Abstract: A method for fabricating a resonator, and in particular, a thin film bulk acoustic resonator (FBAR), and a resonator embodying the method are disclosed. An FBAR is fabricating on a substrate by introducing a mass loading electrode to a bottom electrode layer. For a substrate having multiple resonators, mass loading bottom electrode is introduced for only selected resonator to provide resonators having different resonance frequencies on the same substrate.

Abstract: A method for fabricating a resonator, and in particular, a thin film bulk acoustic resonator (FBAR), and a resonator embodying the method are disclosed. A resonator is fabricated on a substrate, and its top electrode 56 is oxidized to form a oxide layer 58. For a substrate having multiple resonators, the top electrode 56 of only selected resonator is oxidized to provide resonators having different resonance frequencies on the same substrate.

Abstract: A filter, such as a transmit filter of a duplexer, includes an array of acoustic resonators that cooperate to establish an asymmetrically shaped filter response over a target frequency passband. The acoustic resonators are preferably film bulk acoustic resonators (FBARs). The filter response defines an insertion loss profile in which a minimum insertion loss within the target passband is located at or near a first end of the frequency passband, while the maximum insertion loss is located at or near the opposite end of the frequency passband. In the transmit filter embodiment, the minimum insertion loss is at or near the high frequency end of the filter response, which is tailored by selectively locating poles and zeros of the array of FBARs.

Abstract: A microcap wafer-level package is provided in which a micro device is connected to bonding pads on a base wafer. A peripheral pad on the base wafer encompasses the bonding pads and the micro device. A cap wafer has gaskets formed thereon using a thick photoresist semiconductor photolithographic process. Bonding pad gaskets match the perimeters of the bonding pads and a peripheral pad gasket matches the peripheral pad on the base wafer. Wells are located inside the perimeters of the bond pad gaskets and are formed to a predetermined depth in the cap wafer. The cap wafer is then placed over the base wafer to cold weld bond the gaskets to the pads and form a hermetically sealed volume between the bonding pad gaskets and the peripheral pad gasket. The cap wafer is then thinned below the predetermined depth until the wells become through holes that provide access to the bonding pads inside the package, but outside the hermetically sealed volume, for connecting wires from a micro device utilizing system.

Abstract: A bulk acoustic resonator having a high quality factor is formed on a substrate having a depression formed in a top surface of the substrate. The resonator includes a first electrode, a piezoelectric material and a second electrode. The first electrode is disposed on the top surface of the substrate and extends beyond the edges of the depression by a first distance to define a first region therebetween. The piezoelectric material is disposed on the top surface of the substrate and over the first electrode, and the second electrode is disposed on the piezoelectric material. The second electrode includes a portion that is located above the depression. The portion of the second electrode that is located over the depression has at least one edge that is offset from a corresponding edge of the depression by a second distance to define a second region therebetween. The first and second regions have different impedances, as a result of the different materials located in the two regions.

Abstract: A bulk acoustic resonator having a high quality factor is formed on a substrate having a depression formed in a top surface of the substrate. The resonator includes a first electrode, a piezoelectric material and a second electrode. The first electrode is disposed on the top surface of the substrate and extends beyond the edges of the depression by a first distance to define a first region therebetween. The piezoelectric material is disposed on the top surface of the substrate and over the first electrode, and the second electrode is disposed on the piezoelectric material. The second electrode includes a portion that is located above the depression. The portion of the second electrode that is located over the depression has at least one edge that is offset from a corresponding edge of the depression by a second distance to define a second region therebetween. The first and second regions have different impedances, as a result of the different materials located in the two regions.

Abstract: A device includes a die that contains a filter circuit. The filter is implemented using film bulk acoustic resonators. A package contains the die. The package includes a base portion. Signal paths are incorporated in the base portion. Solder joints attach the die to the base portion. The solder joints electrically connect pads on the die to the signal paths in the base portion. The solder joints do not include, and are used instead of, wire bonds.

Abstract: A filter formed of acoustic resonators, where each resonator has its own cavity and a bottom electrode that spans the entirety of the cavity, so that the bottom electrode has an unsupported interior region surrounded by supported peripheral regions. In the preferred embodiment, the cavity is formed by etching a depression into the substrate, filling the depression with a sacrificial material, depositing the piezoelectric and electrode layers that define an FBAR or SBAR, and then removing the sacrificial material from the depression. Also in the preferred embodiment, the sacrificial material is removed via release holes that are limited to the periphery of the depression. Preferably, the bottom electrode is the only electrode that spans the cavity, thereby limiting the formation of parasitic FBARs or SBARs. In one embodiment, the bottom electrode includes a serpentine edge that leaves a portion of one side of the cavity free of overlap by the bottom electrode, so that a top electrode may overlap this portion.

