Low cost packaging for thin-film resonators and thin-film resonator-based filters
First Claim
1. A method for making a microelectronic device including an acoustic resonator, said method comprising the steps of:
- providing a substrate;
disposing a piezoelectric resonator on the substrate;
disposing an acoustic reflector over and acoustically coupled to the piezoelectric resonator; and
encapsulating the piezoelectric resonator and acoustic reflector with an encapulsant acoustically coupled to the reflector.
1 Assignment
0 Petitions
Accused Products
Abstract
An acoustic reflector (48) is applied over a thin-film piezoelectric resonator (41, 61) which is supported on a semiconductor or semiconductor-compatible substrate (42, 62) of a microelectronic device (40, 60), enabling an encapsulant (49) to be applied over the reflector-covered resonator without acoustically damping the resonator. In one embodiment, alternating high and low acoustic impedance layers (51, 53 . . . 55) of one-quarter wavelength thicknesses constructively reflect the resonating wavelength to make an encapsulant in the form of an inexpensive plastic molding compound appear as a "clamping" surface to a resonator (41) peripherally supported over an opening (43) on a silicon substrate (42). In another embodiment, an encapsulant- and reflector-covered resonator (61) is mechanically supported above a second reflector (68) which eliminates the need for peripheral support, making substrate (68) also appear as a clamping surface. The invention enables low cost plastic packaging of resonators and associated circuitry on a single monolithic structure. A radio frequency transceiver front-end application is given as an exemplary implementation.
144 Citations
11 Claims
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1. A method for making a microelectronic device including an acoustic resonator, said method comprising the steps of:
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providing a substrate; disposing a piezoelectric resonator on the substrate; disposing an acoustic reflector over and acoustically coupled to the piezoelectric resonator; and encapsulating the piezoelectric resonator and acoustic reflector with an encapulsant acoustically coupled to the reflector. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A method for making a microelectronic device including an acoustic resonator, said method comprising the steps of:
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providing a silicon substrate; depositing a first acoustic reflector on and acoustically coupled to the substrate; depositing a first electrode layer over and acoustically coupled the first acoustic resonator; depositing a piezoelectric material layer over and acoustically coupled to the first electrode layer; depositing a second electrode layer over and acoustically coupled the piezoelectric material layer; depositing a second acoustic reflector over and acoustically coupled to the second electrode layer; and flowing a curable encapsulant over the deposited first and second acoustic reflectors, first and second electrode layers and piezoelectric material layers; and curing the flowed encapsulant in place.
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Specification