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Encapsulated packaging for thin-film resonators and thin-film resonator-based filters having a piezoelectric resonator between two acoustic reflectors

  • US 6,548,942 B1
  • Filed: 05/15/2000
  • Issued: 04/15/2003
  • Est. Priority Date: 02/28/1997
  • Status: Expired due to Term
First Claim
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1. A microelectronic device, comprising:

  • a substrate, and the substrate comprises silicon;

    a piezoelectric resonator disposed on the substrate, the piezoelectric resonator comprises a first electrode layer of metal deposited on the silicon, a layer of piezoelectric material deposited over the first electrode layer, and a second electrode layer of metal deposited over the piezoelectric material layer;

    an acoustic reflector located over and coupled to the piezoelectric resonator;

    an encapsulant comprising a molding compound having a low acoustic impedance, the encapsulant deposited over and encapsulating the piezoelectric resonator and acoustic reflector, the encapsulant making contact with the acoustic reflector;

    the acoustic reflector transforms the low acoustic impedance of the encapsulant into a high acoustic impedance at the acoustic resonator/acoustic reflector interface; and

    wherein the acoustic reflector comprises alternating acoustic reflecting layers of first and second acoustic impedance materials deposited over the second electrode layer of metal;

    the first acoustic impedance being higher than the second acoustic impedance.

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