometers thick, and the width of the cavity is more than 400 micrometers.
In some examples the piezoelectric microelectromechanical systems device is a microphone configured for use in a wireless mobile device. The wireless mobile device can include one or more antennas and a front end system that communicates with the one or more antennas. It can also include one or more piezoelectric microelectromechanical systems devices, each device including layers having properties configured to compensate for deflection due to thermal stress of other layers spanning a cavity.
Further EmbodimentsIn some embodiments, a piezoelectric microelectromechanical systems device comprises a cavity bounded by walls, and an asymmetrical bimorph structure at least partially spanning the cavity and including at least a piezoelectric layer and two electrode layers. The electrode layers can have relative thicknesses configured to compensate for expected temperature stress in the bimorph structure.
In some examples, the bimorph structure includes two piezoelectric layers in a stack with three intervening electrode layers formed from metal.
In some examples, the bimorph structure includes a top metal layer, an upper piezoelectric layer, a middle metal layer, a lower piezoelectric layer, and a bottom metal layer, the metal layers including electrode layers.
In some examples, the lower piezoelectric layer is thicker than the upper piezoelectric layer by an amount configured to offset thermal stress affects that would exist if the two piezoelectric layers had the same thickness.
In some examples, the top metal layer is thicker than the middle and bottom metal layers by an amount configured to offset thermal stress affects that would exist if the two piezoelectric layers had the same thicknesses and the metal layers had the same thicknesses.
In some examples, the bottom metal layer is thicker than the middle and top metal layers, and the lower piezoelectric layer is thicker than the upper piezoelectric layer, each by amounts collectively configured to offset thermal stress affects that would exist if the two piezoelectric layers had the same thicknesses and the three metal layers had the same thicknesses.
In some examples, the piezoelectric microelectromechanical systems device can further include a compensation layer deposited directly on one of the electrode layers and having a thickness configured to further compensate for the expected temperature stress in the bimorph structure.
In some examples, the cavity forms a resonant cavity for an acoustic sensor, the asymmetrical bimorph structure forms a resonator, and the relative thicknesses compensate for expected temperature stress, thereby causing the resonator to respond under expected temperature conditions the same way they are designed to respond without the temperature conditions.
In some examples, the expected temperature stress would cause bowing in one direction and the relative thicknesses cause bowing in an opposite direction, thereby compensating before the temperature stress occurs.
In some embodiments, a piezoelectric microelectromechanical systems device can comprise a layer set sensitive to acoustic vibration, the layers including at least one piezoelectric layer and a two metal electrode layers having the same thickness, the layer set having an expected thermal stress deflection corresponding to a first thermal condition; a cavity having side walls supporting the layer set and providing space for acoustic vibration of the layer set into the cavity; and a compensation layer deposited directly onto one of the two metal electrode layers, the compensation layer having a compensation thicknesses configured to compensate for the expected thermal stress deformation, such that the combined layer set and compensation layer do not have the stress deflection under the first thermal condition.
In some examples, the layer set forms an acoustic membrane spanning the cavity, and between the cavity walls and the membrane is located a silicon dioxide layer.
In some examples, there is disclosed a system for compensating for thermal stress in piezoelectric microelectromechanical systems devices at least partially spanning a cavity. The system can comprise at least one piezoelectric layer at least partially spanning a cavity such that it generates electrical signals when external forces cause the piezoelectric layer to vibrate with respect to the cavity. The system can further comprise at least one electrode layer including a conductive metal positioned adjacent the piezoelectric layer and configured as an electrode to accept the electrical signals. The piezoelectric layer and electrode layer can have an expected thermal stress tending to cause expected deflection even when external forces are not causing the piezoelectric layer to vibrate. The system can further comprise a compensation layer positioned adjacent at least one of the piezoelectric layer and the at least one electrode layer and configured to counteract the expected deflection from the expected thermal stress.
In some examples, the compensation layer has a selected thickness configured to resist pre-excitation bowing of the piezoelectric layer and the at least one electrode layer.
In some examples, the compensation layer has a selected material property configured to resist pre-excitation bowing of the piezoelectric layer and the at least one electrode layer.
