Nokia Mobile Phones Limited

Nokia Corporation

Juha Ell&auml;

Jyrki Kaitila

Pasi Tikka

Helena Pohjonen

Markku Antero Ylilammi

Robert Aigner

Meeri Talvikki Partanen

A resonator structure ( ), where a certain wave mode is piezoelectrically excitable, comprises at least two conductor layers ( ) and at least one piezoelectric layer ( ) in between the conductor layers, said conductor layers and piezoelectric layer extending over a first area of the resonator structure, which first area is a piezoelectrically excitable area of the resonator structure. The resonator structure is characterized in that it comprises a frame-like zone ( ) confining a center area ( ) within the first area, a cut-off frequency of the piezoelectrically excited wave mode in the layer structure of the frame-like zone is different from that in the layer structure of the center area, and width of the frame-like zone and acoustical properties of the layer structure in the frame-like zone are arranged so that displacement relating to the piezoelectrically excited strongest resonance mode is substantially uniform in the center area of the resonator.

Resonator structure and a filter comprising such a resonator structure

Resonator structure ( ) comprises two conductor layers ( ) and a piezoelectric layer ( ) in between the conductor layers, and said conductor layers and piezoelectric layer extend over a first area of the resonator structure, which first area is a piezoelectrically excitable area of the resonator structure. The resonator structure is characterized in that it is arranged to have a zone ( ), which confines a center area ( ) within the first area of the resonator, and the layer structure in the zone is arranged to be such that piezoelectrically excited vibrations are dampened more effectively in the zone than in the center area.

Resonator structure having a dampening material and a filter having such a resonator structure

A function-oriented manufacturing approach in RF front-end architecture for use in a multi-band mobile phone. Electronic components in a front-end module, such as low-noise amplifiers that require the demanding silicon bipolar process, are fabricated separately from those components in an RF-ASIC that require the less demanding, yet more costly, Bi-CMOS process. When the transmission frequency band and the receiving band overlap, separate receiving antenna and transmitting antenna are used, instead of an antenna switch module with a duplexer, connected to separate bandpass filters for band selection. Differential Rx antennas are used so that the whole Rx-chain can be made differential. Furthermore, different impedances for Tx out and Rx in can be realized.

Versatile RF front-end multiband mobile terminals

A filter structure ( ) comprises a first piezoelectric resonator ( ), whose resonance frequency is a first resonance frequency and which is connected to an input conductor ( ). In order to increase the power handling capacity of the filter structure, it comprises other piezoelectric resonators connected in series with the first piezoelectric resonator. In this plurality ( ) of piezoelectric resonators, each resonator has a resonance frequency substantially equal to the first resonance frequency. The plurality ( ) of piezoelectric resonators is connected to the rest of the filter structure only through the first piezoelectric resonator ( ) at one end of said plurality and through a second piezoelectric resonator ( ), which is at the other end said plurality. The impedance of said plurality is arranged to match the impedance level of the filter structure. An arrangement for transmitting and for transmitting and receiving radio frequency signal is also described.

Filter structure and arrangement comprising piezoelectric resonators

A filter structure ( ) comprises a filter section ( ) having at least two branches ( ) connected in parallel. A first branch ( ) of said at least two branches comprises a first plurality ( ) of piezoelectric resonators connected in series, and a second branch ( ) of said at least two branches comprises a second plurality ( ) of piezoelectric resonators and phase shifting means ( ) connected in series. The phase shifting means are arranged to provide a phase shift of substantially 180 degrees.

Filter structure comprising piezoelectric resonators

A bulk acoustic wave device having two resonators in a stacked-up configuration separated by a dielectric layer. The device can be coupled to a lattice filter or a ladder filter to form a passband filter with an unbalanced input port and two balanced output ports. One or more such passband filters can be used, together with another lattice or ladder filter, to form a duplexer having an unbalanced antenna port, two balanced ports for one transceiver part and two balanced ports for another transceiver part.

Bulk acoustic wave resonator with two piezoelectric layers as balun in filters and duplexers

A method of producing a BAW device with reduced spurious resonance, wherein the device comprises a top electrode, a bottom electrode and a piezoelectric layer therebetween. A frame-like structure is formed on top of the top electrode for suppressing the spurious resonances. The frame-like structure is produced in a self-aligning fashion in that the frame-like structure is used to define the top electrode area. Furthermore, it is preferred that the frame-like structure is made of a different material from the top electrode. The frame-like structure is caused to fuse with the contacting part of the top electrode to form an alloy. An etching mask is then used to cover at least part of the frame-like structure and the entire top electrode surrounded by the frame-like structure for etching. An etching medium is used to remove the unreacted portion of the top electrode outside the frame-like structure.

Method of producing thin-film bulk acoustic wave devices

A method of fabricating a plurality of bulk acoustic wave (BAW) resonators on a single substrate, and the corresponding product, the BAW resonators having substantially different resonant frequencies, the method including the steps of: providing a substrate having an upper facing surface; depositing an isolation structure on the upper facing surface of the substrate; depositing a first metallic layer on the isolation structure, the first metallic layer serving as a bottom electrode; and depositing piezolayer material on the bottom electrode so as to have thicknesses corresponding to each of the different resonant frequencies, each different thickness located in a location where a resonator having a resonant frequency corresponding to the thickness is to be located. In one of several embodiments, the step of depositing piezolayer material on the bottom electrode itself includes the steps of: depositing piezolayer material to a thickness corresponding to the lowest frequency resonator; providing hard mask material over areas where the lowest frequency resonators are to be located; and removing the piezolayer material down to the thickness of the next higher frequency resonators. In some applications of the method, the isolation structure is an acoustic mirror, and the method further includes the step of providing the acoustic mirror, interposed between the substrate and the bottom electrode, according to a design that imparts to the acoustic mirror a desired reflection coefficient over a predetermined range of frequency including the substantially different resonant frequencies.

