Triquint Semiconductor Corporation

Maxim Integrated Products, Inc.

Rick D Lutz

Edward Martin Godshalk

Ralph N Wall

Uppili Sridhar

Masud Hannan

Guillaume Bouche

Garth G Sundberg

A bulk acoustic wave (BAW) resonator is constructed to reduce phase and amplitude ripples in a frequency response. The BAW resonator is fabricated on a substrate 400 &#x3bc;m thick or less, preferably approximately 325 &#x3bc;m, having a first side and a polished second side with a peak-to-peak roughness of approximately 1000 A. A Bragg mirror having alternate layers of a high acoustic impedance material, such as tungsten, and a low acoustic impedance material is fabricated on the first side of the substrate. A BAW resonator is fabricated on the Bragg mirror. A lossy material, such as epoxy, coats the second side of the substrate opposite the first side. The lossy material has an acoustic impedance in the range of 0.01&#xd7; to 1.0&#xd7; the acoustic impedance of the layers of high acoustic impedance material.

Optimal acoustic impedance materials for polished substrate coating to suppress passband ripple in BAW resonators and filters

Methods of reducing phase and amplitude ripples in a BAW resonator frequency response by providing a substrate, fabricating a Bragg mirror having alternate layers of a high acoustic material and a low acoustic material on a first surface of the substrate, fabricating a BAW on the Bragg mirror, and coating a second side of the substrate opposite the first side with a lossy material having an acoustic impedance in the range of 0.01&#xd7; to 1.0&#xd7; the acoustic impedance of the layers of high impedance material, the second surface of the substrate being a polished surface. Various embodiments are disclosed.

Methods of contacting the top layer in a BAW device by depositing a metal layer over the BAW device, patterning the metal layer so that the metal layer extends over and contacts the top electrode layer of the BAW device only at a plurality of spaced apart locations adjacent the periphery of the active resonator area, and has a common region laterally displaced from the top and bottom electrodes and electrically interconnecting the parts of the metal layer extending over and contacting the top electrode of the BAW device at the plurality of spaced apart locations.

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Portland, OR, United States of America

Rick D Lutz