In some examples, the selected material property comprises a property related to stiffness or resiliency.
In some examples, the property related to stiffness or resiliency comprises a Young's modulus of the compensation layer.
In some examples, the compensation layer is deposited directly on the electrode layer.
In some examples, the compensation layer is deposited on the piezoelectric layer.
In some examples, the system further comprises a second piezoelectric layer and a second electrode layer forming a stack with the at least one piezoelectric layer and the at least one electrode layer such that electrode and piezoelectric layers alternate.
In some examples, the second electrode layer is configured to act as the compensation layer.
In some examples, the compensation layer has a thickness and stiffness that collectively compensate for the expected deflection.
According to an embodiment there is provided a piezoelectric microelectromechanical systems device, including a first piezoelectric layer, a first metal layer adjacent the first piezoelectric layer and comprising a first metal, a second metal layer comprising a second metal, the first and second metals having different properties to compensate for deflection due to thermal stress of any or all of the piezoelectric layer, the first metal layer, and second metal layer and a substrate including at least one wall defining a cavity and the at least one wall supporting the layers.
In some examples the device includes a third metal layer.
In some examples the first, second and third metal layers are upper, lower and middle layers respectively.
In some examples two of the first, second and third metal layers comprise different thicknesses from each other.
More EmbodimentsIn some examples the third metal layer is composed of a different metal from the first metal layer and the second metal layer.
In some examples the third metal is composed of the same metal of the first metal layer and/or second metal layer.
In some examples the device comprises a second piezoelectric layer adjacent the first or second metal layer and the third metal layer is adjacent the second piezoelectric layer.
In some examples the first and second piezoelectric layers have different thicknesses from each other.
In some examples the piezoelectric layer and first and second metal layers are alternated.
In some examples the first piezoelectric layer, second piezoelectric layer, first metal layer, second metal layer and third metal layer are alternated.
In some examples, the layers are arranged in a stack that alternates between metal and piezoelectric material.
In some examples the piezoelectric and metal layers form a membrane that spans the cavity.
In some examples the piezoelectric and metal layers form a cantilever that extends across at least a portion of the cavity.
In some examples the second metal layer is composed of a metal with a higher Young's modulus than the first metal layer, and the second metal layer is an upper metal layer, and the first metal layer is a lower metal layer.
In some examples the second metal layer is composed of a metal with a higher Young's modulus than the first metal layer, and the second metal layer is an upper metal layer, and the first metal layer is a lower metal layer.
In some examples the first and second metal layers are composed of Molybdenum, and the third metal layer is composed of Ruthenium.
In some examples the Ruthenium metal layer is an upper metal layer.
In some examples the first and second metal layers comprise an upper and lower metal layer respectively, and the third metal layer is deposited on the upper metal layer. Optionally the metal layer deposited on the upper metal layer is composed from a different material than the upper and lower metal layers. Optionally the third metal layer is composed from the same material as the first and/or second metal layers.
In some examples the piezoelectric layer is 300 nanometers thick.
In some examples the first and second metal layers are each 30 nanometers thick.
In some examples the first, second and third metal layers are each 30 nanometers thick.
In some examples the radius of the membrane may be 400 micrometers.
In some examples the device is a microphone.
In some examples the device is a pressure sensor.
According to some embodiments, a method of manufacturing a piezoelectric microelectromechanical systems device comprises providing a substrate, depositing a first metal layer comprising a first metal, a first piezoelectric layer and a second metal layer on the substrate, the second metal layer comprising a second metal, the first and second metals having different properties to compensate deflection due to thermal stress of any or all of the piezoelectric layer, the first metal layer, and second metal layer, and defining a cavity having at least one cavity wall.
According to some embodiments, a wireless mobile device comprises one or more antennas, a front end system that communicates with the one or more antennas, and one or more piezoelectric microelectromechanical systems microphones, each microphone including a first piezoelectric layer, a first metal layer comprising a first metal, a second metal layer comprising a second metal, the first and second metals having different properties to compensate deflection due to thermal stress of any or all of the piezoelectric layer, the first metal layer, and second metal layer, and a substrate including at least one wall defining a cavity and the at least one wall supporting the layers.
