Spurious-Free S₁ Mode AlN/ScAlN-Based Lamb Wave Resonator With Trapezoidal Electrodes

Adjustable effective electromechanical coupling of Lamb wave resonator using AlN/Sc0.096Al0.904N composite films

“…The high phase velocity is generally favored for high frequency applications. 1,3,10) It is also clear that the phase velocity in ScAlN is smaller than that in AlN. This is because replacing Al atoms with Sc atoms results in larger bond angles and longer bond lengths, softening the elasticity coefficient.…”

“…As l h/ decreases, the S1 mode gradually exhibits a mode similar to the FBAR mode, mainly determined by the maximum piezoelectric constant e 33 in AlN, although it is also related to e . 31 1,10) Therefore, adopting a double-IDT configuration can enhance the electric field distribution in the Z-direction, maximizing the utilization of e 33 and thus allowing the resonator to achieve a higher K . eff 2 10) Figure 1(c) respectively shows the global view and crosssectional view of the double-IDT Lamb wave resonator.…”

“…9) Recently, piezoelectric aluminum nitride Lamb wave resonators (LWRs) have gained popularity due to the fundamental advantages of both SAWs and FBARs, i.e., the ability to have multiple resonating frequencies on a wafer and CMOS process compatibility. 1,3,10) Currently, many studies have demonstrated achievements in the suppression of spurious modes, enhancement of effective electromechanical coupling coefficient (K eff 2 ), energy confinement, and sensor applications of Lamb wave resonators. The rapid development of 5 G communication technology has led to an increasing number of frequency bands.…”

“…Our previous work showed that the composite films based on the combination of AlN and Sc 0.096 Al 0.904 N can effectively improve the K , eff 2 solve the problem of the abnormal particle and reduce the roughness. 6,10) Adjusting the thickness ratio of AlN and ScAlN in the composite film is expected to realize the adjustment of K . eff 2 On the other hand, in the stage of mass production of filters, alloy targets are usually used for physical vapor deposition (PVD), and a fixed-proportion scandium aluminum alloy target is difficult to meet the needs of designers for different K eff 2 of resonators.…”

Development of Temperature Sensor Based on AlN/ScAlN SAW Resonators

“…In our previous work, we sh using the same thickness of AlN and ScAlN can improve crystallinity and crystal o tion of ScAlN films, and compared to pure ScAlN, it has lower dielectric loss [20]. A of AlN/ScAlN composite thin film showed it exhibited higher quality, few defec loss, and was a potential application for acoustic devices [21,22]. AlN/ScAlN-bas vices have a higher Q-factor, which is a benefit for designing environmental sensor high sensitivity.…”