High Figure-of-Merit Film Bulk Acoustic Wave Resonator Based on Al0.87Sc0.13N Film Prepared Using a Novel Dual-Stage Method

The inferior crystalline quality of AlScN has become the bottleneck that hinders further improvement in the performance of thin film bulk acoustic wave resonators (FBAR). To solve the issue, a strategy was judiciously designed to fabricate the high-quality Al0.87Sc0.13 N film by a dual-stage method, which integrated metal–organic chemical vapor deposition (MOCVD) with physical vapor deposition (PVD) together. It was observed that the crystalline quality and surface roughness of the Al0.87Sc0.13 N film were greatly improved using the dual-stage method, which were attributed to the low screw dislocation density of
${5}.{5}\times {10}\,\,^{\mathbf {{9}}}$
cm
$^{\mathbf {-{2}}}$
in the single crystalline GaN buffer layer prepared by MOCVD. The FBAR based on the above Al0.87Sc0.13 N film exhibited an excellent figure of merit of 236, which was 63% higher than that prepared by single-step method while surpassing most of the previous reports, indicating the superiority of the proposed strategy. Moreover, the proposed strategy has combined the advantages of MOCVD and PVD together while avoiding the shortcomings of large residual stress of MOCVD.