Wave transmission lines and networks – Coupling networks – Electromechanical filter
Reexamination Certificate
2000-09-26
2002-11-26
Pascal, Robert J. (Department: 2817)
Wave transmission lines and networks
Coupling networks
Electromechanical filter
C333S189000, C333S191000, C333S192000, C029S025350, C310S322000, C310S324000, C310S335000
Reexamination Certificate
active
06486751
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to thin film resonators (TFR), and more particularly to a thin film bulk acoustic wave (BAW) resonator structure that provides increased bandwidth, and to the method of manufacturing such resonator structures.
Thin film resonators (hereinafter “TFR”) are typically used in high-frequency environments ranging from several hundred megahertz (MHz) to several Gigahertz (GHz). A TFR component typically comprises a piezoelectric material interposed between two conductive electrodes, one of which is formed on a support structure such as a membrane, or on a plurality of alternating reflecting layers formed on a semiconductor substrate which may be made of silicon or quartz, for example, or on another support structure. The piezoelectric material preferably comprises ZnO, CdS, AlN, or combinations thereof. The electrodes are most often formed from a conductive material such as Al, Mo, Pt, Cu, Au, Ti, Cr, and combinations thereof, but may be formed from other conductors as well.
TFR components are often used in filters, more particularly in TFR filter circuits applicable to a myriad of communication technologies. For example, TFR filter circuits may be employed in cellular, wireless and fiber-optic communications, as well as in computer or computer-related information-exchange or information-sharing systems.
The desire to render these increasingly complicated communication systems portable and even hand-held places significant demands on filtering technology, particularly in the context of increasingly crowded radio frequency resources. TFR filters must meet strict performance requirements which include: (a) being extremely robust, (b) being readily mass-produced and (c) being able to sharply increase performance to size ratio achievable in a frequency range extending into the Gigahertz region. Moreover, some of the typical applications noted above for these TFR filters require passband widths up to 4% of the center frequency (for example, for a 2 GHz center frequency, this would be a bandwidth of about 80 MHz). This bandwidth is vital to covering some of the wider bandwidth RF filter applications such as GSM (Global system for mobile communications.)
This bandwidth is not easily achieved using common piezoelectrics such as AIN, especially on solidly mounted resonators on acoustic mirrors which heretofore typically exhibit resonance/anti-resonance separations of 2% or less. Additionally these devices show undesirable lateral non uniform wave oscillation that degrades the device performance due to the large width to thickness ratios of TFR devices.
Some solutions to the inadequate bandwidth problem include the addition of external inductance to the TFR elements when used in filters. However such solution does not address the fundamental limitation in the TFR itself and incorporates at least one additional element in the manufacture of a TFR filter There is, therefore, still a need for a TFR structure for use in the 2 Gigahertz frequency range with an improved bandwidth.
SUMMARY OF THE INVENTION
This invention provides a thin film resonator comprising a plurality of distinct elemental resonators separated by spaces and connected in parallel. Each of the elemental resonators has a length, a width and a height. The elemental resonator height is at least equal to one of the width or length of the elemental resonator.
According to this invention there is also provided a thin film acoustic resonator comprising a support, a first electrode over said support, a piezoelectric layer on said first electrode and a second electrode on said piezoelectric layer wherein said piezoelectric layer comprises a plurality of substantially similar distinct piezoelectric structures adjacent and separated from each other by spaces. Each of said structures has a length, a width and a height, the height being at least equal to either width or length. The electrodes electrically connect the piezoelectric structures in parallel.
Still according to this invention, there is provided an acoustic resonator filter comprising at least one thin film acoustic resonator comprising a plurality of distinct elemental resonators separated by interstitial spaces and connected in parallel each of said elemental resonators having a length, a width and a height, wherein the height is at least equal to one of either the width or length of the elemental resonator.
The above described resonators exhibit improved bandwidths and oscillation uniformity.
Further according to the present invention, is provided a method of manufacturing a thin film resonator, the method comprising forming on a common first electrode a plurality of distinct piezoelectric structures each of said structures comprising a length, a width and a height, wherein the height is formed at least equal to either one of the width or length, and forming a common second electrode on said structures.