BAW filters having different center frequencies on a single substrate and a method for providing same

A method of fabricating a bulk acoustic wave (BAW) resonator and a BAW resonator so fabricated, the method including the steps of: providing a substrate; providing a first isolation structure; and providing a resonator section including a piezolayer; wherein the first isolation structure includes an acoustic mirror made from only electrically conductive layers of alternating high and low acoustic impedance. In some applications, the first isolation structure is situated between the resonator section and the substrate, while in other applications, the first isolation structure is situated above the resonator section (on the side of the resonator section facing away from the substrate), so that the resonator section lies between the first isolation structure and the substrate, and the resonator then further comprises a second isolation structure situated between the resonator section and the substrate.

Bulk acoustic wave resonator with a conductive mirror

A method of fabricating a multi-resonator bulk acoustic wave (BAW) filter and a filter provided by such a method, the filter having a plurality of layers of materials serving as an acoustic mirror for a plurality of resonator sections, each resonator section including at least a top electrode and a bottom electrode sandwiching a piezolayer, the method including the steps of: choosing dielectric materials for some of the layers of materials serving as the acoustic mirror and metallic materials for the others of the layers; and providing at least one of the metallic layers via a fabrication procedure in which the metallic layer is patterned into distinct portions by an etching process that removes enough of the metallic layer between where different resonator sections are to be placed as to provide electrical isolation between the portions of the layer beneath the different resonator sections; thereby providing a multi-resonator BAW filter with reduced capacitive coupling between resonators, compared to the capacitive coupling present in a multi-resonator BAW filter fashioned in a similar manner except excluding the step of etching to pattern any metallic layers of the similarly fashioned acoustic mirror.

Solidly mounted multi-resonator bulk acoustic wave filter with a patterned acoustic mirror

A method and system for tuning a bulk acoustic wave device at wafer level by reducing the thickness non-uniformity of the topmost surface of the device using a chemical vapor deposition process. A light beam is used to enhance the deposition of material on the topmost surface at one local location at a time. Alternatively, an electrode is used to produce plasma for locally enhancing the vapor deposition process. A moving mechanism is used to move the light beam or the electrode to different locations for reducing the thickness non-uniformity until the resonance frequency of the device falls within specification.

Method and system for wafer-level tuning of bulk acoustic wave resonators and filters by reducing thickness non-uniformity

A method and system for tuning a bulk acoustic wave device at wafer level, wherein the thickness of topmost layer of the device is non-uniform. The thickness non-uniformity causes the resonant frequency of the device to vary from one location to another location of the topmost layer. A laser beam, operatively connected to a beam moving mechanism, is used to locally trim the topmost layer, one location at a time.

Method and system for wafer-level tuning of bulk acoustic wave resonators and filters

A method and system for tuning a bulk acoustic wave device at the wafer level by adjusting the device thickness. In particular, the device thickness has a non-uniformity profile across the device surface. A mask with an aperture is placed over the device surface and a particle beam is applied over the mask to allow part of the particle beam to make contact with the device surface at a localized area beneath the aperture. The particles that pass through the aperture are deposited on the device surface to add material on the device surface, thereby increasing the surface thickness to correct for thickness non-uniformity. Alternatively, the particles that pass through the aperture remove part of the device surface in an etching process, thereby reducing the surface thickness. Prior to thickness adjustment, a frequency measurement device or thickness measurement device is used to map the device surface for obtaining the non-uniformity profile.

A method and system for tuning a bulk acoustic wave device at the wafer level by adjusting the thickness of the device. In particular, the thickness of the device has a non-uniformity profile across the device surface. A mask having a thickness non-uniformity profile based partly on the thickness non-uniformity profile of the device surface is provided on the device surface for etching. A dry etching method is used to remove part of the mask to expose the underlying device surface and further removed the exposed device surface until the thickness non-uniformity of the device surface falls within tolerance of the device.

A monolithic bulk acoustic wave (BAW) duplexer, and a method for fabricating same, the duplexer having a, transmitter section as a first component filter and a receiver section as a second component filter, both component filters fabricated on a single substrate and both including at least one shunt BAW resonator and one series BAW resonator, each BAW resonator including a resonator section atop an isolation structure provided so as to separate the resonator section from the substrate, including: a patterned bottom electrode material for use as the bottom electrode of each of the resonators of the duplexer; a patterned piezoelectric material for use as the piezolayer of each of the resonators of the duplexer; a patterned top electrode material for use as the top electrode of each of the resonators of the duplexer; a tuning layer for the shunt resonator of each of the two component duplexer filters; and a tuning layer for both the series and shunt resonators of one of the two component duplexer filters. In some applications, each isolation structure is an acoustic mirror. Also in some applications, the duplexer further includes at least one planar spiral inductor provided in the course of depositing one or another layer of material in building up the duplexer, the planar spiral inductor having coils spiraling outward substantially in a plane from an innermost coil to an outermost coil.

Growing community of inventors

Halikko, Finland

Juha Ellä

Growing community of inventors

Halikko, Finland

Juha Ell&auml;

Juha Ellä