Still other aspects, embodiments, and advantages of these exemplary aspects and embodiments are discussed in detail below. Embodiments disclosed herein may be combined with other embodiments in any manner consistent with at least one of the principles disclosed herein, and references to “an embodiment,” “some embodiments,” “an alternate embodiment,” “various embodiments,” “one embodiment” or the like are not necessarily mutually exclusive and are intended to indicate that a particular feature, structure, or characteristic described may be included in at least one embodiment. The appearances of such terms herein are not necessarily all referring to the same embodiment.
Various aspects of at least one embodiment are discussed below with reference to the accompanying figures, which are not intended to be drawn to scale. The figures are included to provide illustration and a further understanding of the various aspects and embodiments and are incorporated in and constitute a part of this specification, but are not intended as a definition of the limits of the invention. In the figures, each identical or nearly identical component that is illustrated in various figures is represented by a like numeral. For purposes of clarity, not every component may be labeled in every figure. In the figures:
Aspects and embodiments described herein are directed to a piezoelectric micromechanical systems (MEMS) device for thermal compensation. Temperature can affect a piezoelectric MEMS device, causing the piezoelectric layers and the metal layers to expand or contract and cause unwanted deflection and residual stress in the membrane or cantilever, reducing the performance of the device. Embodiments described herein are directed at solving this problem.
It is to be appreciated that embodiments of the methods and apparatuses discussed herein are not limited in application to the details of construction and the arrangement of components set forth in the following description or illustrated in the accompanying drawings.
The methods and apparatuses are capable of implementation in other embodiments and of being practiced or of being carried out in various ways. Examples of specific implementations are provided herein for illustrative purposes only and are not intended to be limiting. Also, the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. The use herein of “including,” “comprising,” “having,” “containing,” “involving,” and variations thereof is meant to encompass the items listed thereafter and equivalents thereof as well as additional items. References to “or” may be construed as inclusive so that any terms described using “or” may indicate any of a single, more than one, and all the described terms.
The embodiments described herein are directed to a piezoelectric MEMS device comprising a membrane. However, the techniques described herein may be applied to a cantilever sensor in a device. The device described herein may be a microphone or a pressure sensor, or any other piezoelectric MEMS device. As an example, embodiments described herein are directed to microphones, however it will be appreciated that the techniques and methods described herein are applicable for other devices.
In an embodiment comprising a cantilever, there may also be at least one piezoelectric layer, and at least two metal layers arranged with generally the same shape around the piezoelectric layer to collectively form one or more cantilevered beams. A cantilever embodiment can be similar to the illustrated portion shown in
In the described embodiments, the piezoelectric layers may be 300 nanometers thick, the metal layers, i.e. electrodes, may be 30 nanometers thick, the silicon dioxide may be 3 micrometers thick in the radial direction, and the radius of the membrane may be 400 micrometers. The membrane is supported by the cavity walls, wherein the cavity walls are composed of a silicon dioxide layer 1011 located on top of silicon. Thus there may be an overlap between the silicon dioxide and membrane (e.g., at the anchor region 113) of around 2 to 3 micrometers.
Although not shown, different thicknesses of layers may also be used to compensate for a differences in thermal coefficient of expansion between layered materials. For example, in an arrangement in which the metal layer layers have a lower thermal coefficient of expansion than the piezoelectric layers, thicker metal layers may be used so that the difference in thermal coefficient of expansion may be compensated or offset at least to some degree.
