Shear bulk acoustic resonator and manufacturing method thereof

Abstract

The invention discloses a shear bulk acoustic wave resonator which comprises a substrate and a piezoelectric substrate, the back of the piezoelectric substrate is attached to the substrate, and a cavity is formed in the side, facing the piezoelectric substrate, of the substrate; a lower interdigital transducer located in the cavity is arranged on the back face of the piezoelectric substrate, an upper interdigital transducer is arranged at the position, symmetrical to the lower interdigital transducer, of the front face of the piezoelectric substrate, and the electrode polarity, corresponding to the position of the upper interdigital transducer, of the lower interdigital transducer is the same as the electrode polarity, corresponding to the position of the upper interdigital transducer. The two sides of the piezoelectric substrate are provided with the interdigital transducers which are opposite in position, and the polarities of the interdigital transducers are the same, so that polarization electric fields generated on the upper surface and the lower surface of the piezoelectric substrate in the thickness direction offset each other, the displacement component in the thickness direction during mass point polarization is reduced, clutters on an admittance curve are reduced, and the impedance of the mass point is improved. And the Q value of the device is also improved.

Description

technical field [0001] The invention belongs to the technical field of resonators, and in particular relates to a shear bulk acoustic wave resonator and a manufacturing method thereof. Background technique [0002] With the increasing popularity of 5G technology, radio frequency communication technology is facing the challenges of higher frequency, larger relative bandwidth and higher power; traditional SAW and TC-SAW are limited by power density and lithography technology development, and it is difficult to apply 3.5 For scenarios above GHz, it is difficult for BAW and FBAR technologies to achieve a relative bandwidth of more than 8%, regardless of whether the piezoelectric layer uses AlN or Sc-doped AlN. [0003] Using XBAR (shear bulk acoustic resonator) technology can effectively solve the above problems, by bonding LiNbO on the substrate 3 Single crystal thin plate, and metal electrodes are prepared on LN to excite shear body waves, which can be regarded as A1 mode Lam...

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Problems solved by technology

[0004] However, for XBAR devices, there are often spurious modes such as S0 and A0 near the A1 mode. The existence of these spurious modes not only leads to a lot of clutter on the admittance characteristic curve of the XBAR resonator, but also the spurious modes will cause energy leakage. The Q of the device will also be significantly affected by the

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