HBAR resonator with a high level of integration

摘要

The invention relates to a resonator of the high bulk acoustic resonator HBAR type, for operating at a pre-determined working frequency, comprising: a piezoelectric transducer (6), an acoustic substrate (10), a counter-electrode (8) formed by a metal layer adhering to a first face of the transducer (6) and a face of the acoustic substrate (10), and an electrode (4) arranged on a second face of the transducer (6) facing away from the first face of the transducer (6) and the substrate (10). Said resonator is characterized in that the relative arrangement of the transducer (6) and the substrate (10) is such that the polarization direction P of the shearing mode of the transducer (6) and the direction of polarization P of the at least one shearing mode of the substrate (10) corresponding to the second cutting angle θ2 are aligned, and the second cutting angle θ2 of the substrate (10) is such that the temperature coefficient of the frequency of the corresponding first order CTFB1 is a local extremum with an absolute value of less than 20 ppm·K−1, and the variation of CTFB1 from said value of Θ2 is slight with an absolute value of less than 2 ppm·K−1/degree.

主权项

1. A resonator of the high bulk acoustic resonator type for operating at a predetermined working frequency, comprising:
a piezoelectric transducer (6) formed by a layer with a first thickness of a first material oriented along an angle φ defined by the nomenclature (YXw)/φ of the IEEE Std-176 (1949 revision) standard equal to zero, cut along a first cutting angle θ1 defined by the nomenclature (YX1)/θ of the IEEE Std-176 (1949 revision) standard, such that the electroacoustic coupling of the shear waves within that material alone is greater than 5%, the transducer (6) having a temperature coefficient of the frequency CTFA as a function of the first cutting angle θ1, an acoustic substrate (10) formed by a second layer with a second thickness of a second material having a working frequency acoustic quality coefficient product at least equal to 5.1012, oriented along an angle φ defined by the nomenclature (YXw)/φ of the IEEE Std-176 (1949 revision) standard equal to zero, cut along a second cutting angle θ2 defined by the nomenclature (YX1)/θ of the IEEE Std-176 (1949 revision) standard, having at least one polarization direction {right arrow over (P)}B1 corresponding to a first shearing mode of vibration, the acoustic substrate (10) having a temperature coefficient of the frequency of the first order CTFB1 corresponding to the at least one shearing mode and depending on the second cutting angle θ2, a counter-electrode (8) formed by a layer of metal adhering to a first face of the transducer (6) and a face of the acoustic substrate (10), and an electrode (4) arranged on a second face of the transducer (6) facing away from the first face of the transducer (6) and the substrate (10), characterized in that the relative arrangement of the transducer (6) and the substrate (10) is such that the direction of polarization {right arrow over (P)}A of the shearing mode of the transducer (6) and the polarization direction {right arrow over (P)}B1 of the at least one shearing mode of the substrate (10) corresponding to the second cutting angle θ2 are aligned, and the second cutting angle θ2 of the substrate (10) is such that the temperature coefficient of the frequency of the corresponding first order CTFB1 is a local extremum with an absolute value of less than 20 ppm·K−1 and the variation of CTFB1 around that value of θ2 is slight with an absolute value of less than 2 ppm·K−1/degree.