In some embodiments of the illustrated device, the piezoelectric layer 603 is 300 nanometers thick, the metal layers, i.e. electrodes 607, are 30 nanometers thick, the silicon dioxide 611 is 3 micrometers thick, and the radius of the membrane is 400 micrometers. The membrane is supported by the silicon dioxide walls, and thus there is an overlap (see the anchor region 113 of
There are embodiments using other combinations of material, which have similar Young's moduli and thermal coefficients of expansion which have not been described here. Furthermore, different combinations of metal layers may be used to compensate each other, wherein one of the three metal layers is a different material than the other two. Varying the embodiment of that in
As described in
Although it may be possible to compensate the stress and deflection of the device by varying the thickness of the piezoelectric layers and/or metal layers, this may affect the performance of the microphone. In a piezoelectric MEMS device, charge is generated due to an external sound pressure and the resultant membrane deflection. However, when the external sound is constant, the sensor deflection depends on compliance of the sensor, or the thickness of the layer and its stiffness (e.g., Young's modulus). Therefore, properties and dimensions of the layers in the microphone may affect the device's performance. In a microphone in which the piezoelectric layer is too thick, this results in a low compliance and therefore a low deflection which results in a low output. In a microphone in which the metal is too thick, there is also a low output, since the metal layers can change the net stiffness of the device (for similar reasons as the too thick piezoelectric layer). In a microphone in which very thin metal and piezoelectric layers are used, there may be too high a compliance, resulting in a stack which easily breaks, has a low resonant frequency in the acoustic range, and therefore may not be a good sensor. Therefore, the stack can be optimized or improved by taking into account the above and the necessary parameters of a sensor. Thinner electrodes may be preferable as they increase compliance and reduce stiffness. Furthermore, when the thickness of piezoelectric layers is changed, the stress is changed, and consequently the charge is changed, and so the electrode structure, e.g., metal layers, may need to be reconfigured or re-optimized. This re-optimization of metal layers may be especially helpful as the change in charge may result in an electrode from a positive section overlapping a piezoelectric area that produces negative charge distribution. This results in a reduced output signal, which can result in a zero output. Therefore, when altering the thickness of the piezoelectric layers to optimize the deflection, it may be preferable to use this technique to fine tune the results, and not vary the thickness by large enough amounts to affect the performance of the microphone due to charge generation.
A change in metal layer thickness may also affect the performance of the microphone. An increase in thickness of a metal layer may increase the mass loading effect. An increased thickness may also reduce the resonant frequency of the sensor. This is not preferable for most microphones, which are generally required to have a high resonant frequency for higher acoustic range. However, this may not be a problem when altering the thickness a small amount to fine tune the deflection and stress.
However, in an embodiment having only two metal layers, the opportunities to compensate the stress and deflection are less than in an embodiment with three metal layers, although residual stress control and prediction of compensation are simpler for smaller numbers of layers in the stack. Therefore, in some embodiments, as shown in the cross-sectional view of
Further to the advantages of the methods and devices described above, enhancement and/or optimization of a device by using different materials of metal layers can also improve the quality of the membrane formed. In the use of materials, such as aluminum nitride, there are considerations which may be taken into account when forming the device, such as the grain size and direction of growth of the layer of the aluminum nitride. Due to this, the quality of the aluminum nitride layer is dependent on the substrate, or support material. Using the methods and techniques described herein, it is possible to optimize the membrane and thus performance of the microphone by choosing materials which provide the best results when used together. For example, aluminum nitride and ruthenium both have hexagonal crystal structures, and therefore, using the techniques described herein, it is possible to deposit the aluminum nitride on a ruthenium layer, resulting in a better device. Considering different physical properties of materials used for the piezoelectric layers and metal layer layers, the combined structure can enhance or optimize the device.
The techniques described here are also applicable to any number of layers, so that the device is not limited to two piezoelectric layers and three metal layers. Instead, these techniques may be applied to other layered devices.
It will be noted that
The microphone according to embodiments described herein may be manufactured according to the method whose steps are shown in
In embodiments in which the membrane comprises a hole extending through all of the layers of the membrane, through which air can pass from one side of the membrane to the other, this may be etched in an additional step between the steps described in
The transceiver 1503 aids in conditioning signals transmitted to and/or received from the antennas 1504.
The antennas 1504 can include antennas used for a wide variety of types of communications. For example, the antennas 1504 can include antennas 1504 for transmitting and/or receiving signals associated with a wide variety of frequencies and communications standards.