Abstract: A plurality of acoustic resonators are manufactured in a batch process by forming cavities in a substrate and filling the cavities with a sacrificial layer. An FBAR membrane comprising a bottom electrode, a piezoelectric layer, and a top electrode is formed over each cavity and the sacrificial layer. The substrate is then thinned and the substrate is separated into a plurality of dice using a scribe and break process. The sacrificial layer is then removed and the FBAR filter is mounted in a package with thermal vias being thermal communication with underside of the FBAR filter. The production method improves thermal properties by increasing the efficiency of heat dissipation from the FBAR filter. In addition, electromagnetic interference is decreased by reducing the distance between a primary current flowing over the surface of the FBAR filter and an image current flowing in a ground plane beneath the FBAR filter.

Abstract: A microcap wafer-level package is provided in which a micro device is connected to bonding pads on a base wafer. A peripheral pad on the base wafer encompasses the bonding pads and the micro device. A cap wafer has gaskets formed thereon using a thick photoresist semiconductor photolithographic process. Bonding pad gaskets match the perimeters of the bonding pads and a peripheral pad gasket matches the peripheral pad on the base wafer. Wells are located inside the perimeters of the bond pad gaskets and are formed to a predetermined depth in the cap wafer. The cap wafer is then placed over the base wafer to cold weld bond the gaskets to the pads and form a hermetically sealed volume between the bonding pad gaskets and the peripheral pad gasket. The cap wafer is then thinned below the predetermined depth until the wells become through holes that provide access to the bonding pads inside the package, but outside the hermetically sealed volume, for connecting wires from a micro device utilizing system.

Abstract: A microcap wafer-level package is provided in which a micro device is connected to bonding pads on a base wafer. A peripheral pad on the base wafer encompasses the bonding pads and the micro device. A cap wafer has gaskets formed thereon using a thick photoresist semiconductor photolithographic process. Bonding pad gaskets match the perimeters of the bonding pads and a peripheral pad gasket matches the peripheral pad on the base wafer. Wells are located inside the perimeters of the bond pad gaskets and are formed to a predetermined depth in the cap wafer. The cap wafer is then placed over the base wafer to cold weld bond the gaskets to the pads and form a hermetically sealed volume between the bonding pad gaskets and the peripheral pad gasket. The cap wafer is then thinned below the predetermined depth until the wells become through holes that provide access to the bonding pads inside the package, but outside the hermetically sealed volume, for connecting wires from a micro device utilizing system.

Abstract: A microcap wafer-level package is provided in which a micro device is connected to bonding pads on a base wafer. A peripheral pad on the base wafer encompasses the bonding pads and the micro device. A cap wafer has gaskets formed thereon using a thick photoresist, semiconductor photolithographic process. Bonding pad gaskets match the perimeters of the bonding pads and a peripheral pad gasket matches the peripheral pad on the base wafer. Wells are located inside the perimeters of the bond pad gaskets and are formed to a predetermined depth in the cap wafer. The cap wafer is then placed over the base wafer to cold weld bond the gaskets to the pads and form a hermetically sealed volume between the bonding pad gaskets and the peripheral pad gasket. The cap wafer is then thinned below the predetermined depth until the wells become through holes that provide access to the bonding pads inside the package, but outside the hermetically sealed volume, for connecting wires from a micro device utilizing system.

Abstract: An FBAR-based duplexer that comprises a first port, a second port, a third port, a first band-pass filter connected between the first port and the third port and a series circuit connected between the second port and the third port. The first band-pass filter includes a first ladder circuit having shunt and series elements. Each of the elements of the first ladder circuit comprises a film bulk acoustic resonator (FBAR). The series circuit includes a 90° phase shifter in series with a second band-pass filter. The second band-pass filter includes a second ladder circuit having shunt and series elements. Each of the elements of the second ladder circuit comprises a film bulk acoustic resonator. A band-pass filter comprising shunt elements and series elements in which the series elements and the shunt elements are connected to form a ladder circuit, and each of the elements includes a film bulk acoustic resonator (FBAR).

