Method of making an acoustic wave resonator

Details Method of making an acoustic wave resonator Method of making an acoustic wave resonator

Filed on

2005-04-05

Date issued

2005-04-05

Examiner

Tugbang, A. Dexter (Department: 3729)

Patent Class

Metal working

SubClass

Piezoelectric device making

Other Related Categories

C029S594000, C029S831000

Type

Reexamination Certificate

Status

active

Patent number

06874212

Description

ABSTRACT:
A method of fabricating an acoustic resonator includes forming a ferromagnetic compensator, such as one comprised of a nickel-iron alloy, which at least partially offsets temperature-induced effects introduced by an electrode-piezoelectric stack. The compensator has a positive temperature coefficient of frequency, while the stack has a negative temperature coefficient of frequency. By properly selecting the thickness of the compensator, temperature-induced effects on resonance may be neutralized. Alternatively, the thickness can be selected to provide a target positive or negative composite temperature coefficient of frequency. In order to prevent undue electromagnetic losses in the ferromagnetic compensator, a metallic flashing layer may be added to at least partially enclose the compensator.

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patent: 6060818 (2000-05-01), Ruby et al.
patent: 6-164013 (1994-06-01), None
Krishnaswamy et al., “Film Bulk Acoustic Wave Resonator Technology”, Ultrasonics Symposium, 1990, IEEE Proceedings, De 1990, vol. 1, pp. 529-536.*
Ruby et al., “Micromachined Thin Film Bulk Acoustic Resonators”, Frequency Control Symposium, 1994, IEEE 1994 International Proceedings, Jun. 1994, pp. 135-138.*
Endoh, Yasuo et al.,“Zero Sound Anomaly in a Ferroelectric Invar Alloy Fe65Ni35,” Journal of the Physical Society of Japa, vol. 46,No. 3,Mar. 1979, pp 806-814.
Lakin, K.M., “Thin Film Resonators and Filters,” 1999 IEEE Ultrasonics Symposium, 0-7803-5725-6/99, 1999.
Manosa,Li. et al., “Acoustic-mode vibrational anharmonicity related to the anomalous thermal expansion of Invar iron alloys,”The American Physical Society, vol. 45,No. 5, Feb. 1, 1992, pp 2224-2236.

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