The baseband system 1501 is coupled to the user interface to facilitate processing of various user input and output, such as voice and data. The baseband system 1501 provides the transceiver 1502 with digital representations of transmit signals, which the transceiver 1502 processes to generate RF signals for transmission. The baseband system 1501 also processes digital representations of received signals provided by the transceiver 1502. As shown in
The memory can be used for a wide variety of purposes, such as storing data and/or instructions to facilitate the operation of the wireless device and/or to provide storage of user information.
The power management system 1505 provides a number of power management functions of the wireless device.
The power management system 1505 receives a battery voltage from the battery 1508. The battery 1508 can be any suitable battery for use in the wireless device, including, for example, a lithium-ion battery.
Having described above several aspects of at least one embodiment, it is to be appreciated various alterations, modifications, and improvements will readily occur to those skilled in the art. Such alterations, modifications, and improvements are intended to be part of this disclosure and are intended to be within the scope of the invention. Accordingly, the foregoing description and drawings are by way of example only, and the scope of the invention should be determined from proper construction of the appended claims, and their equivalents.
For the purpose of description, it will be understood that a module can be a physical module and/or a functional block configured to provide a desired modular functionality with one or more devices and/or circuits. For example, a physical module can be a packaged module implemented on a packaging substrate, a packaged die configured to be mounted on a circuit board, or any other physical device configured to provide RF functionality. It will also be understood that a module can include one or more physical devices, including a plurality of physical devices with each sometimes being referred to as a module itself.
Also for the purpose of description, it will be understood that a component can be physical device and/or an assembly of one or more devices and/or circuits configured to provide a functionality. In some situations, a component can also be referred to as a module, and vice versa.
The present disclosure describes various features, no single one of which is solely responsible for the benefits described herein. It will be understood that various features described herein may be combined, modified, or omitted, as would be apparent to one of ordinary skill. Other combinations and sub-combinations than those specifically described herein will be apparent to one of ordinary skill, and are intended to form a part of this disclosure.
Unless the context clearly requires otherwise, throughout the description and the claims, the words “comprise,” “comprising,” and the like are to be construed in an inclusive sense, as opposed to an exclusive or exhaustive sense; that is to say, in the sense of “including, but not limited to.” The word “coupled”, as generally used herein, refers to two or more elements that may be either directly connected, or connected by way of one or more intermediate elements. Additionally, the words “herein,” “above,” “below,” and words of similar import, when used in this application, shall refer to this application as a whole and not to any particular portions of this application. Where the context permits, words in the above Detailed Description using the singular or plural number may also include the plural or singular number respectively. The word “or” in reference to a list of two or more items, that word covers all of the following interpretations of the word: any of the items in the list, all of the items in the list, and any combination of the items in the list. The word “exemplary” is used exclusively herein to mean “serving as an example, instance, or illustration.” Any implementation described herein as “exemplary” is not necessarily to be construed as preferred or advantageous over other implementations.
The disclosure is not intended to be limited to the implementations shown herein. Various modifications to the implementations described in this disclosure may be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other implementations without departing from the spirit or scope of this disclosure. The teachings of the invention provided herein can be applied to other methods and systems, and are not limited to the methods and systems described above, and elements and acts of the various embodiments described above can be combined to provide further embodiments. Accordingly, the novel methods and systems described herein may be embodied in a variety of other forms; furthermore, various omissions, substitutions and changes in the form of the methods and systems described herein may be made without departing from the spirit of the disclosure. The accompanying claims and their equivalents are intended to cover such forms or modifications as would fall within the scope and spirit of the disclosure.
Claims
1. A piezoelectric microelectromechanical systems device, comprising:
- a first piezoelectric layer;
- a first metal layer adjacent the first piezoelectric layer and including a first metal;
- a second metal layer including a second metal, the first and second metals having different properties to compensate for deflection due to thermal stress of any or all of the piezoelectric layer, the first metal layer, and second metal layer; and
- a substrate including at least one wall defining a cavity and the at least one wall supporting the layers.
2. The piezoelectric microelectromechanical systems device of claim 1 wherein the device includes a third metal layer.
3. The piezoelectric microelectromechanical systems device of claim 2 wherein the first, second and third metal layers are upper, lower and middle layers respectively.
