Monolithic Integration of Released and Solidly Mounted RF Acoustic Devices on Heterogeneous Substrate

This work first presents the monolithic integration of the solidly mounted surface acoustic wave (SAW) devices and the released Lamb wave devices on the Y128-cut LiNbO
3
-on-silicon (LNOSi) substrate. The Rayleigh mode SAW resonators showing a phase velocity (v
p
) of about 3700 m/s and effective electromechanical coupling coefficients (k
²
eff
) between 7.3% to 9.5% are suitable for low-frequency and small-band filters, while the first order antisymmetric Lamb wave (A1) resonators showing scalable v
p
from 9476 m/s to 15280 m/s and k
²
eff
between 9.2% to 23.4% are suitable for mid-, high-frequency and large-bandwidth filters. The Al mode and Rayleigh mode filters were also fabricated and measured, exhibiting 3-dB fractional bandwidths (FBW) of 5.5% and 2.4% around 2.1 GHz, respectively. The hybrid acoustic devices with complementary properties on LNOSi substrate show a great potential for applications in the hundred-filter sub-6 GHz RF front-ends.