REFERENCES:
patent: 4386328 (1983-05-01), Masuda et al.
patent: 4502932 (1985-03-01), Kline et al.
patent: 4556812 (1985-12-01), Kline et al.
patent: 4719383 (1988-01-01), Wang et al.
patent: 4890370 (1990-01-01), Fukuda et al.
patent: 4988957 (1991-01-01), Thompson et al.
patent: 5075641 (1991-12-01), Weber et al.
patent: 5166646 (1992-11-01), Avanic et al.
patent: 5185589 (1993-02-01), Krishnaswamy et al.
patent: 5231327 (1993-07-01), Ketcham
patent: 5232571 (1993-08-01), Braymen
patent: 5233259 (1993-08-01), Krishnaswamy et al.
patent: 5260596 (1993-11-01), Dunn et al.
patent: 5283458 (1994-02-01), Stokes et al.
patent: 5291159 (1994-03-01), Vale
patent: 5294898 (1994-03-01), Dworsky et al.
patent: 5303457 (1994-04-01), Falkner, Jr. et al.
patent: 5334960 (1994-08-01), Penunuri
patent: 5348617 (1994-09-01), Braymen
patent: 5367308 (1994-11-01), Weber
patent: 5373268 (1994-12-01), Dworsky et al.
patent: 5381385 (1995-01-01), Greenstein
patent: 5403701 (1995-04-01), Lum et al.
patent: 5404628 (1995-04-01), Ketcham
patent: 5438554 (1995-08-01), Seyed-Bolorforosh et al.
patent: 5446306 (1995-08-01), Stokes et al.
patent: 5552655 (1996-09-01), Stokes et al.
patent: 5559358 (1996-09-01), Burns et al.
patent: 5587620 (1996-12-01), Ruby et al.
patent: 5596239 (1997-01-01), Dydyk
patent: 5617065 (1997-04-01), Dydyk
patent: 5630949 (1997-05-01), Lakin
patent: 5646583 (1997-07-01), Seabury et al.
patent: 5692279 (1997-12-01), Mang et al.
patent: 5698928 (1997-12-01), Mang et al.
patent: 5702775 (1997-12-01), Anderson et al.
patent: 5714917 (1998-02-01), Ella
patent: 5760663 (1998-06-01), Pradal
patent: 5780713 (1998-07-01), Ruby
patent: 5789845 (1998-08-01), Wadaka et al.
patent: 5815054 (1998-09-01), Vojak et al.
patent: 5821833 (1998-10-01), Lakin
patent: 5847792 (1998-12-01), Kobayashi et al.
patent: 5853601 (1998-12-01), Krishaswamy et al.
patent: 5864261 (1999-01-01), Weber
patent: 5872493 (1999-02-01), Ella
patent: 5873153 (1999-02-01), Ruby et al.
patent: 5873154 (1999-02-01), Ylilammi et al.
patent: 5883575 (1999-03-01), Ruby et al.
patent: 5884378 (1999-03-01), Dydyk
patent: 5894647 (1999-04-01), Lakin
patent: 5910756 (1999-06-01), Ella et al.
patent: 5923390 (1999-07-01), Jung Mok et al.
patent: 5928598 (1999-07-01), Anderson et al.
patent: 5942958 (1999-08-01), Lakin
patent: 5963856 (1999-10-01), Kim
patent: 6051907 (2000-04-01), Ylilammi
patent: 6060818 (2000-05-01), Ruby et al.
patent: 6081171 (2000-06-01), Ella
patent: 6087198 (2000-07-01), Panasik
patent: 6127768 (2000-10-01), Stoner et al.
patent: 6150703 (2000-11-01), Cushman et al.
patent: 6198208 (2001-03-01), Yano et al.
patent: 6204737 (2001-03-01), Ella
patent: 6215375 (2001-04-01), Larson, III et al.
patent: 6252290 (2001-06-01), Quek et al.
R. Ruby et al., “Micromachined Thin Film Bulk Acoustic Resonators”,IEEE 1994 Frequency Control Symposium; Jun., 1994, pp. 135-138.*
H. Morkner et al., “An Integrated FBAR Filter and PHEMT Switched-Amp For Wireless Applications”,1999 IEEE MTT-S Digest; May, 1999, pp. 1393-1395.*
R. Ruby, “Micromachined Cellular Filters”,1996 IEEE MTT-S Digest; Jun., 1996, pp. 1149-1152.
Barber Bradley Paul
Chan Edward
Graebner John Edwin
Agere Systems Inc.
Pascal Robert J.
Ratner & Prestia
Summons Barbara
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