4. The piezoelectric microelectromechanical systems device of claim 2 wherein the third metal layer is composed of a different metal from the first metal layer and the second metal layer.
5. The piezoelectric microelectromechanical systems device of claim 2 wherein the third metal is composed of the same metal of the first metal layer and/or second metal layer.
6. The piezoelectric microelectromechanical systems device of claim 1 wherein the device includes a second piezoelectric layer adjacent the first or second metal layer and the third metal layer is adjacent the second piezoelectric layer.
7. The piezoelectric microelectromechanical systems device of claim 2 wherein the layers are arranged in a stack that alternates between metal and piezoelectric material.
8. The piezoelectric microelectromechanical systems device of claim 1 wherein the piezoelectric and metal layers form a membrane that spans the cavity.
9. The piezoelectric microelectromechanical systems device of claim 1 wherein the piezoelectric and metal layers form a cantilever that extends across at least a portion of the cavity.
10. The piezoelectric microelectromechanical systems device of claim 1 wherein the second metal layer is composed of a metal with a higher Young's modulus than the first metal layer, and the second metal layer is an upper metal layer, and the first metal layer is a lower metal layer.
11. The piezoelectric microelectromechanical systems device of claim 2 wherein the second metal layer is composed of a metal with a higher Young's modulus than the first metal layer, and the second metal layer is an upper metal layer, and the first metal layer is a lower metal layer.
12. The piezoelectric microelectromechanical systems device of claim 2 wherein the first and second metal layers are composed of Molybdenum, and the third metal layer is composed of Ruthenium.
13. The piezoelectric microelectromechanical systems device of claim 12 wherein the Ruthenium metal layer is an upper metal layer.
14. The piezoelectric microelectromechanical systems device of claim 2 wherein the first and second metal layers include an upper and lower metal layer respectively, and the third metal layer is deposited on the upper metal layer.
15. The piezoelectric microelectromechanical systems device of claim 14 wherein the metal layer deposited on the upper metal layer is composed of a different material than the upper and lower metal layers.
16. The piezoelectric microelectromechanical systems device of claim 14 wherein the third metal layer is composed from the same material as the first and/or second metal layers.
17. The piezoelectric microelectromechanical systems device of claim 1 wherein the piezoelectric layer is 300 nanometers thick and the first and second metal layers are each 30 nanometers thick.
18. The piezoelectric microelectromechanical systems device of claim 2 wherein the first, second and third metal layers are each 30 nanometers thick.
19. The piezoelectric microelectromechanical systems device of claim 8 wherein the radius of the membrane is at least 400 micrometers.
20. The piezoelectric microelectromechanical systems device of claim 1 wherein the device is a microphone.
21. The piezoelectric microelectromechanical systems device of claim 1 wherein the device is a pressure sensor.
22. A method of manufacturing a piezoelectric microelectromechanical systems device, the method comprising:
- providing a substrate;
- depositing a first metal layer including a first metal, a first piezoelectric layer and a second metal layer on the substrate, the second metal layer including a second metal, the first and second metals having different properties to compensate deflection due to thermal stress of any or all of the piezoelectric layer, the first metal layer, and second metal layer; and
- defining a cavity having at least one cavity wall.
23. A wireless mobile device comprising:
- one or more antennas;
- a front end system that communicates with the one or more antennas; and
- one or more piezoelectric microelectromechanical systems devices, each device including a first piezoelectric layer, a first metal layer including a first metal, and a second metal layer including a second metal, the first and second metals having different properties to compensate for deflection due to thermal stress of any or all of the piezoelectric layer, the first metal layer, and second metal layer, and each device further including a substrate including at least one wall defining a cavity, the at least one wall supporting the layers.
Type: Application
Filed: Sep 28, 2022
Publication Date: Mar 30, 2023
Inventors: Siarhei Dmitrievich Barsukou (Takarazuka-Shi), Myeong Gweon Gu (Seoul), Hiroyuki Nakamura (Osaka-fu)
Application Number: 17/936,350