SAW Resonators Based on High-Crystalline AlScN Film Grown by a Two-Step Method of MOCVD and PVD

In this paper, we employ a novel two-step approach combining metal-organic chemical vapor deposition (MOCVD) and physical vapor deposition (PVD) techniques to grow high-quality AlScN piezoelectric thin film. MOCVD was initially utilized to grow a seed layer of 100 nm high-crystalline AlN on a Si substrate. Magnetron sputtering—a technique known as PVD for its low deposition temperatures, simple process control and low cost—was employed to deposit another thick layer of 500 nm AlScN. This hybrid two-step approach yielded excellent crystal quality. Based on the high-crystalline AlScN thin film, we designed and fabricated SAW resonators to verify the device performance. The SAW resonator with wavelength of 800 nm operates at 5.35 GHz and demonstrates the highest Bode-Q<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">max</inf> of 639. By using the two-step technique, this work demonstrates a feasible way to enable high-frequency, high-Q and especially low-cost AlScN SAW resonators for frequency control applications.