Abstract: A microcap wafer-level package is provided in which a micro device is connected to bonding pads on a base wafer. A peripheral pad on the base wafer encompasses the bonding pads and the micro device. A cap wafer is processed to form wells of a predetermined depth in the cap wafer. A conductive material is made integral with the walls of the wells in the cap wafer. The cap wafer has contacts and a peripheral gasket formed thereon where the contacts are capable of being aligned with the bonding pads on the base wafer, and the gasket matches the peripheral pad on the base wafer. The cap wafer is then placed over the base wafer so as to bond the contact and gasket to the pads and form a hermetically sealed volume within the peripheral gasket. The cap wafer is thinned to form a “microcap”. The microcap is thinned below the predetermined depth until the semiconductor dopant is exposed to become conductive vias through the cap wafer to outside the hermetically sealed volume.

Abstract: A bulk acoustic wave device that provides a high spectral purity, high Q, resonator in the radio frequency and microwave frequency ranges. Such resonators may be coupled together to form filters or other frequency selective devices. The bulk acoustical wave filter is constructed from a piezoelectric (PZ) material having a first surface and a second surface and first and second electrodes. The first electrode includes an electrically conducting layer on the first surface, and the second electrode includes an electrically conducting layer on the second surface. The first electrode overlies at least a portion of the second electrode, the portion of the first electrode that overlies the second electrode has a periphery which is a non-rectangular, irregular polygon. In the preferred embodiment of the present invention, the periphery is a three-sided, four-sided, or n-sided irregular polygon in which no two sides are parallel to one another.

Abstract: An acoustical resonator and a method for making the same. A resonator according to the present invention includes a layer of piezoelectric material sandwiched between first and second electrodes. The first electrode includes a conducting sheet having a RMS variation in height of less than 2 .mu.m. The resonator bridges a cavity in a substrate on which the resonator is constructed. The resonator is constructed by creating a cavity in the substrate and filling the same with a sacrificial material that can be rapidly removed from the cavity after the deposition of the various layers making up the resonator. The surface of the filled cavity is polished to provide a RMS variation in height of less than 0.5 .mu.m. The first electrode is deposited on the polished surface to a thickness that assures that the RMS variation in height of the metallic layer is less than 2 .mu.m. The piezoelectric layer is deposited on the first electrode and the second electrode is then deposited on the piezoelectric layer.

Abstract: An RF tag having an antenna for receiving a RF signal having a frequency band between first and second frequencies and an acoustical resonator having a resonant frequency related to the first and second frequencies. The acoustical resonator has first and second electrodes that sandwich a layer of piezoelectric material. The antenna is connected to one of these electrodes. The resonator filters the signal received on the antenna. The filter can function either as a notch filter or as a bandpass filter. A resonator that acts as a bandpass filter includes a third electrode and a second layer piezoelectric material sandwiched between the second electrode and the third electrode. A frequency multiplier circuit may be incorporated in the RF tag to provide a response signal that occupies a frequency band at a frequency above the second frequency. In one embodiment of the present invention, multiple resonators having different resonant frequencies are utilized to generate a response code.

Abstract: An acoustical resonator comprising top and bottom electrodes that sandwich a PZ layer. The resonance frequency of the acoustical resonator may be adjusted after fabrication by utilizing heating elements included in the acoustical resonator and/or by adjusting the thickness of a tuning layer. In the preferred embodiment of the present invention, the electrodes comprise Mo layers. One embodiment of the present invention is constructed on a Si.sub.3 N.sub.4 membrane. A second embodiment of the present invention is constructed such that it is suspended over a substrate on metallic columns. In the preferred embodiment of the present invention, the electrodes are deposited by a method that minimizes the stress in the electrodes.

Abstract: A system is described that tunes the resonance frequency of a thin film acoustic resonator to a desired frequency after the resonator is fabricated. The resonator has a metal layer in an acoustic path of the resonator. The system includes a substantial vacuum reaction chamber within which the resonator is located. A heater is provided that heats the metal layer to an elevated temperature to either grow or etch the metal layer depending on a reaction gas introduced into the reaction chamber. A control circuit is also provided that controls the heater to heat the metal layer such that the thickness of the metal layer is adjusted to obtain the desired frequency after fabrication of the resonator. Methods of tuning the resonance frequency of the acoustic resonator to the desired frequency are also described.

Abstract: An acoustical resonator comprising top and bottom electrodes that sandwich a PZ layer. The resonance frequency of the acoustical resonator may be adjusted after fabrication by utilizing heating elements included in the acoustical resonator and/or by adjusting the thickness of a tuning layer. In the preferred embodiment of the present invention, the electrodes comprise Mo layers. One embodiment of the present invention is constructed on a Si.sub.3 N.sub.4 membrane. A second embodiment of the present invention is constructed such that it is suspended over a substrate on metallic columns. In the preferred embodiment of the present invention, the electrodes are deposited by a method that minimizes the stress in the electrodes.