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ACOUSTIC BANDGAP STRUCTURES FOR INTEGRATION OF MEMS RESONATORS

  • US 20150237423A1
  • Filed: 01/26/2015
  • Published: 08/20/2015
  • Est. Priority Date: 03/21/2013
  • Status: Active Grant
First Claim
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1. An acoustic bandgap device formed using a semiconductor fabrication tool, the semiconductor fabrication tool having a minimal feature thickness and an allowable via width based on a design rule check of the semiconductor fabrication tool, the device comprising:

  • a substrate lying in an x-y plane defining an x-direction and a y-direction;

    an acoustic resonant cavity disposed over the substrate;

    a phononic crystal disposed over the acoustic resonant cavity, the phononic crystal comprising a plurality of unit cells disposed in a periodic arrangement, each unit cell comprising;

    (i) at least one higher acoustic impedance structure having a longitudinal axis oriented in the y-direction and a thickness in the x-direction greater than or about equal to the minimal feature thickness of the semiconductor fabrication tool, the at least one higher acoustic impedance structure comprising at least one of;

    at least one via structure, each via structure having a width in the x-direction about equal to the allowable via width of the semiconductor fabrication tool; and

    at least one longitudinal bar, each longitudinal bar having a width in the x-direction greater than the width of the at least one via structure; and

    (ii) at least one lower acoustic impedance material bordering at least a portion of the at least one higher acoustic impedance structure and forming at least a portion of a remainder of the respective unit cell;

    wherein a ratio of an acoustic impedance of the higher acoustic impedance structure to an acoustic impedance of the lower acoustic impedance material is greater than 1.0; and

    wherein the phononic crystal suppresses phononic excitations in at least one frequency band, thereby providing at least one phononic bandgap.

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