Design of Single-Port Surface Acoustic Wave (SAW) Resonator on GaN Wafer as Stress Tester System for Micro and Nano Structures

In pursuit of our proposed approach in an earlier paper on the use of Surface Acoustic Wave (SAW) devices for stress testing of micro/nano-sized functional elements in electronic packaging, this paper presents the design and simulation of a SAW resonator device on a Gallium Nitride (GaN) wafer substarte with aluminum metallization and for a target frequency of about <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$f$</tex><inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</inf>≈ 850 MHz. Utilizing a combination of Finite Element Modeling (FEM) and Coupled Mode (COM) theory, we analyze the behavior of the SAW resonator for reflectivity, and the resonance characteristics of the device. The results indicate a resonance peak but with minimal reflectivity, which can be attributed to the thin and lightweight aluminum metallization. A minimal-sized device model was also analyzed to study the reflectivity behavior and optimize the gap between transducer and reflector grating, revealing periodic variations in SAW wave amplitude. The findings demonstrate the feasibility of using GaN-based SAW devices for stress testing at lower frequencies and suggest improvements in metallization design to enhance device performance.